Avinger (AVGR) 10-K20 Mar 242023 FY Annual reportFinancial data

Company Profile

Document And Entity Information

Document And Entity Information - USD ($) $ in Millions	12 Months Ended
Document And Entity Information - USD ($) $ in Millions	Dec. 31, 2023	Mar. 08, 2024	Jun. 30, 2023
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Document Transition Report	false
Entity File Number	001-36817
Entity Registrant Name	AVINGER, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-8873453
Entity Address, Address Line One	400 Chesapeake Drive
Entity Address, City or Town	Redwood City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94063
City Area Code	650
Local Phone Number	241-7900
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	AVGR
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 6.8
Entity Common Stock, Shares Outstanding (in shares)		1,702,226
Auditor Firm ID	659
Auditor Name	Moss Adams LLP
Auditor Location	San Francisco, California
Entity Central Index Key	0001506928
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 5,275	$ 14,603
Accounts receivable, net of allowance for doubtful accounts of $41 and $73 at December 31, 2023 and 2022, respectively	1,014	1,057
Inventories, net	5,298	4,965
Prepaid expenses and other current assets	575	362
Total current assets	12,162	20,987
Right of use asset	1,102	2,194
Property and equipment, net	487	702
Other assets	19	312
Total assets	13,770	24,195
Current liabilities:
Accounts payable	777	631
Accrued compensation	2,311	1,401
Accrued expenses and other current liabilities	817	657
Leasehold liability, current portion	1,102	1,092
Borrowings	14,293	14,165
Total current liabilities	19,300	17,946
Leasehold liability, long-term portion	0	1,102
Other long-term liabilities	672	1,001
Total liabilities	19,972	20,049
Commitments and Contingencies
Equity, Attributable to Parent [Abstract]
Convertible preferred stock issuable in series, par value of $0.001 Shares authorized: 5,000,000 at December 31, 2023 and 2022 Shares issued and outstanding: 62,881 and 60,961 at December 31, 2023 and 2022, respectively; aggregate liquidation preference related to Series A and Series E convertible preferred stock of $62,796 and $60,876 at December 31, 2023 and 2022, respectively	$ 0	$ 0
Common Stock, Shares Authorized (in shares)	100,000,000	100,000,000
Common stock, par value of $0.001 Shares authorized: 100,000,000 at December 31, 2023 and 2022 Shares issued and outstanding: 1,279,928 and 522,177 at December 31, 2023 and 2022, respectively	$ 1	$ 8
Additional paid-in capital	414,493	406,514
Accumulated deficit	(420,696)	(402,376)
Total stockholders’ (deficit) equity	(6,202)	4,146
Total liabilities and stockholders’ (deficit) equity	$ 13,770	$ 24,195

Balance Sheets (Parentheticals)

Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accounts Receivable, Allowance for Credit Loss, Current	$ 41	$ 73
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.001	$ 0.001
Preferred Stock, Shares Authorized (in shares)	5,000,000	5,000,000
Preferred Stock, Shares Issued (in shares)	62,881	60,961
Preferred Stock, Shares Outstanding, Ending Balance (in shares)	62,881	60,961
Preferred Stock, Liquidation Preference, Value	$ 62,796	$ 60,876
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.001	$ 0.001
Common Stock, Shares Authorized (in shares)	100,000,000	100,000,000
Common Stock, Shares, Issued (in shares)	1,279,928	522,177
Common Stock, Shares, Outstanding, Ending Balance (in shares)	1,279,928	522,177

Statements of Operations and Co

Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Revenues	$ 7,652	$ 8,273
Cost of revenues	5,649	5,619
Gross profit	2,003	2,654
Operating expenses:
Research and development	4,540	4,390
Selling, general and administrative	14,098	14,221
Total operating expenses	18,638	18,611
Loss from operations	(16,635)	(15,957)
Interest expense, net	(1,719)	(1,665)
Other income (expense), net	34	(1)
Net loss and comprehensive loss	(18,320)	(17,623)
Accretion of preferred stock dividends	0	(4,510)
Deemed dividend arising from beneficial conversion feature of convertible preferred stock	0	(5,111)
Net loss applicable to common stockholders	$ (18,320)	$ (27,244)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (23.31)	$ (65.33)
Weighted average common shares used to compute net loss per share, basic and diluted (in shares)	786	417

Statements of Stockholders' (De

Statements of Stockholders' (Deficit) Equity - USD ($) $ in Thousands	Preferred Stock [Member] Series D Preferred Stock [Member]	Preferred Stock [Member]	Common Stock [Member] Series D Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member] Series D Preferred Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member] Series D Preferred Stock [Member]	Retained Earnings [Member]	Series D Preferred Stock [Member]	Total
Balance (in shares) at Dec. 31, 2021		56,451		318,551
Balance at Dec. 31, 2021		$ 0		$ 5		$ 394,471		$ (384,753)		$ 9,723
Issuance of common stock in public offerings, net of commissions and issuance costs (in shares)	7,600	0	0	85,707
Issuance of common stock in public offerings, net of commissions and issuance costs	$ 0	$ 0	$ 0	$ 1	$ 6,721	5,195	$ 0	0	$ 6,721	5,196
Conversion of Series D preferred stock into common stock (in shares)		(7,600)		63,333
Conversion of Series D preferred stock into common stock		$ 0		$ 1		0		0		1
Exercise of pre-funded warrants for common stock (in shares)		0		52,268
Exercise of pre-funded warrants for common stock		$ 0		$ 1		0		0		1
Reclassifications and adjustments due to rounding impact from reverse stock split for fractional shares (in shares)		0		1,745
Reclassifications and adjustments due to rounding impact from reverse stock split for fractional shares		$ 0		$ 0		0		0		0
Issuance of common stock upon vesting of restricted stock units (in shares)		0		573
Issuance of common stock upon vesting of restricted stock units		$ 0		$ 0		0		0		0
Employee stock-based compensation		$ 0		$ 0		127		0		127
Issuance of Series A preferred stock to pay dividends (in shares)		4,510		0
Issuance of Series A preferred stock to pay dividends		$ 0		$ 0		4,510		0		4,510
Accretion of Series A preferred stock dividends		0		0		(4,510)		0		(4,510)
Net and comprehensive loss		$ 0		$ 0		0		(17,623)		(17,623)
Balance (in shares) at Dec. 31, 2022		60,961		522,177
Balance at Dec. 31, 2022		$ 0		$ 8		406,514		(402,376)		4,146
Issuance of common stock in public offerings, net of commissions and issuance costs (in shares)		0		607,236
Issuance of common stock in public offerings, net of commissions and issuance costs		$ 0		$ 1		5,112		0		5,113
Conversion of Series D preferred stock into common stock (in shares)		1,920		0
Conversion of Series D preferred stock into common stock		$ 0		$ 0		1,920		0		1,920
Exercise of pre-funded warrants for common stock (in shares)		0		91,325
Exercise of pre-funded warrants for common stock		$ 0		$ 1		(2)		0		(1)
Reclassifications and adjustments due to rounding impact from reverse stock split for fractional shares (in shares)		0		56,896
Reclassifications and adjustments due to rounding impact from reverse stock split for fractional shares		$ 0		$ (9)		9		0		0
Issuance of common stock upon vesting of restricted stock units (in shares)		0		2,294
Issuance of common stock upon vesting of restricted stock units		$ 0		$ 0		0		0		0
Employee stock-based compensation		0		0		940		0		940
Net and comprehensive loss		$ 0		$ 0		0		(18,320)		(18,320)
Balance (in shares) at Dec. 31, 2023		62,881		1,279,928
Balance at Dec. 31, 2023		$ 0		$ 1		$ 414,493		$ (420,696)		$ (6,202)

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities
Net loss	$ (18,320)	$ (17,623)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	289	196
Amortization of debt issuance costs and debt discount	83	83
Stock-based compensation	940	127
Noncash interest expense and other charges	1,964	1,795
Change in right of use asset	53	93
Provision for excess and obsolete inventories	404	272
Other non-cash charges	(32)	69
Changes in operating assets and liabilities:
Accounts receivable	75	269
Inventories	(802)	(1,387)
Prepaid expenses and other current assets	(213)	(62)
Other assets	240	15
Accounts payable	146	(764)
Accrued compensation	42	(208)
Accrued expenses and other current liabilities	160	(61)
Other long-term liabilities	539	426
Net cash used in operating activities	(14,432)	(16,760)
Cash flows from investing activities
Purchase of property and equipment	(8)	(51)
Net cash used in investing activities	(8)	(51)
Cash flows from financing activities
Net cash provided by financing activities	5,112	11,917
Net change in cash and cash equivalents	(9,328)	(4,894)
Cash and cash equivalents, beginning of period	14,603	19,497
Cash and cash equivalents, end of period	5,275	14,603
Supplemental disclosure of cash flow information
Accretion of Series A preferred stock dividends	0	4,510
Issuance of Series A preferred stock as dividend payment	0	4,510
Transfers between inventory and property and equipment	66	751
Conversion of Loan Principal and Accrued Interest Into Series E Convertible Preferred Stock [Member]
Supplemental disclosure of cash flow information
Conversion of CRG loan principal and accrued interest into Series E convertible preferred stock	1,920	0
Common Stock [Member]
Cash flows from financing activities
Proceeds from the issuance of convertible preferred stock, net of commissions and issuance costs	0	6,721
Preferred Stock [Member]
Cash flows from financing activities
Proceeds from the issuance of convertible preferred stock, net of commissions and issuance costs	$ 5,112	$ 5,196

Insider Trading Arrangements

Insider Trading Arrangements	12 Months Ended
Insider Trading Arrangements	Dec. 31, 2023
Insider Trading Arr Line Items
Material Terms of Trading Arrangement [Text Block]	ITEM 9B. OTHER INFORMATION None
Rule 10b5-1 Arrangement Adopted [Flag]	false
Non-Rule 10b5-1 Arrangement Adopted [Flag]	false
Rule 10b5-1 Arrangement Terminated [Flag]	false
Non-Rule 10b5-1 Arrangement Terminated [Flag]	false

Note 1 - Organization

Note 1 - Organization	12 Months Ended
Note 1 - Organization	Dec. 31, 2023
Notes to Financial Statements
Nature of Operations [Text Block]	1. Organization Organization, Nature of Business Avinger, Inc. (the “Company”), a Delaware corporation, was incorporated in March 2007. The Company designs, manufactures and sells image-guided, catheter-based systems that are used by physicians to treat patients with peripheral artery disease (“PAD”). Patients with PAD have a build-up of plaque in the arteries that supply blood to areas away from the heart, particularly the pelvis and legs. The Company manufactures and sells a suite of products in the United States (“U.S.”) and in select international markets. The Company has developed its Lumivascular platform, which integrates optical coherence tomography (“OCT”) visualization with interventional catheters and is the industry’s only system that provides real-time intravascular imaging during the treatment portion of PAD procedures. The Company’s Lumivascular platform consists of a capital component, Lightbox consoles, as well as a variety of disposable catheter products. The Company’s current catheter products include Ocelot, Tigereye and Tigereye ST, which are designed to allow physicians to penetrate a total blockage in an artery, known as a chronic total occlusion (“CTO”). The Company also has image-guided atherectomy products, Pantheris, Pantheris SV and Pantheris LV, which are designed to allow physicians to precisely remove arterial plaque in PAD patients. The Company is in the process of developing next-generation CTO crossing devices to target coronary CTO markets. The Company is located in Redwood City, California. Liquidity Matters The accompanying financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) No. 2014-15, Presentation of Financial Statements - Going Concern (Subtopic 205-40) In the course of its activities, the Company has incurred losses and negative cash flows from operations since its inception. On March 5, 2024, the Company entered into a financing as part of a broader strategic collaboration with Zylox-Tonbridge Medical Technology Co., Ltd. (“Zylox-Tonbridge”) in which the Company received an aggregate of $7.5 million before any commissions, legal and accounting fees, and other ancillary expenses as described more fully within Note 14, Subsequent Events. As of December 31, 2023, the Company had an accumulated deficit of $420.7 million. The Company expects to incur losses for the foreseeable future. The Company believes that its cash and cash equivalents of $5.3 million at December 31, 2023 together with the aforementioned March 2024 financing, together with debt and other financing activities and expected revenues from operations will be sufficient to allow the Company to fund its current operations through the second quarter of 2024. The Company received net proceeds of approximately $4.4 million from the sale of its common stock in August 2022, $6.5 million from the sale of its common stock under an At The Market Offering Agreement from the time of activation through the year ended December 31, 2023 and $6.7 million from the sale of Series D preferred stock in January 2022. The Company may seek to raise additional funds in future equity offerings to meet its operational needs and capital requirements for product development, clinical trials and commercialization or other strategic objectives. The Company can provide no assurance that it will be successful in raising funds pursuant to additional equity or debt financings or that such funds will be raised at prices that do not create substantial dilution for its existing stockholders. Given the volatility in the Company’s stock price, any financing that the Company may undertake in the next twelve months could cause substantial dilution to its existing stockholders, and there can be no assurance that the Company will be successful in acquiring additional funding at levels sufficient to fund its various endeavors. These conditions raise substantial doubt about the Company’s ability to continue as a going concern. In addition, the macroeconomic environment has in the past resulted in and could continue to result in reduced consumer and investor confidence, instability in the credit and financial markets, volatile corporate profits and reduced business and consumer spending, which could increase the cost of capital and/or limit the availability of capital to the Company. If the Company is unable to raise additional capital in sufficient amounts or on terms acceptable to it, the Company may have to significantly reduce its operations or delay, scale back or discontinue the development and sale of one or more of its products. The financial statements do not include any adjustments that might result from the outcome of this uncertainty. The Company’s ultimate success will largely depend on its continued development of innovative medical technologies, its ability to successfully commercialize its products and its ability to raise significant additional funding. Additionally, due to the substantial doubt about the Company’s ability to continue operating as a going concern and the “Material Adverse Change” clause in the Loan Agreement with CRG Partners III L.P. and certain of its affiliated funds (collectively “CRG”), the entire amount of outstanding borrowings at December 31, 2023 and 2022 has been classified as current in these financial statements. CRG has not purported that an Event of Default (as defined in the Loan Agreement) has occurred due to a Material Adverse Change. Currently substantially all of our cash and cash equivalents are held at a single financial institution, First Citizens Bank, which acquired our prior banking partner, Silicon Valley Bank in March 2023. On March 10, 2023, the Federal Deposit Insurance Corporation announced that Silicon Valley Bank had been closed by the California Department of Financial Protection and Innovation. While we have regained access to our accounts at Silicon Valley Bank and are evaluating our banking relationships, future disruptions of financial institutions where we bank or have credit arrangements, or disruptions of the financial services industry in general, could adversely affect our ability to access our cash and cash equivalents. If we are unable to access our cash and cash equivalents as needed, our financial position and ability to operate our business will be adversely affected. Equity Offerings January 2022 Offering On January 14, 2022, the Company entered into a securities purchase agreement with several institutional investors pursuant to which the Company agreed to sell and issue, in a registered direct offering (“January 2022 Offering”), an aggregate of 7,600 shares of the Company’s Series D Convertible Preferred Stock, par value of $0.001 per share, at an offering price of $1,000 per share which was convertible into common stock at a conversion price of $120.00 per share. Concurrently, the Company agreed to issue to these investors warrants to purchase up to an aggregate of 53,833 shares of the Company’s common stock (the “Common Warrants”). As a result, the Company received aggregate net proceeds of approximately $6.7 million after underwriting discounts, commissions, legal and accounting fees, and other ancillary expenses. The 53,833 Common Warrants have an exercise price of $144.00 per share and became exercisable beginning July 14, 2022. The Common Warrants will expire five August 2022 Offering On August 4, 2022, the Company entered into a securities purchase agreement with a single institutional investor for the issuance and sale of 98,935 shares of its common stock in a registered direct offering (“RD” or “Registered Direct”) at a purchase price of $26.28 per share, or pre-funded warrants in lieu thereof. In a concurrent private placement, the Company also agreed to issue and sell to the investor 91,324 shares of common stock at the same purchase price as in the registered direct offering, or pre-funded warrants in lieu thereof (“Private Placement” and together with the Registered Direct offering the “August 2022 Offering”). As a result, the Company received aggregate net proceeds of approximately $4.4 million after underwriting discounts, commissions, legal and accounting fees, and other ancillary expenses. As a result, in the Registered Direct offering, the Company issued (i) 46,667 shares of common stock, (ii) and pre-funded warrants in lieu of common stock to purchase up to an aggregate of 52,268 shares of common stock (the “RD Pre-Funded Warrants”) and in the Private Placement, the Company issued pre-funded warrants to purchase up to an aggregate of 91,324 shares of common stock (the “Private Placement Pre-Funded Warrants” and together with the RD Pre-Funded Warrants the “August 2022 Pre-Funded Warrants”). As of December 31, 2023, all the Private Placement Pre-Funded Warrants were exercised leaving none outstanding. In addition, the Company issued to the investor in the August 2022 Offering Series A preferred investment options to purchase up to 190,259 additional shares of the Company’s common stock and Series B preferred investment options to purchase up to 190,259 additional shares of the Company’s common stock (the “Preferred Investment Options”). The Series A preferred investment options have an exercise price of $22.53 per share, are immediately exercisable, and will expire five two At The Market Offering Agreement On May 20, 2022, the Company entered into an At The Market Offering Agreement (the “ATM Agreement”) with H.C. Wainwright & Co., LLC (the “Agent”), as sales agent, pursuant to which the Company may offer and sell shares of common stock, par value $0.001 per share (the “Shares”) up to an aggregate offering price of $7,000,000 from time to time, in an at the market public offering. Sales of the Shares are to be made at prevailing market prices at the time of sale, or as otherwise agreed with the Agent. The Agent will receive a commission from the Company of 3.0% of the gross proceeds of any Shares sold under the ATM Agreement. The Shares sold under the ATM Agreement are offered and sold pursuant to the Company’s shelf registration statement on Form S-3, which was initially filed with the Securities and Exchange Commission (the “SEC”) on March 29, 2022 and declared effective on April 7, 2022, and a prospectus supplement and the accompanying prospectus relating to the At The Market Offering filed with the SEC on May 20, 2022. During the year ended December 31, 2022, the Company sold 39,048 shares of common stock pursuant to the ATM Agreement at an average price of $25.08 per share for aggregate proceeds of $1.0 million, of which approximately $29,000 was paid in the form of commissions to the Agent. On August 3, 2022, the Company suspended sales under the ATM Agreement. On March 17, 2023, the Company reactivated the ATM Agreement. During the year ended December 31, 2023, the Company sold 607,241 shares of common stock at an average price of $9.01 per share for aggregate proceeds of approximately $5.5 million, of which approximately $164,000 was paid in the form of commissions to the Agent. While the Company may attempt additional sales in the future, there can be no assurance that the Company will be successful in acquiring additional funding through these means. Other than the ATM Agreement, the Company currently does not have any commitments to obtain additional funds.

Note 2 - Summary of Significant

Note 2 - Summary of Significant Accounting Policies	12 Months Ended
Note 2 - Summary of Significant Accounting Policies	Dec. 31, 2023
Notes to Financial Statements
Basis of Presentation and Significant Accounting Policies [Text Block]	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). On March 11, 2022, the Company’s Board of Directors approved an amendment to the Company’s amended and restated certificate of incorporation to effect a 1-for-20 reverse stock split of the Company’s issued and outstanding common stock. The reverse stock split became effective on March 14, 2022. On September 8, 2023, the Company’s Board of Directors approved an amendment to the Company’s amended and restated certificate of incorporation to effect a 1-for-15 reverse stock split of the Company’s issued and outstanding common stock. The reverse stock split became effective on September 12, 2023. The par value of the common stock and preferred stock was not adjusted as a result of the reverse stock splits. All common stock, stock options, restricted stock units, restricted stock awards and per share amounts in the financial statements have been retroactively adjusted for all periods presented to give effect to the reverse stock splits. Additionally, the common stock at par and related additional paid-in capital amounts as of December 31, 2022 in the balance sheet, the common stock at par and related additional paid-in capital amounts in the Statement of Stockholders’ Equity as of December 31, 2022 and 2021, and for the year ended December 31, 2022 have also been retroactively reclassified to give effect to the reverse stock splits. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. Management uses significant judgment when making estimates related to its stock-based compensation, accruals related to compensation, the valuation of the common stock warrants, provisions for doubtful accounts receivable and excess and obsolete inventories, clinical trial accruals, and its reserves for sales returns and warranty costs. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions. Fair Value of Financial Instruments The Company has evaluated the estimated fair value of its financial instruments as of December 31, 2023 and 2022. Financial instruments consist of cash and cash equivalents, accounts receivable and payable, and other current liabilities and borrowings. The carrying amounts of cash and cash equivalents, accounts receivable and payable, and other current liabilities approximate their respective fair values because of the short-term nature of those instruments. Based upon the borrowing terms and conditions currently available to the Company, the carrying values of the borrowings approximate their fair value. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at the time of purchase to be cash equivalents. Cash equivalents are considered available-for-sale marketable securities and are recorded at fair value, based on quoted market prices. As of December 31, 2023 and 2022, the Company’s cash equivalents are entirely comprised of investments in money market funds. Any related unrealized gains and losses are recorded in other comprehensive income (loss) and included as a separate component of stockholders’ equity. There were no Concentration of Credit Risk, and Other Risks and Uncertainties Financial instruments that potentially subject the Company to credit risk consist of cash and cash equivalents and accounts receivable to the extent of the amounts recorded on the balance sheets. The Company’s policy is to invest in cash and cash equivalents, consisting of money market funds. These financial instruments are held in Company accounts at one financial institution, First Citizens Bank, which acquired our prior banking partner, Silicon Valley Bank, in March 2023. The counterparties to the agreements relating to the Company’s investments consist of financial institutions of high credit standing. The Company provides for uncollectible amounts when specific credit problems arise. Management’s estimates for uncollectible amounts have been adequate, and management believes that all significant credit risks have been identified at December 31, 2023 and 2022. On March 10, 2023, the Federal Deposit Insurance Corporation announced that Silicon Valley Bank had been closed by the California Department of Financial Protection and Innovation. While we have regained access to our accounts at First Citizens Bank, formerly Silicon Valley Bank and are evaluating our banking relationships, future disruptions of financial institutions where we bank or have credit arrangements, or disruptions of the financial services industry in general, could adversely affect our ability to access our cash and cash equivalents. If we are unable to access our cash and cash equivalents as needed, our financial position and ability to operate our business will be adversely affected. The Company’s accounts receivable are due from a variety of healthcare organizations in the United States and select international markets. The Company provides for uncollectible amounts when specific credit problems arise. Management’s estimates for uncollectible amounts have been adequate, and management believes that all significant credit risks have been identified at December 31, 2023 and 2022. At December 31, 2023, there was one no one The Company manufactures its commercial products in-house, including the Pantheris and Ocelot family of catheters. Certain of the Company’s product components and sub-assemblies are manufactured by sole suppliers, including internally. Disruption in component or sub-assembly supply from these manufacturers or from in-house production would have a negative impact on the Company’s financial position and results of operations. The Company is subject to certain risks, including that its devices may not be approved or cleared for marketing by governmental authorities or be successfully marketed. There can be no assurance that the Company’s products will achieve widespread adoption in the marketplace, nor can there be any assurance that existing devices or any future devices can be developed or manufactured at an acceptable cost and with appropriate performance characteristics. The Company is also subject to risks common to companies in the medical device industry, including, but not limited to, new technological innovations, dependence upon third-party payors to provide adequate coverage and reimbursement, dependence on key personnel and suppliers, protection of proprietary technology, product liability claims, and compliance with government regulations. Existing or future devices developed by the Company may require approvals or clearances from the FDA or international regulatory agencies. In addition, in order to continue the Company’s operations, compliance with various federal and state laws is required. If the Company were denied or delayed in receiving such approvals or clearances, it may be necessary to adjust operations to align with the Company’s currently approved portfolio. If clearance for the products in the current portfolio were withdrawn by the FDA, this may have a material adverse impact on the Company. Disruption of our supply chain capabilities due to trade restrictions, political instability, severe weather, natural disasters, public health crises, terrorism, product recalls, labor supply or stoppages, the financial or operational instability of key suppliers and carriers, government restrictions or measures, or other reasons could impair our ability to distribute our products. The Company believes capacity issues and resource constraints and the related increased cost pressures and burdens on the hospital systems have had and may continue to have an adverse effect on its ability to generate sales due to the fluctuating and unpredictable levels of capacity medical providers have to perform procedures that require the use of its products. In addition, the Company has experienced disruptions in its manufacturing and supply chain, as well as delays in site initiation and patient enrollment for its clinical studies. If the Company is unable to successfully complete these or other clinical studies, its business and results of operations could be harmed. The Company is closely monitoring general economic conditions on global supply chain, manufacturing, and logistics operations. As inflationary pressures increase, the Company has experienced and further anticipates that its production and operating costs may continue to increase, including costs and availability of materials and labor. While the Company has sufficient inventory on-hand to meet its current production requirements and customer demand, it has experienced some constraints with respect to the availability of certain materials and extended lead times from certain key suppliers. The Company has also experienced some delays in shipping products to its customers. Any significant delay or interruption in our supply chain could impair the Company’s ability to meet the demands of its customers in the future and could harm its business. We use technology in substantially all aspects of our business operations, and our ability to serve customers most effectively depends on the reliability of our technology systems. Cybersecurity incidents can include computer viruses, computer denial-of-service attacks, worms, and other malicious software programs or other attacks, covert introduction of malware to computers and networks, impersonation of authorized users, and efforts to discover and exploit any design flaws, bugs, security vulnerabilities or security weaknesses, as well as intentional or unintentional acts by employees or other insiders with access privileges, intentional acts of vandalism by third parties and sabotage. In addition, our technology infrastructure and systems are vulnerable to damage or interruption from natural disasters, power loss and telecommunications failures. Any such disruption to our systems, or the technology systems of third parties on which we rely, the failure of these systems to otherwise perform as anticipated, or the theft, destruction, loss, misappropriation, or release of sensitive and/or confidential information or intellectual property, could require us to notify affected individuals, federal or state agencies or media outlets of the incident and could result in business disruption, negative publicity, loss of customers, potential liability, including litigation or other legal actions against us or the imposition of penalties, fines, fees or liabilities, which may not be covered by our insurance policies, and competitive disadvantage, any or all of which would potentially adversely affect our customer service, decrease the volume of our business and result in increased costs and lower profits. Moreover, a cybersecurity breach could require us to devote significant management resources to address the problems associated with the breach and to expend significant additional resources to upgrade further the security measures we employ to protect information against cyber-attacks and other wrongful attempts to access such information, which could result in a disruption of our operations. While we have invested, and continue to invest, in technology security initiatives and other measures to prevent security breaches and cyber incidents, as well as disaster recovery plans, these initiatives and measures may not be entirely effective to insulate us from technology disruption that could result in adverse effects on our results of operations. Accounts Receivable Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The allowance for doubtful accounts is the Company’s best estimate of the amount of probable credit losses in the Company’s existing accounts receivable. The Company determines the allowance for doubtful accounts based upon an aging of accounts receivable, historical experience, and management judgment. Accounts receivable balances are reviewed individually for collectability. To date, the Company has not experienced significant credit-related losses. Accounts receivable allowance for doubtful accounts provision and recoveries or write-offs are summarized as follows (in thousands): 2023 2022 Beginning balance $ 73 $ 6 Provision 17 70 Recoveries/write-offs (49 ) (3 ) Ending balance $ 41 $ 73 Inventories Inventories are valued at the lower of cost or net realizable value. Cost is determined using the first-in, first-out method for all inventories. The Company’s policy is to write down inventory that has expired or become obsolete, inventory that has a cost basis in excess of its expected net realizable value, and inventory in excess of expected requirements. At each balance sheet date, management evaluates inventories for excess quantities, and obsolescence. This evaluation by management includes analysis of historical sales levels by product, projections of future demand, the risk of technological or competitive obsolescence for products, general market conditions, as well as the feasibility of reworking or using excess or obsolete products or components in the production or assembly of other products that are not obsolete or for which there are not excess quantities in inventory. To the extent that management determines there are excess or obsolete inventory, management adjusts the carrying value to estimated net realizable value. When quantities on hand exceed sales forecasts, a write-down is recorded for such excess inventories along with a corresponding charge to cost of revenues. The estimate of excess quantities is subjective and primarily dependent on the estimates of future demand for a particular product. Specifically, the future demand is derived based on our historical experience, from discussion with users of our products and general market conditions. Changes in assumptions of product demand could have a significant impact on the amount of write-down recorded. Inventory used in clinical trials is expensed at the time of production and recorded as research and development expense if the inventory is contractually being provided at no cost to the clinical site. The cost of inventories are regularly reviewed against estimated market value and record a lower of cost or market reserve for inventories that have a cost in excess of estimated market value, which could have a material impact on the gross margin and inventory balances based on additional write-downs to net realizable value or a benefit from inventories previously written down. Property and Equipment Property and equipment are recorded at cost. Repairs and maintenance costs are expensed as incurred. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the assets of generally three five Impairment of Long-Lived Assets The Company reviews long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. If indicators of impairment exist, an impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. Impairment, if any, is measured as the amount by which the carrying amount of the long-lived asset exceeds its fair value. The Company has not recorded any impairment of long-lived assets since inception through December 31, 2023. Revenue Recognition The Company’s revenues are derived from (1) sale of Lightbox consoles, (2) sale of disposables, which consist of catheters and accessories, and (3) sale of customer service contracts and maintenance. The Company sells its products directly to hospitals and medical centers as well as through distributors. The Company accounts for a contract with a customer when there is a legally enforceable contract between the Company and the customer, the rights of the parties are identified, the contract has commercial substance, and collectability of the contract consideration is probable. The Company’s revenues are measured based on consideration specified in the contract with each customer, net of any sales incentives and taxes collected from customers that are remitted to government authorities. For all sales, the Company uses either a signed agreement, a binding purchase order or other written documentation as evidence of an arrangement. The Company’s revenue recognition policies generally result in revenue recognition at the following points: 1. Lightbox console sales: Provided all other criteria for revenue recognition have been met, the Company recognizes revenue for Lightbox console sales directly to end customers when delivery and acceptance occurs, which is defined as receipt by the Company of an executed form that the installation process is complete. If installation is not required, as is the case with the Lightbox 3, recognition occurs upon the completion of delivery pursuant to the stated delivery terms. 2. Sales of disposables: Disposable revenues consist of sales of the Company’s catheters and accessories and are recognized when the product has shipped, risk of loss and title has passed to the customer and collectability is reasonably assured. 3. Service revenue: Service contract revenue consists of preventative maintenance, upgrades, and service contracts. Service contracts are recognized ratably over the term of the service period and maintenance contract revenue is recognized when work is completed. To date, service revenue has been insignificant. The Company offers its customers the ability to purchase or lease the Lightbox console. In addition, the Company provides a Lightbox under a limited commercial evaluation program to allow accounts to install and utilize the Lightbox for a limited trial period. When a Lightbox is placed under a lease agreement or under a commercial evaluation program, the Company retains title to the equipment and it remains capitalized on its balance sheet under property and equipment. Depreciation expense on these placed Lightboxes is recorded to cost of revenues on a straight-line basis. The costs to maintain these placed Lightboxes are charged to cost of revenues as incurred. The Company evaluates its lease and commercial evaluation program agreements and accounts for these contracts under the guidance in Accounting Standards Codification (“ASC”) 842, Leases Revenue from Contracts with Customers (Topic 606) The Company assessed whether the embedded lease is an operating lease or sales-type lease. Based on the Company’s assessment of the guidance and given that any payments under the lease agreements are dependent upon contingent future sales, it was determined that collectability of the minimum lease payments is not reasonably predictable. Accordingly, the Company concluded the embedded lease did not meet the criteria of a sales-type lease and accounts for it as an operating lease. The Company recognizes revenue allocated to the lease as the contingent disposable product purchases are delivered and are included in revenues within the statement of operations and comprehensive loss. For sales of disposables through distributors, the Company recognizes revenue when control of the product transfers from the Company to the distributor. The distributors are responsible for all statutory obligations, marketing, sales, training and warranty in their respective territories. The standard terms and conditions contained in the Company’s distribution agreements do not provide price protection or stock rotation rights to any of its distributors. In addition, its distributor agreements do not allow the distributor to return or exchange products, and the distributor is obligated to pay the Company upon invoice regardless of its ability to resell the product. Cost of Revenues Cost of revenues consists primarily of manufacturing overhead costs, material costs and direct labor. A significant portion of the Company’s cost of revenues currently consists of manufacturing overhead costs. These overhead costs include the cost of quality assurance, material procurement, inventory control, facilities, equipment and operations supervision and management. Cost of revenues also includes depreciation expense for the Lightboxes under lease, deployed with sales personnel and evaluation agreements, product warranty costs, product written-off due to excess or obsolescence, and certain direct costs such as shipping costs. Product Warranty Costs The Company typically offers a one 2023 2022 Beginning balance $ 109 $ 187 Warranty provision 107 22 Usage/Release (23 ) (100 ) Ending balance $ 193 $ 109 Research and Development The Company expenses research and development costs as incurred. Research and development expenses include personnel and personnel-related costs, costs associated with pre-clinical and clinical development activities, and costs for prototype products that are manufactured prior to market approval for that prototype product, and internal and external costs associated with the Company’s regulatory compliance, including the costs of outside consultants and contractors that assist in the process of submitting and maintaining regulatory filings, and overhead costs, including allocated facility and related expenses. Clinical Trials The Company accrues and expenses costs for its clinical trial activities performed by third parties, including clinical research organizations and other service providers, based upon estimates of the work completed over the life of the individual study in accordance with associated agreements. The Company determines these estimates through discussion with internal personnel and outside service providers as to progress or stage of completion of trials or services pursuant to contracts with clinical research organizations and other service providers and the agreed-upon fee to be paid for such services. Stock-Based Compensation Stock-based compensation for the Company includes amortization related to all stock options, restricted stock units (“RSU”), and restricted stock awards (“RSA”) based on the grant-date estimated fair value. The fair value of stock options is estimated on the date of grant using the Black-Scholes option pricing model and recognized as expense on a straight-line basis over the vesting period of the award. The Company has not granted any stock options since 2017. The Company measures the fair value of RSUs and RSAs using the closing stock price of a share of the Company’s common stock on the grant date and is recognized as expense on a straight-line basis over the vesting period of the award. As allowed under ASU No. 2016‑09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting Foreign Currency The Company records net gains and losses resulting from foreign exchange transactions as a component of foreign currency exchange losses in other income (expense), net. During the years ended December 31, 2023 and 2022, the Company recorded a net gain of $12,000 and a net loss of $12,000 of foreign currency exchange, respectively. Income Taxes The Company utilizes the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and tax reporting bases of assets and liabilities and are measured using enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company’s policy is to record interest and penalties on uncertain tax positions as income tax expense when they occur. During the years ended December 31, 2023 and 2022, the Company did not Net Loss per Share Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is computed by dividing the net loss applicable to common stockholders by the weighted average number of shares of common stock outstanding during the period, without consideration for potential dilutive common shares. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss applicable to common stockholders by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Any common stock shares subject to repurchase are excluded from the calculations as the continued vesting of such shares is contingent upon the holders’ continued service to the Company. As of December 31, 2023 and 2022, there were no Net loss per share applicable to common stockholders was determined as follows (in thousands, except per share data): Year Ended December 31, 2023 2022 Net loss applicable to common stockholders $ (18,320 ) $ (27,244 ) Weighted average common stock outstanding, basic and diluted 786 417 Net loss per share attributable to common stockholders, basic and diluted $ (23.31 ) $ (65.33 ) The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted average shares outstanding because such securities have an anti-dilutive impact due to losses reported: Year Ended December 31, 2023 2022 Common stock warrants equivalents 477,182 267,314 Common stock options 15 15 Convertible preferred stock 61,745 58,080 Unvested restricted stock units 123,547 365 662,489 325,774 Comprehensive Loss For the years ended December 31, 2023 and 2022, there was no difference between comprehensive loss and the Company’s net loss. Segment and Geographical Information The Company operates and manages its business as one Recent Accounting Pronouncements Recent accounting standards not yet adopted In December 2023, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures In August 2020, the FASB issued ASU No. 2020-06, Debt Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging Contracts in Entity s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity s Own Equity

Note 3 - Fair Value Measurement

Note 3 - Fair Value Measurements	12 Months Ended
Note 3 - Fair Value Measurements	Dec. 31, 2023
Notes to Financial Statements
Fair Value Disclosures [Text Block]	3. Fair Value Measurements The Company measures certain financial assets and liabilities at fair value on a recurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three-tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Inputs other than quoted prices included within Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. As of December 31, 2023 and 2022, the Company’s cash equivalents were all categorized as Level 1 and consisted of money market funds. As of December 31, 2023 and 2022, there were no no

Note 4 - Inventories

Note 4 - Inventories	12 Months Ended
Note 4 - Inventories	Dec. 31, 2023
Notes to Financial Statements
Inventory Disclosure [Text Block]	4. Inventories Inventories consisted of the following (in thousands): December 31, 2023 2022 Raw materials $ 3,203 $ 3,374 Work-in-process 25 17 Finished products 2,070 1,574 Total inventories $ 5,298 $ 4,965

Note 5 - Property and Equipment

Note 5 - Property and Equipment, Net	12 Months Ended
Note 5 - Property and Equipment, Net	Dec. 31, 2023
Notes to Financial Statements
Property, Plant and Equipment Disclosure [Text Block]	5. Property and Equipment, Net Property and equipment, net, consisted of the following (in thousands): December 31, 2023 2022 Equipment held by customers and field sales personnel $ 2,495 $ 2,566 Machinery and equipment 1,379 1,372 Computer software 122 122 Computer equipment 200 200 Furniture and fixture 78 78 Leasehold improvements 320 320 Total property and equipment, gross 4,594 4,658 Less: Accumulated depreciation and amortization (4,107 ) (3,956 ) Total property and equipment, net $ 487 $ 702 Depreciation expense for the years ended December 31, 2023 and 2022, was approximately $289,000 and $196,000, respectively. Property and equipment include certain equipment that is leased to customers and located at customer premises. Also, included is equipment held by the Company’s field sales personnel for use in cases with customers. The Company retains ownership of the equipment held for evaluation by customers and has the right to remove the equipment if it is not being utilized according to expectations. Depreciation expense relating to the leased equipment held by customers and those held by the Company’s field sales personnel of $208,000 and $119,000 was recorded in cost of revenues during the years ended December 31, 2023 and 2022, respectively. The net book value of this equipment was $385,000 and $527,000 at December 31, 2023 and December 31, 2022, respectively.

Note 6 - Accrued Expenses and O

Note 6 - Accrued Expenses and Other Current Liabilities	12 Months Ended
Note 6 - Accrued Expenses and Other Current Liabilities	Dec. 31, 2023
Notes to Financial Statements
Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block]	6. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following (in thousands): December 31, 2023 2022 Accrued product warranty costs $ 193 $ 109 Deferred revenue 172 141 Accrued professional fees 152 60 Accrued clinical trial costs 105 106 Accrued travel and entertainment expenses 88 129 Accrued sales and use tax 44 40 Other accrued liabilities 63 72 Total accrued expenses and other current liabilities $ 817 $ 657

Note 7 - Borrowings

Note 7 - Borrowings	12 Months Ended
Note 7 - Borrowings	Dec. 31, 2023
Notes to Financial Statements
Debt Disclosure [Text Block]	7. Borrowings CRG On September 22, 2015, the Company entered into a Term Loan Agreement, as amended (the “Loan Agreement”) with CRG under which, subject to certain conditions, the Company had the right to borrow up to $50 million in principal amount from CRG on or before the end of the twenty-fourth (24 th On February 14, 2018, the Company and CRG further amended the Loan Agreement concurrent with the conversion of $38 million of the principal amount of the senior secured term loan (plus $3.8 million in back-end fees and prepayment premium applicable thereto) into a newly authorized Series A convertible preferred stock. On August 2, 2023, the Company and CRG entered into a Securities Purchase Agreement (“SPA”) pursuant to which the Company issued 1,920 shares of a newly authorized Series E convertible preferred stock (“Series E preferred stock”) in exchange for CRG surrendering for cancellation $1.92 million of outstanding principal and accrued interest of the senior secured term loan under the Loan Agreement (the “Term Loan Agreement”). Each share of Series E preferred stock has a stated value of $1,000 per share and is convertible into 93 shares of the Company’s common stock at a conversion price of $10.725 per share, provided that the shares of Series E preferred stock cannot be converted into common stock to the extent the applicable holder would beneficially own in excess of 19.99% of the Company’s outstanding voting power, unless approved by the Company's stockholders in accordance with Nasdaq Listing Rule 5635(b). The Company has entered into several amendments to the Loan Agreement (the “Amendments”) with CRG since September 2015. The Amendments, among other things: (1) extended the interest-only period through December 31, 2026; (2) extended the period during which the Company may elect to pay a portion of interest in payment-in-kind (“PIK”), interest payments through December 31, 2026 so long as no Default (as defined in the Loan Agreement) has occurred and is continuing; (3) permitted the Company to make the entire interest payments in PIK interest payments for through December 31, 2026 so long as no Default has occurred and is continuing; (4) extended the Stated Maturity Date (as defined in the Loan Agreement) to December 31, 2025; (5) reduced the minimum liquidity covenant to $3.5 million at all times; (6) eliminated the minimum revenue covenants for all years (7) changed the date under the on-going stand-alone representation regarding no “Material Adverse Change” to December 31, 2020; (8) amended the on-going stand-alone representation and stand-alone Event of Default (as defined in the Loan Agreement) regarding Material Adverse Change such that any adverse change in or effect upon the revenue of the Company and its subsidiaries due to the outbreak of COVID-19 will not constitute a Material Adverse Change; (9) provided CRG with board observer rights and (10) provide that the board observer may be appointed or removed by written notice from the Majority Lenders (as defined in the Loan Agreement). On January 26, 2024, the Company entered into Amendment No. 7 to the Loan Agreement with CRG, which reduces the minimum liquidity requirement of the Loan Agreement from $3.5 million to $1.0 million until April 1, 2024. Thereafter, the Company will be subject to the minimum liquidity requirement of $3.5 million. On March 5, 2024, the Company entered into Amendment No. 9 to the Loan Agreement with CRG, which (1) extended the interest-only period through December 31, 2026; (2) extended the period during which the Company may elect to pay a portion of interest in payment-in-kind (“PIK”), interest payments through December 31, 2026 so long as no Default (as defined in the Loan Agreement) has occurred and is continuing; (3) permitted the Company to make the entire interest payments in PIK interest payments for through December 31, 2026 so long as no Default has occurred and is continuing; and (4) permit the payment of dividends on the preferred stock issued or issuable to the Purchaser, as defined in Note 14. Refer therein for details. Under the amended Loan Agreement, no cash payments for either principal or interest are required until the first quarter of 2024. The interest will be accrued and included in the debt balance based (to the extent not paid) on principal amounts outstanding at the beginning of the quarter at an interest rate of 12.5%. Beginning in the first quarter of 2024, the Company will be required to make quarterly principal payments (in addition to the interest) of $1.6 million with total principal payments of $6.5 million in 2024 and $6.5 million in 2025. The maturity date of the Loan (as defined in the Loan Agreement) is December 31, 2025. The Company may voluntarily prepay the borrowings in full, with a prepayment premium beginning at 5.0% and declining by 1.0% annually thereafter, with no premium being payable if prepayment occurs after seven and half years of the loan. Each tranche of borrowing required the payment, on the borrowing date, of a financing fee equal to 1.5% of the borrowed loan principal, which is recorded as a discount to the debt. In addition, a facility fee equal to 15.0% of the amounts borrowed plus any PIK is to be payable at the end of the term or when the borrowings are repaid in full. A long-term liability is being accreted using the effective interest method for the facility fee over the term of the Loan Agreement with a corresponding discount to the debt. The borrowings are collateralized by a security interest in substantially all of the Company’s assets. The Loan Agreement requires that the Company adheres to certain affirmative and negative covenants, including financial reporting requirements, certain minimum financial covenants for pre-specified liquidity and a prohibition against the incurrence of indebtedness, or creation of additional liens, other than as specifically permitted by the terms of the Loan Agreement. In particular, the covenants of the amended Loan Agreement included a covenant that the Company maintain a minimum of $3.5 million of cash and certain cash equivalents. The minimum liquidity requirement was temporarily reduced to $1.0 million until April 1, 2024. In addition, the Loan Agreement prohibits the payment of cash dividends on the Company’s capital stock and also places restrictions on mergers, sales of assets, investments, incurrence of liens, incurrence of indebtedness and transactions with affiliates. CRG may accelerate the payment terms of the Loan Agreement upon the occurrence of certain “Events of Default” set forth therein, which include the failure of the Company to make timely payments of amounts due under the Loan Agreement, the failure of the Company to adhere to the covenants set forth in the Loan Agreement, the insolvency of the Company or upon the occurrence of a “Material Adverse Change” thereunder. As of December 31, 2023, the Company was in compliance with all applicable covenants under the Loan Agreement. As of December 31, 2023, principal, final facility fee and PIK payments under the Loan Agreement, as amended, were as follows (in thousands): Year Ending December 31, 2024 $ 7,827 2025 9,113 Total 16,940 Less: Amount of PIK additions and final facility fee to be incurred subsequent to December 31, 2023 (2,481 ) Less: Amount representing debt issuance costs (166 ) Borrowings, current portion, as of December 31, 2023 $ 14,293 In connection with drawdowns under the Loan Agreement, the Company recorded aggregate debt discounts of $1.3 million as contra-debt. The debt discounts are being amortized as non-cash interest expense using the effective interest method over the term of the Loan Agreement. As of December 31, 2023 and 2022, the balance of the aggregate debt discount was approximately $166,000 and $249,000, respectively. The Company’s interest expense associated with the amortization of debt discount was approximately $83,000 during each of the years ended December 31, 2023 and 2022. The Company incurred total interest expense of approximately $2.0 million and $1.9 million during the years ended December 31, 2023 and 2022, respectively. While, as of the date hereof, CRG has not purported that an Event of Default has resulted due to a Material Adverse Change (those terms as defined in the Loan Agreement), due to the substantial doubt about the Company’s ability to continue operating as a going concern, the entire outstanding amount of borrowings under the Loan Agreement and associated aggregate debt discount at December 31, 2023 were classified as current in these financial statements.

Note 8 - Leases

Note 8 - Leases	12 Months Ended
Note 8 - Leases	Dec. 31, 2023
Notes to Financial Statements
Lessee, Operating Leases [Text Block]	8. Leases The Company’s operating lease obligations primarily consist of leased office, laboratory, and manufacturing space under a non-cancelable operating lease. In addition to the minimum future lease commitments presented below, the lease requires the Company to pay property taxes, insurance, maintenance, and repair costs. The lease includes a rent holiday concession and escalation clauses for increased rent over the lease term. Rent expense is recognized using the straight-line method over the term of the lease. The lease will expire on November 30, 2024. The Company is obligated to pay approximately $5.8 million in base rent payments through November 2024, beginning on December 1, 2019. The weighted average remaining lease term as of December 31, 2023 is 0.9 years. On March 6, 2024, the Company entered into an amendment to the lease which extended the lease term for a period of one year, subsequent to the original expiration of November 30, 2024. As amended, the lease will expire on November 30, 2025. Under the terms of the amendment, the Company will be obligated to pay approximately $1.3 million in base rent payments through November 2025, beginning on December 1, 2024. This amendment also provides an optional one year extension of the lease following the end of the current term, as amended. The operating lease was included on the balance sheet at the present value of the future base payments discounted at a 6.5% discount rate using the rate of interest that the Company would have to pay to borrow on a collateralized basis over a similar term and amount equal to the lease payments in a similar economic environment as the lease does provide an implicit rate. The Company’s operating lease expense, excluding variable maintenance fees and other expenses on a monthly basis, was approximately $105,000. Rent expense for each of the years ended December 31, 2023 and 2022 was approximately $1.3 million. The Company’s variable expenses for the years ended December 31, 2023 and 2022 was approximately $0.4 million and $0.3 million, respectively. Operating right-of-use asset amortization was approximately $1.1 million for each of the years ended December 31, 2023 and 2022. Due to payments being made in excess of operating lease expense recognized, the Company recorded approximately $13,000 and $65,000 as prepaid rent included in other assets on the balance sheet as of December 31, 2023 and 2022, respectively. The following table presents the future operating lease payments and leasehold liability included on the balance sheet related to the Company’s operating lease as of December 31, 2023, excluding the March 2024 lease amendment (in thousands): Year Ending December 31, 2024 $ 1,138 Total 1,138 Less: Imputed interest (36 ) Leasehold liability as of December 31, 2023 $ 1,102 The following table shows ROU assets and lease liabilities, and the associated financial statement line items (in thousands): December 31, Lease-Related Assets and Liabilities Financial Statement Line Items 2023 2022 Right of use assets: Operating lease Right of use asset $ 1,102 $ 2,194 Total right of use assets $ 1,102 $ 2,194 Lease liabilities: Operating lease Leasehold liability, current portion $ 1,102 $ 1,092 Leasehold liability, long-term portion — 1,102 Total lease liabilities $ 1,102 $ 2,194

Note 9 - Commitments and Contin

Note 9 - Commitments and Contingencies	12 Months Ended
Note 9 - Commitments and Contingencies	Dec. 31, 2023
Notes to Financial Statements
Commitments and Contingencies Disclosure [Text Block]	9. Commitments and Contingencies Purchase Obligations Purchase obligations consist of agreements to purchase goods and services entered into in the ordinary course of business. The Company had non-cancelable commitments to suppliers for purchases totaling approximately $0.5 million as of December 31, 2023. The majority of this amount is related to commitments to purchase inventory components and services related to the manufacturing of inventory. Indemnification In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and may provide for indemnification of the counterparty. The Company’s exposure under these agreements is unknown because it involves claims that may be made against it in the future but have not yet been made. To date, the Company has not been subject to any claims or been required to defend any action related to its indemnification obligations. The Company indemnifies each of its directors and officers for certain events or occurrences, subject to certain limits, while the director is or was serving at the Company’s request in such capacity, as permitted under Delaware law and in accordance with its certificate of incorporation and bylaws. The term of the indemnification period lasts as long as a director may be subject to any proceeding arising out of acts or omissions of such director in such capacity. The maximum amount of potential future indemnification is unlimited; however, the Company currently holds director liability insurance. This insurance allows the transfer of risk associated with the Company’s exposure and may enable it to recover a portion of any future amounts paid. The Company believes that the fair value of these indemnification obligations is minimal. Accordingly, it has not recognized any liabilities relating to these obligations for any period presented. Legal Proceedings The Company is not currently involved in any pending legal proceedings that it believes could have a material adverse effect on our financial condition, results of operations or cash flows. From time to time, the Company may be involved in legal proceedings or investigations, which could harm our reputation, business and financial condition and divert the attention of our management from the operation of our business.

Note 10 - Stockholders' Equity

Note 10 - Stockholders' Equity	12 Months Ended
Note 10 - Stockholders' Equity	Dec. 31, 2023
Notes to Financial Statements
Equity [Text Block]	10. Stockholders Equity Convertible Preferred Stock As of December 31, 2023, the Company’s certificate of incorporation, as amended and restated, authorizes the Company to issue up to 5,000,000 shares of convertible preferred stock with $0.001 par value per share. As of December 31, 2023 and 2022, 62,881 and 60,961 shares, respectively, were issued and outstanding. Series A Convertible Preferred Stock The holders of Series A preferred stock are entitled to receive annual accruing dividends at a rate of 8%, payable in additional shares of Series A preferred stock or cash, at the Company’s option. The shares of Series A preferred stock have a liquidation preference of $1,000 per share and carry no voting rights. During the year ended December 31, 2022, 4,510 of additional shares were issued to CRG as payment of dividends. As of December 31, 2023 and 2022, 60,876 and 60,876 shares of Series A preferred stock were outstanding, respectively, which are currently convertible into shares of the Company’s common stock at $6,000 per share. The Series A preferred stock accrued no On September 29, 2023, the Company entered into a waiver agreement (the “Waiver Agreement”) with CRG, who hold all of the outstanding shares of the Company’s Series A preferred stock. Pursuant to the Waiver Agreement, CRG waived their rights to receive the Series A preferred dividend for the year ending December 31, 2023. Such waived preferred dividends are not cumulative or accrued. Consequently, there were no Series A preferred stock dividends recorded during the year ended December 31, 2023. Series B Convertible Preferred Stock The Series B preferred stock has a liquidation preference of $0.001 per share, full ratchet price based anti-dilution protection, has no voting rights and is subject to certain ownership limitations. The Series B preferred stock is immediately convertible at the option of the holder, has no stated maturity, and does not pay regularly stated dividends or interest. As of December 31, 2023 and 2022, 85 shares of Series B preferred stock remained outstanding, which are currently convertible into shares of the Company’s common stock at $5.732 per share. Series D Convertible Preferred Stock On January 14, 2022, the Company entered into a security purchase agreement with several institutional investors, pursuant to which the Company agreed to sell and issue, in a registered direct offering (“January 2022 Offering”), an aggregate of 7,600 shares of the Company’s Series D convertible preferred stock, par value $0.001 per share at an offering price of $1,000 per share. Concurrently, the Company agreed to issue to these investors warrants to purchase up to an aggregate of 53,833 shares of the Company’s common stock (the “Common Warrants”). The shares of Series D preferred stock had a stated value of $1,000 per share and were convertible into an aggregate of 63,333 shares of common stock at a conversion price of $120.00 per share. During the year ended December 31, 2022, all 7,600 shares of Series D preferred stock were converted into a total of 63,333 shares of common stock. There are no shares of Series D preferred stock outstanding as of December 31, 2023. At the time of issuance, the Company evaluated the classification of the Series D preferred stock and determined equity classification was appropriate due to no mandatory or contingently redeemable redemption features. The warrants issued to the investors were considered freestanding equity classified instruments. The Company first allocated gross proceeds from the registered direct offering between the preferred stock and the warrants issued to investors using a relative fair value approach, resulting in an initial allocation to each instrument of $4.0 million and $3.6 million, respectively. On the issuance date, the Company estimated the fair value of the Common Warrants issued to investors and warrants issued to the placement agent designees using a Black-Scholes option pricing model using the following assumptions: (i) contractual term of 5.5 years, (ii) expected volatility rate of 136.61%, (iii) risk-free interest rate of 1.51%, (iv) expected dividend rate of 0%, and (v) closing price of the Company’s common stock of the day immediately preceding the registered direct offering. The fair value of preferred stock was estimated based upon equivalent common shares that preferred stock could have been converted into at the closing price of the day immediately preceding the purchase date. The embedded conversion feature was evaluated and bifurcation from the preferred stock equity host was not considered necessary. The issuance of the Series D convertible preferred stock generated a beneficial conversion feature (“BCF”) which arose as the equity security was issued with an embedded conversion option that is beneficial to the investor or in the money at inception because the conversion option has an effective conversion price that is less than the market price of the underlying stock at the commitment date. The Company recorded the BCF as a discount to the preferred stock resulting in the amount of $5.1 million based on the intrinsic value of the beneficial conversion. As the preferred stock was immediately convertible into common stock subject to the consummation of the reverse stock split on March 14, 2022, a deemed dividend related to the discount associated with the beneficial conversion feature was recorded on that date. This one-time, non-cash charge impacted net loss applicable to common stockholders and net loss per share attributable to common stockholders for the year ended December 31, 2022. Series E Convertible Preferred Stock On August 2, 2023, the Company entered into a Series E Purchase Agreement with CRG, pursuant to which it agreed to surrender $1.92 million of the outstanding principal and accrued interest of its senior secured term loan into Series E preferred stock. Each share of Series E preferred stock has a stated value of $1,000 per share and is convertible into 93 shares of the Company’s common stock at a conversion price of $10.725 per share. The Series E preferred stock is initially convertible into 178,560 shares of common stock subject to certain limitations contained in the Series E Purchase Agreement. Shares of Series E preferred stock cannot be converted into common stock to the extent the applicable holder would beneficially own in excess of 19.99% of the Company’s outstanding voting power, unless approved by the Company's stockholders in accordance with Nasdaq Listing Rule 5635(b). Under the terms of the Series E Purchase Agreement, the holders of Series E preferred stock are entitled to receive annual accruing dividends at a rate of 8%, payable in additional shares of Series E preferred stock or cash, at the Company’s option. The shares of Series E preferred stock have full voting rights, on an as-converted basis, subject to certain limitations. The Series E preferred stock rank senior to all other classes and series of the Company’s equity in terms of repayment and certain other rights. As of December 31, 2023, 1,920 shares of Series E preferred stock were outstanding. On September 29, 2023, the Company entered into the Waiver Agreement with CRG, who hold all of the outstanding shares of the Company’s Series E preferred stock. Pursuant to the Waiver Agreement, CRG waived their rights to receive the Series E preferred dividend for the year ending December 31, 2023. Such waived preferred dividends are not cumulative or accrued. Consequently, there were no Series E preferred stock dividends recorded during the year ending December 31, 2023. Common Stock At December 31, 2023, the Company’s certificate of incorporation, as amended and restated, authorizes the Company to issue up to 100,000,000 shares of common stock with $0.001 par value per share, of which 1,279,928 shares were issued and outstanding. Common Stock Warrants As of December 31, 2023, the Company had outstanding warrants to purchase common stock as follows: Total Outstanding and Exercisable Underlying Shares of Common Stock Exercise Price per Share Expiration Date Series 1 Warrants issued in the February 2018 Series B financing 8,979,000 2,993 $ 6,000.00 February 2025 Series 2 Warrants issued in the February 2018 Series B financing 8,709,500 2,903 $ 6,000.00 February 2025 Placement agent warrants issued in the January 2022 financing 1,330,000 4,433 $ 150.00 January 2027 Warrants issued in the January 2022 financing 16,150,000 53,833 $ 144.00 July 2027 Series A Preferred Investment Options issued in August 2022 financing 2,853,883 190,259 $ 22.53 February 2028 Series B Preferred Investment Options issued in August 2022 financing 2,853,883 190,259 $ 22.53 August 2024 Placement agent Preferred Investment Options issued in the August 2022 financing 171,233 11,416 $ 32.85 August 2027 Total as of December 31, 2023 41,047,499 456,096 As of December 31, 2022, the Company had outstanding warrants to purchase common stock as follows: Total Outstanding and Exercisable Underlying Shares of Common Stock Exercise Price per Share Expiration Date Series 1 Warrants issued in the February 2018 Series B financing 8,979,000 2,993 $ 6,000.00 February 2025 Series 2 Warrants issued in the February 2018 Series B financing 8,709,500 2,903 $ 6,000.00 February 2025 Warrants issued in the November 2018 financing 8,768,395 2,923 $ 1,200.00 November 2023 Placement agent warrants issued in the January 2022 financing 1,330,000 4,433 $ 150.00 January 2027 Warrants issued in the January 2022 financing 16,150,000 53,833 $ 144.00 July 2027 Pre-funded warrants issued in the August 2022 financing 91,324 91,324 $ 0.0001 n/a Series A Preferred Investment Options issued in August 2022 financing 2,853,883 190,259 $ 22.53 February 2028 Series B Preferred Investment Options issued in August 2022 financing 2,853,883 190,259 $ 22.53 August 2024 Placement agent Preferred Investment Options issued in the August 2022 financing 171,233 11,416 $ 32.85 August 2027 Total as of December 31, 2022 49,907,218 550,343 January 2022 Offering Pursuant to a purchase agreement entered into on January 14, 2022, the Company issued warrants to purchase up to an aggregate of 53,833 shares of the Company’s common stock at an exercise price of $144.00 per share and which became exercisable beginning July 14, 2022. The Common Warrants will expire five The Company issued to the placement agent of the January 2022 Offering warrants to purchase up to an aggregate of 4,433 shares of common stock (the “Placement Agent Warrants”). The Placement Agent Warrants are subject to the same terms as the Common Warrants, except that the Placement Agent Warrants have an exercise price of $150.00 per share and a term of five August 2022 Offering Pursuant to a purchase agreement entered into on August 4, 2022, the Company issued, in a registered direct offering, Pre-Funded Warrants to purchase up to 52,268 shares of common stock (the “RD Pre-Funded Warrants”) and, in a concurrent private placement, Pre-Funded Warrants to purchase up to 91,324 shares of common stock (the “Private Placement Pre-Funded Warrants” and together with the RD Pre-Funded Warrants the “August 2022 Pre-Funded Warrants”). The August 2022 Pre-Funded Warrants have an exercise price of $0.0001 per share, are immediately exercisable, and have no expiration date. During the year ended December 31, 2022, 52,268 of shares of RD Pre-Funded Warrants were exercised into the equivalent number of the Company’s common stock. During the year ended December 31, 2023, all the remaining 91,324 Private Placement Pre-Funded Warrants were exercised. Consequently, no Also in the August 2022 Offering, the Company issued Series A preferred investment options to purchase up to 190,259 additional shares of the Company’s common stock and Series B preferred investment options to purchase up to 190,259 additional shares of the Company’s common stock, collectively referred to as Preferred Investment Options. The Series A preferred investment options have an exercise price of $22.53 per share, are immediately exercisable, and will expire five two The Company also issued to the placement agent of the August 2022 Offering preferred investment options to purchase up to 11,416 shares of common stock (the “Placement Agent Preferred Investment Options”). The Placement Agent Preferred Investment Options are subject to the same terms as the Preferred Investment Options, except that the Placement Agent Preferred Investment Options have an exercise price of $32.85 per share and a term of five The exercise price and the number of shares of common stock issuable upon exercise of each Common Warrants, Preferred Investment Options, and Placement Agent Preferred Investment Options are subject to appropriate adjustments in the event of certain stock dividends and distributions, stock splits, stock combinations, reclassifications or similar events affecting the common stock. In addition, in certain circumstances, upon a fundamental transaction, a holder of Common Warrants, Preferred Investment Options, or Placement Agent Preferred Investment Options will be entitled to receive, upon exercise, the kind and amount of securities, cash or other property that such holder would have received had they exercised the Common Warrants, Preferred Investment Options, or Placement Agent Preferred Investment Options immediately prior to the fundamental transaction. The Common Warrants, Preferred Investment Options, and Placement Agent Preferred Investment Options can be exercised at the option of the holders at any time after they become exercisable provided that shares of the Common Warrants, Preferred Investment Options, or Placement Agent Preferred Investment Options cannot be exercised into common stock if the applicable holder would beneficially own in excess of 4.99% (or, upon election by such holder prior to the issuance of any shares of Common Warrants, Preferred Investment Options, or Placement Agent Preferred Investment Options, 9.99%) of the Company’s outstanding common stock immediately after giving effect to the exercise. A holder of the Common Warrants, Preferred Investment Options or Placement Agent Preferred Investment Options may, upon notice to the Company, increase or decrease such beneficial ownership limitation, but not in excess of 9.99%. In the event of a fundamental transaction in which the holders of our voting securities immediately prior to such fundamental transaction will not, following such fundamental transaction, directly or indirectly own more than 50% of the voting securities of the surviving entity or successor entity, and in which the Company is not the successor entity or does not continue as a reporting issuer under the Exchange Act, then, at the request of the holder, the Company or the successor entity shall purchase the unexercised portion of the Common Warrants, Preferred Investment Options, and Placement Agent Preferred Investment Options from the holder by paying to the holder an amount, in cash, equal to the fair value of the remaining unexercised portion of the Common Warrants, Preferred Investment Options, and Placement Agent Preferred Investment Options on the date of such fundamental transaction, subject to certain limitations in the event of a fundamental transaction not within our control. As of December 31, 2023 and 2022, warrants and preferred investment options to purchase an aggregate of 456,096 and 550,343 shares of common stock were outstanding, respectively, all of which were classified within the equity section of the respective balance sheets. During the year ended December 31, 2023 the 8,768,395 warrants shares issued in connection with the November 2018 financing expired unexercised.

Note 11 - Stock-based Compensat

Note 11 - Stock-based Compensation	12 Months Ended
Note 11 - Stock-based Compensation	Dec. 31, 2023
Notes to Financial Statements
Share-Based Payment Arrangement [Text Block]	11. Stock-Based Compensation Stock Plans In January 2015, the Board of Directors adopted and the Company’s stockholders approved the 2015 Equity Incentive Plan (“2015 Plan”). On October 14, 2022, the Company’s stockholders approved an additional 116,667 shares of common stock for issuance under the 2015 Plan. The following year on December 22, 2023, the Company’s stockholders approved an additional 300,000 shares of common stock for issuance under the 2015 Plan, which was later registered in an S-8 registration statement filed on January 10, 2024. The 2015 Plan provides for the grant of incentive stock options (“ISOs”) to employees and for the grant of non-statutory stock options (“NSOs”), restricted stock, restricted stock awards (“RSAs”), restricted stock units (“RSUs”), stock appreciation rights, performance units and performance shares to employees, directors and consultants. As of December 31, 2023, 24,890 shares were available for grant under the 2015 Plan. Pursuant to the 2015 Plan, ISOs and NSOs may be granted with exercise prices at not less than 100% of the fair value of the common stock on the date of grant and the exercise price of ISOs granted to a stockholder, who, at the time of grant, owns stock representing more than 10% of the voting power of all classes of the stock of the Company, shall be not less than 110% of the fair market value per share of common stock on the date of grant. The Company’s Board of Directors determines the vesting schedule of the options. Stock option activity under the Plans is set forth below: Number of (in thousands) Weighted Average Price Weighted Average Remaining Contractual Life (in years) Intrinsic Value (in thousands) Balance at December 31, 2022 15 $ 183,340.00 4.02 $ — Balance at December 31, 2023 15 $ 183,340.00 3.29 $ — Exercisable at December 31, 2023 15 $ 183,340.00 3.29 $ — Vested and expected to vest at December 31, 2023 15 $ 183,340.00 3.29 $ — Additional information related to the Company’s stock options as of December 31, 2023 is summarized as follows: Options Outstanding Options Vested Weighted Average Remaining Weighted Weighted Contractual Average Average Exercise Options Life (in Exercise Number Exercise Price Outstanding years) Price Exercisable Price $ 5,010.00 10 4.44 $ 5,010.00 10 $ 5,010.00 $ 540,000.00 5 1.00 $ 540,000.00 5 $ 540,000.00 15 3.29 $ 183,340.00 15 $ 183,340.00 There were no not The Company’s RSUs and RSAs generally vest annually over two Number of Shares Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term (in years) Awards outstanding at December 31, 2021 668 $ 363.45 0.72 Released (572 ) $ 372.85 Forfeited (68 ) $ 362.12 Awards outstanding at December 31, 2022 28 $ 174.60 0.17 Awarded 100,189 $ 18.45 Released (2,294 ) $ 20.36 Forfeited (7,733 ) $ 18.45 Awards outstanding at December 31, 2023 90,190 $ 18.45 1.04 As of December 31, 2023, there was $0.8 million of remaining unamortized stock-based compensation expense associated with RSAs, which will be expensed over a weighted average remaining service period of 1.0 year. The outstanding non-vested and expected to vest RSAs at December 31, 2023 have an aggregate fair value of approximately $0.2 million. The Company used the closing market price of $2.71 per share at December 29, 2023 to determine the aggregate fair value for the RSAs outstanding at that date. For the years ended December 31, 2023 and 2022, the fair value of the RSAs and RSUs vested was approximately $42,000 and $14,000, respectively. For the years ended December 31, 2023 and 2022, stock-based compensation expense recognized associated with the vesting of RSAs and RSUs was approximately $0.9 million and $0.1 million, respectively. Total noncash stock-based compensation expense relating to the Company’s RSAs and RSUs recognized, before taxes, during the years ended December 31, 2023 and 2022, is as follows (in thousands): Year Ended December 31, 2023 2022 Cost of revenues $ 134 $ 18 Research and development expenses 200 37 Selling, general and administrative expenses 606 72 $ 940 $ 127

Note 12 - Income Taxes

Note 12 - Income Taxes	12 Months Ended
Note 12 - Income Taxes	Dec. 31, 2023
Notes to Financial Statements
Income Tax Disclosure [Text Block]	12. Income Taxes For the years ended December 31, 2023 and 2022, the Company’s provision for income taxes consisted of zero Year Ended December 31, 2023 2022 Tax at federal statutory rate $ (3,847 ) $ (3,701 ) State taxes, net of federal benefit 59 (916 ) Permanent differences 355 (484 ) Change in valuation allowance 3,382 5,084 Research credits (103 ) (273 ) Nondeductible interest expense 154 290 Other — — Provision for taxes $ — $ — Significant components of the Company’s net deferred tax assets as of December 31, 2023 and 2022 consist of the following (in thousands): As of December 31, 2023 2022 Deferred tax assets: Federal, state and foreign net operating losses $ 87,568 $ 85,547 Research and other credits 5,546 5,343 Operating lease liability 275 544 Fixed assets 517 471 Accruals and other 3,842 3,628 Capitalized research and development 1,888 1,019 Total deferred tax assets 99,636 96,552 Less: Valuation allowance (99,358 ) (95,992 ) Total net deferred tax assets 278 560 Deferred liabilities: Property and equipment — — ) Operating lease right of use asset (278 ) (560 ) Total deferred tax liabilities (278 ) (560 ) Net deferred tax assets (liabilities) $ — $ — The valuation allowance increased by $3.4 million and $5.1 million during the years ended December 31, 2023 and 2022, respectively. As of December 31, 2023, the Company had approximately $355.7 million of federal and $217.1 million of state net operating loss carryforwards available to offset future taxable income. If not utilized, the federal and state net operating loss carryforwards begin to expire in 2027 and 2024, respectively. Out of the Federal net operating loss carryforwards, $98.2 million were generated post December 31, 2017 and have no expiration. As of December 31, 2023, the Company also had approximately $4.5 million and $4.4 million of research and development tax credit carryforwards available to reduce future taxable income, if any, for both federal and California purposes, respectively. The federal credit carryforwards expire beginning in 2027, and the California research credits do not expire and may be carried forward indefinitely. The Company's ability to utilize the net operating loss and tax credit carryforwards in the future may be subject to substantial restrictions in the event of past or future ownership changes as defined in Section 382 of the Internal Revenue Code and similar state tax laws. In the event the Company should experience an ownership change, as defined, utilization of the Company's net operating loss carryforwards and tax credits could be limited. The Company evaluates tax positions for recognition using a more-likely-than-not recognition threshold, and those tax positions eligible for recognition are measured as the largest amount of tax benefit that is greater than 50% likely of being realized upon the effective settlement with a taxing authority that has full knowledge of all relevant information. A reconciliation of the beginning and ending amount of the gross recognized tax benefit is as follows (in thousands): As of December 31, 2023 2022 Balance at beginning of year $ 2,581 $ 2,366 Increase based on the tax positions in the current year 216 203 Increase (Decrease) for tax positions of prior year (118 ) 12 Balance at end of year $ 2,679 $ 2,581 As of December 31, 2023, all unrecognized tax benefits would be subject to a full valuation allowance, if recognized, and would not affect the Company’s tax rate. The Company does not anticipate that the total amounts of unrecognized tax benefits will significantly increase or decrease in the next twelve months. The Company's policy is to include interest and penalties related to unrecognized tax benefits within its provision for income taxes. Due to the Company's net operating loss position, the Company has not

Note 13 - 401(k) Plan

Note 13 - 401(k) Plan	12 Months Ended
Note 13 - 401(k) Plan	Dec. 31, 2023
Notes to Financial Statements
Retirement Benefits [Text Block]	13. 401(k) Plan The Company has a qualified retirement plan under section 401(k) of the Internal Revenue Code (“IRC”) under which participants may contribute up to 99% of their eligible compensation, subject to maximum deferral limits specified by the IRC. The Company may make a discretionary matching contribution to the 401(k) plan, and may make a discretionary employer contribution to each eligible employee each year. To date, the Company has made no

Note 14 - Subsequent Events

Note 14 - Subsequent Events	12 Months Ended
Note 14 - Subsequent Events	Dec. 31, 2023
Notes to Financial Statements
Subsequent Events [Text Block]	14. Subsequent Events Restricted Stock Awards Granted On January 11, 2024, the Company granted a total of 76,791 shares of RSAs to the Company’s non-employee directors. This granting of RSAs represents the 2023 annual equity grants pursuant to the Company’s Outside Director Compensation Policy which entitles each non-employee director to receive equity compensation having a grant date fair value equal to $75,000 annually. These RSAs fully vest one Retention Bonus Payments and resulting Restricted Stock Award Grants In satisfaction of certain retention bonus payment obligations for a number of employees which include among others, Jeffrey M. Soinski, Chief Executive Officer and Himanshu Patel, Chief Technology Officer, the Company paid a total of $0.9 million in the form of RSAs on January 16, 2024. Pursuant to the retention bonus terms as approved by the Compensation Committee (the “Committee”) of the Board of Directors on March 9, 2021, the Company may elect to pay these incentive payments in either cash or equity, or a combination of both. On January 11, 2024, the Committee approved the aforementioned payment in the form of RSAs. Specifically, the Company granted a total of 317,314 shares of RSAs which vested immediately upon grant. To satisfy all associated income and other statutory tax obligations on behalf of the employees, the Company employed a withhold-to-cover payment method. Consequently, 123,285 RSA shares were withheld resulting in a net issuance of common shares to employees totaling 194,029. The Company measured the fair value of RSAs using the closing stock price of a share of the Company’s common stock of $2.70 on the day of grant. The resulting expense will be offset against the reversal of the associated accrued compensation liability thereby resulting in little to no income statement effect during the quarter ended March 31, 2024. Strategic Partnership On March 4, 2024, the Company entered into a License and Distribution Agreement (the “License Agreement”) with Zylox-Tonbridge effective as of the Initial Closing (defined below), pursuant to which the Company will license and distribute certain of the Company’s products (including consumables) in the Greater China region, including mainland China, Hong Kong, Macao, and Taiwan (the “Territory”). Zylox-Tonbridge will lead all regulatory activities for the registration of the Avinger products in the Territory. Avinger will also license its intellectual property and know-how related to Avinger products to Zylox-Tonbridge so that Zylox-Tonbridge can manufacture the localized products in the Territory. Avinger will supply Avinger products to Zylox-Tonbridge until Zylox-Tonbridge’s manufacturing capability has been established and Zylox-Tonbridge has obtained the regulatory approval of the localized products manufactured by Zylox-Tonbridge. All sales of Avinger products locally manufactured by Zylox-Tonbridge with regulatory approval by the regulatory authorities in the Territory and commercialized in the Territory will be royalty bearing to Avinger at a rate from a mid-single to high-single digit percentage depending on the amount of gross revenue as defined in the License Agreement, with certain increases depending on the amount of product gross margin. The License Agreement has an initial term of 20 years, which shall be further automatically extended for additional 20-year terms, subject to certain conditions. The License Agreement may not be terminated by either party, other than for certain uncured material breaches or the other party’s insolvency. In connection with the License Agreement, on March 4, 2024, the Company and Zylox-Tonbridge also entered into a Strategic Cooperation and Framework Agreement in conjunction with the Initial Closing (the “Collaboration Agreement” and, together with the License Agreement, the “Strategic Collaboration”), which provides the opportunity for the Company to access certain Zylox-Tonbridge peripheral vascular products for distribution in the U.S. and Germany. The agreement also provides the option for Avinger to source finished goods inventory from Zylox-Tonbridge following registration of Zylox-Tonbridge’s manufacturing facility with the FDA. Financing Agreements On March 4, 2024, in connection with the Strategic Collaboration, the Company and Zylox-Tonbridge Medical Limited, a wholly-owned subsidiary of Zylox-Tonbridge (the “Purchaser”), entered into a Securities Purchase Agreement (the “Purchase Agreement”), pursuant to which the Purchaser agreed to purchase, in two tranches, up to an aggregate of $15 million in shares of the Company’s common stock, par value $0.001 per share (the “Common Stock”), and shares of two new series of the Company’s preferred stock (the “Private Placement”). On March 5, 2024, (the “Initial Closing”), the Company issued to the Purchaser 75,327 shares of the Common Stock at a purchase price per share of $3.664 (the “Purchase Price”), and 7,224 shares of a newly authorized Series F convertible preferred stock, par value $0.001 per share (the “Series F Preferred Stock”), at a purchase price per share of $1,000, for an aggregate purchase price of $7.5 million. Each share of Series F Preferred Stock has a stated value of $1,000 and is initially convertible into approximately 273 shares of Common Stock at a conversion price equal to the Purchase Price, subject to the terms of the Certificate of Designation of Preferences, Rights, and Limitations of the Series F Preferred Stock (the “Series F Certificate of Designation”). Upon completion of the following as mutually agreed upon by the Company and the Purchaser: (i) the successful registration and listing under 21 CFR part 807 with the FDA of the Purchaser and one of its designated affiliates to manufacture Avinger’s products, and (ii) the Company achieving an aggregate of $10 million in gross revenue within any four consecutive fiscal quarters after the Initial Closing, excluding any gross revenue achieved by Avinger under the License Agreement discussed above (together, the “Milestones”), the Purchaser will invest an additional $7.5 million (the “Milestone Closing”) to purchase shares of the Company new Series G convertible preferred stock, par value $0.001 per share (the “Series G Preferred Stock”). Each share of Series G Preferred Stock will have a stated value of $1,000 and will be convertible into shares of Common Stock at a conversion price of equal to the lowest of (x) the Purchase Price, (y) the closing price of the Common Stock on the date immediately preceding the Milestone Closing, and (z) the average of the closing price for the last five trading days preceding the Milestone Closing, provided that the conversion price will be no less than $0.20. The Company’s obligations to (i) accept conversion of the shares of Series F Preferred Stock in excess of 19.99% of the Company’s outstanding common stock as of the date of the Purchase Agreement and (ii) issue and sell shares of Series G Preferred Stock upon completion of the Milestones are each subject to receipt of the approval of the Company’s stockholders as is necessary under the rules and regulations of Nasdaq (including, without limitation, Nasdaq Rule 5635(d)). Series A Preferred Stock Exchange In connection with the Strategic Collaboration and the Private Placement, on March 5, 2024, the Company entered into a Securities Purchase Agreement (the “A-1 Securities Purchase Agreement”) with CRG to exchange all outstanding shares of its Series A preferred stock for 10,000 shares of Series A-1 preferred stock (the “Exchange”). Among other things, the shares of Series A-1 preferred stock: (i) are convertible into an aggregate of approximately 2,729,257 shares of common stock at a conversion price equal to the Purchase Price, (ii) do not accrue or pay dividends payable solely on the Series A-1 preferred stock, (iii) will have no liquidation preference and (iv) will be junior in rank to shares of the Company’s Series E preferred stock, Series F preferred stock and Series G preferred stock. CRG Loan Amendment In connection with the Strategic Collaboration and the Private Placement, the Company also agreed to enter into Amendment No. 9 to Loan Agreement effective as of the Initial Closing (the “Amendment”) with CRG, which amends the Loan Agreement to, among other things: - extend the interest-only period through December 31, 2026; - provide that interest payable through December 31, 2026 may be payable in kind rather than in cash; and - permit the payment of dividends on the preferred stock issued or issuable to the Purchaser. Lease Extension On March 6, 2024, the Company entered into an amendment to the lease which extended the lease term for a period of one one

Significant Accounting Policies

Significant Accounting Policies (Policies)	12 Months Ended
Significant Accounting Policies (Policies)	Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	Basis of Presentation The accompanying financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). On March 11, 2022, the Company’s Board of Directors approved an amendment to the Company’s amended and restated certificate of incorporation to effect a 1-for-20 reverse stock split of the Company’s issued and outstanding common stock. The reverse stock split became effective on March 14, 2022. On September 8, 2023, the Company’s Board of Directors approved an amendment to the Company’s amended and restated certificate of incorporation to effect a 1-for-15 reverse stock split of the Company’s issued and outstanding common stock. The reverse stock split became effective on September 12, 2023. The par value of the common stock and preferred stock was not adjusted as a result of the reverse stock splits. All common stock, stock options, restricted stock units, restricted stock awards and per share amounts in the financial statements have been retroactively adjusted for all periods presented to give effect to the reverse stock splits. Additionally, the common stock at par and related additional paid-in capital amounts as of December 31, 2022 in the balance sheet, the common stock at par and related additional paid-in capital amounts in the Statement of Stockholders’ Equity as of December 31, 2022 and 2021, and for the year ended December 31, 2022 have also been retroactively reclassified to give effect to the reverse stock splits.
Use of Estimates, Policy [Policy Text Block]	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. Management uses significant judgment when making estimates related to its stock-based compensation, accruals related to compensation, the valuation of the common stock warrants, provisions for doubtful accounts receivable and excess and obsolete inventories, clinical trial accruals, and its reserves for sales returns and warranty costs. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.
Fair Value Measurement, Policy [Policy Text Block]	Fair Value of Financial Instruments The Company has evaluated the estimated fair value of its financial instruments as of December 31, 2023 and 2022. Financial instruments consist of cash and cash equivalents, accounts receivable and payable, and other current liabilities and borrowings. The carrying amounts of cash and cash equivalents, accounts receivable and payable, and other current liabilities approximate their respective fair values because of the short-term nature of those instruments. Based upon the borrowing terms and conditions currently available to the Company, the carrying values of the borrowings approximate their fair value.
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at the time of purchase to be cash equivalents. Cash equivalents are considered available-for-sale marketable securities and are recorded at fair value, based on quoted market prices. As of December 31, 2023 and 2022, the Company’s cash equivalents are entirely comprised of investments in money market funds. Any related unrealized gains and losses are recorded in other comprehensive income (loss) and included as a separate component of stockholders’ equity. There were no
Concentration of Credit Risk and Other Risks and Uncertainties [Policy Text Block]	Concentration of Credit Risk, and Other Risks and Uncertainties Financial instruments that potentially subject the Company to credit risk consist of cash and cash equivalents and accounts receivable to the extent of the amounts recorded on the balance sheets. The Company’s policy is to invest in cash and cash equivalents, consisting of money market funds. These financial instruments are held in Company accounts at one financial institution, First Citizens Bank, which acquired our prior banking partner, Silicon Valley Bank, in March 2023. The counterparties to the agreements relating to the Company’s investments consist of financial institutions of high credit standing. The Company provides for uncollectible amounts when specific credit problems arise. Management’s estimates for uncollectible amounts have been adequate, and management believes that all significant credit risks have been identified at December 31, 2023 and 2022. On March 10, 2023, the Federal Deposit Insurance Corporation announced that Silicon Valley Bank had been closed by the California Department of Financial Protection and Innovation. While we have regained access to our accounts at First Citizens Bank, formerly Silicon Valley Bank and are evaluating our banking relationships, future disruptions of financial institutions where we bank or have credit arrangements, or disruptions of the financial services industry in general, could adversely affect our ability to access our cash and cash equivalents. If we are unable to access our cash and cash equivalents as needed, our financial position and ability to operate our business will be adversely affected. The Company’s accounts receivable are due from a variety of healthcare organizations in the United States and select international markets. The Company provides for uncollectible amounts when specific credit problems arise. Management’s estimates for uncollectible amounts have been adequate, and management believes that all significant credit risks have been identified at December 31, 2023 and 2022. At December 31, 2023, there was one no one The Company manufactures its commercial products in-house, including the Pantheris and Ocelot family of catheters. Certain of the Company’s product components and sub-assemblies are manufactured by sole suppliers, including internally. Disruption in component or sub-assembly supply from these manufacturers or from in-house production would have a negative impact on the Company’s financial position and results of operations. The Company is subject to certain risks, including that its devices may not be approved or cleared for marketing by governmental authorities or be successfully marketed. There can be no assurance that the Company’s products will achieve widespread adoption in the marketplace, nor can there be any assurance that existing devices or any future devices can be developed or manufactured at an acceptable cost and with appropriate performance characteristics. The Company is also subject to risks common to companies in the medical device industry, including, but not limited to, new technological innovations, dependence upon third-party payors to provide adequate coverage and reimbursement, dependence on key personnel and suppliers, protection of proprietary technology, product liability claims, and compliance with government regulations. Existing or future devices developed by the Company may require approvals or clearances from the FDA or international regulatory agencies. In addition, in order to continue the Company’s operations, compliance with various federal and state laws is required. If the Company were denied or delayed in receiving such approvals or clearances, it may be necessary to adjust operations to align with the Company’s currently approved portfolio. If clearance for the products in the current portfolio were withdrawn by the FDA, this may have a material adverse impact on the Company. Disruption of our supply chain capabilities due to trade restrictions, political instability, severe weather, natural disasters, public health crises, terrorism, product recalls, labor supply or stoppages, the financial or operational instability of key suppliers and carriers, government restrictions or measures, or other reasons could impair our ability to distribute our products. The Company believes capacity issues and resource constraints and the related increased cost pressures and burdens on the hospital systems have had and may continue to have an adverse effect on its ability to generate sales due to the fluctuating and unpredictable levels of capacity medical providers have to perform procedures that require the use of its products. In addition, the Company has experienced disruptions in its manufacturing and supply chain, as well as delays in site initiation and patient enrollment for its clinical studies. If the Company is unable to successfully complete these or other clinical studies, its business and results of operations could be harmed. The Company is closely monitoring general economic conditions on global supply chain, manufacturing, and logistics operations. As inflationary pressures increase, the Company has experienced and further anticipates that its production and operating costs may continue to increase, including costs and availability of materials and labor. While the Company has sufficient inventory on-hand to meet its current production requirements and customer demand, it has experienced some constraints with respect to the availability of certain materials and extended lead times from certain key suppliers. The Company has also experienced some delays in shipping products to its customers. Any significant delay or interruption in our supply chain could impair the Company’s ability to meet the demands of its customers in the future and could harm its business. We use technology in substantially all aspects of our business operations, and our ability to serve customers most effectively depends on the reliability of our technology systems. Cybersecurity incidents can include computer viruses, computer denial-of-service attacks, worms, and other malicious software programs or other attacks, covert introduction of malware to computers and networks, impersonation of authorized users, and efforts to discover and exploit any design flaws, bugs, security vulnerabilities or security weaknesses, as well as intentional or unintentional acts by employees or other insiders with access privileges, intentional acts of vandalism by third parties and sabotage. In addition, our technology infrastructure and systems are vulnerable to damage or interruption from natural disasters, power loss and telecommunications failures. Any such disruption to our systems, or the technology systems of third parties on which we rely, the failure of these systems to otherwise perform as anticipated, or the theft, destruction, loss, misappropriation, or release of sensitive and/or confidential information or intellectual property, could require us to notify affected individuals, federal or state agencies or media outlets of the incident and could result in business disruption, negative publicity, loss of customers, potential liability, including litigation or other legal actions against us or the imposition of penalties, fines, fees or liabilities, which may not be covered by our insurance policies, and competitive disadvantage, any or all of which would potentially adversely affect our customer service, decrease the volume of our business and result in increased costs and lower profits. Moreover, a cybersecurity breach could require us to devote significant management resources to address the problems associated with the breach and to expend significant additional resources to upgrade further the security measures we employ to protect information against cyber-attacks and other wrongful attempts to access such information, which could result in a disruption of our operations. While we have invested, and continue to invest, in technology security initiatives and other measures to prevent security breaches and cyber incidents, as well as disaster recovery plans, these initiatives and measures may not be entirely effective to insulate us from technology disruption that could result in adverse effects on our results of operations.
Receivable [Policy Text Block]	Accounts Receivable Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The allowance for doubtful accounts is the Company’s best estimate of the amount of probable credit losses in the Company’s existing accounts receivable. The Company determines the allowance for doubtful accounts based upon an aging of accounts receivable, historical experience, and management judgment. Accounts receivable balances are reviewed individually for collectability. To date, the Company has not experienced significant credit-related losses. Accounts receivable allowance for doubtful accounts provision and recoveries or write-offs are summarized as follows (in thousands): 2023 2022 Beginning balance $ 73 $ 6 Provision 17 70 Recoveries/write-offs (49 ) (3 ) Ending balance $ 41 $ 73
Inventory, Policy [Policy Text Block]	Inventories Inventories are valued at the lower of cost or net realizable value. Cost is determined using the first-in, first-out method for all inventories. The Company’s policy is to write down inventory that has expired or become obsolete, inventory that has a cost basis in excess of its expected net realizable value, and inventory in excess of expected requirements. At each balance sheet date, management evaluates inventories for excess quantities, and obsolescence. This evaluation by management includes analysis of historical sales levels by product, projections of future demand, the risk of technological or competitive obsolescence for products, general market conditions, as well as the feasibility of reworking or using excess or obsolete products or components in the production or assembly of other products that are not obsolete or for which there are not excess quantities in inventory. To the extent that management determines there are excess or obsolete inventory, management adjusts the carrying value to estimated net realizable value. When quantities on hand exceed sales forecasts, a write-down is recorded for such excess inventories along with a corresponding charge to cost of revenues. The estimate of excess quantities is subjective and primarily dependent on the estimates of future demand for a particular product. Specifically, the future demand is derived based on our historical experience, from discussion with users of our products and general market conditions. Changes in assumptions of product demand could have a significant impact on the amount of write-down recorded. Inventory used in clinical trials is expensed at the time of production and recorded as research and development expense if the inventory is contractually being provided at no cost to the clinical site. The cost of inventories are regularly reviewed against estimated market value and record a lower of cost or market reserve for inventories that have a cost in excess of estimated market value, which could have a material impact on the gross margin and inventory balances based on additional write-downs to net realizable value or a benefit from inventories previously written down.
Property, Plant and Equipment, Policy [Policy Text Block]	Property and Equipment Property and equipment are recorded at cost. Repairs and maintenance costs are expensed as incurred. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the assets of generally three five
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]	Impairment of Long-Lived Assets The Company reviews long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. If indicators of impairment exist, an impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. Impairment, if any, is measured as the amount by which the carrying amount of the long-lived asset exceeds its fair value. The Company has not recorded any impairment of long-lived assets since inception through December 31, 2023.
Revenue [Policy Text Block]	Revenue Recognition The Company’s revenues are derived from (1) sale of Lightbox consoles, (2) sale of disposables, which consist of catheters and accessories, and (3) sale of customer service contracts and maintenance. The Company sells its products directly to hospitals and medical centers as well as through distributors. The Company accounts for a contract with a customer when there is a legally enforceable contract between the Company and the customer, the rights of the parties are identified, the contract has commercial substance, and collectability of the contract consideration is probable. The Company’s revenues are measured based on consideration specified in the contract with each customer, net of any sales incentives and taxes collected from customers that are remitted to government authorities. For all sales, the Company uses either a signed agreement, a binding purchase order or other written documentation as evidence of an arrangement. The Company’s revenue recognition policies generally result in revenue recognition at the following points: 1. Lightbox console sales: Provided all other criteria for revenue recognition have been met, the Company recognizes revenue for Lightbox console sales directly to end customers when delivery and acceptance occurs, which is defined as receipt by the Company of an executed form that the installation process is complete. If installation is not required, as is the case with the Lightbox 3, recognition occurs upon the completion of delivery pursuant to the stated delivery terms. 2. Sales of disposables: Disposable revenues consist of sales of the Company’s catheters and accessories and are recognized when the product has shipped, risk of loss and title has passed to the customer and collectability is reasonably assured. 3. Service revenue: Service contract revenue consists of preventative maintenance, upgrades, and service contracts. Service contracts are recognized ratably over the term of the service period and maintenance contract revenue is recognized when work is completed. To date, service revenue has been insignificant. The Company offers its customers the ability to purchase or lease the Lightbox console. In addition, the Company provides a Lightbox under a limited commercial evaluation program to allow accounts to install and utilize the Lightbox for a limited trial period. When a Lightbox is placed under a lease agreement or under a commercial evaluation program, the Company retains title to the equipment and it remains capitalized on its balance sheet under property and equipment. Depreciation expense on these placed Lightboxes is recorded to cost of revenues on a straight-line basis. The costs to maintain these placed Lightboxes are charged to cost of revenues as incurred. The Company evaluates its lease and commercial evaluation program agreements and accounts for these contracts under the guidance in Accounting Standards Codification (“ASC”) 842, Leases Revenue from Contracts with Customers (Topic 606) The Company assessed whether the embedded lease is an operating lease or sales-type lease. Based on the Company’s assessment of the guidance and given that any payments under the lease agreements are dependent upon contingent future sales, it was determined that collectability of the minimum lease payments is not reasonably predictable. Accordingly, the Company concluded the embedded lease did not meet the criteria of a sales-type lease and accounts for it as an operating lease. The Company recognizes revenue allocated to the lease as the contingent disposable product purchases are delivered and are included in revenues within the statement of operations and comprehensive loss. For sales of disposables through distributors, the Company recognizes revenue when control of the product transfers from the Company to the distributor. The distributors are responsible for all statutory obligations, marketing, sales, training and warranty in their respective territories. The standard terms and conditions contained in the Company’s distribution agreements do not provide price protection or stock rotation rights to any of its distributors. In addition, its distributor agreements do not allow the distributor to return or exchange products, and the distributor is obligated to pay the Company upon invoice regardless of its ability to resell the product.
Cost of Goods and Service [Policy Text Block]	Cost of Revenues Cost of revenues consists primarily of manufacturing overhead costs, material costs and direct labor. A significant portion of the Company’s cost of revenues currently consists of manufacturing overhead costs. These overhead costs include the cost of quality assurance, material procurement, inventory control, facilities, equipment and operations supervision and management. Cost of revenues also includes depreciation expense for the Lightboxes under lease, deployed with sales personnel and evaluation agreements, product warranty costs, product written-off due to excess or obsolescence, and certain direct costs such as shipping costs.
Standard Product Warranty, Policy [Policy Text Block]	Product Warranty Costs The Company typically offers a one 2023 2022 Beginning balance $ 109 $ 187 Warranty provision 107 22 Usage/Release (23 ) (100 ) Ending balance $ 193 $ 109
Research and Development Expense, Policy [Policy Text Block]	Research and Development The Company expenses research and development costs as incurred. Research and development expenses include personnel and personnel-related costs, costs associated with pre-clinical and clinical development activities, and costs for prototype products that are manufactured prior to market approval for that prototype product, and internal and external costs associated with the Company’s regulatory compliance, including the costs of outside consultants and contractors that assist in the process of submitting and maintaining regulatory filings, and overhead costs, including allocated facility and related expenses.
Clinical Trials [Policy Text Block]	Clinical Trials The Company accrues and expenses costs for its clinical trial activities performed by third parties, including clinical research organizations and other service providers, based upon estimates of the work completed over the life of the individual study in accordance with associated agreements. The Company determines these estimates through discussion with internal personnel and outside service providers as to progress or stage of completion of trials or services pursuant to contracts with clinical research organizations and other service providers and the agreed-upon fee to be paid for such services.
Share-Based Payment Arrangement [Policy Text Block]	Stock-Based Compensation Stock-based compensation for the Company includes amortization related to all stock options, restricted stock units (“RSU”), and restricted stock awards (“RSA”) based on the grant-date estimated fair value. The fair value of stock options is estimated on the date of grant using the Black-Scholes option pricing model and recognized as expense on a straight-line basis over the vesting period of the award. The Company has not granted any stock options since 2017. The Company measures the fair value of RSUs and RSAs using the closing stock price of a share of the Company’s common stock on the grant date and is recognized as expense on a straight-line basis over the vesting period of the award. As allowed under ASU No. 2016‑09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting
Foreign Currency Transactions and Translations Policy [Policy Text Block]	Foreign Currency The Company records net gains and losses resulting from foreign exchange transactions as a component of foreign currency exchange losses in other income (expense), net. During the years ended December 31, 2023 and 2022, the Company recorded a net gain of $12,000 and a net loss of $12,000 of foreign currency exchange, respectively.
Income Tax, Policy [Policy Text Block]	Income Taxes The Company utilizes the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and tax reporting bases of assets and liabilities and are measured using enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company’s policy is to record interest and penalties on uncertain tax positions as income tax expense when they occur. During the years ended December 31, 2023 and 2022, the Company did not
Earnings Per Share, Policy [Policy Text Block]	Net Loss per Share Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is computed by dividing the net loss applicable to common stockholders by the weighted average number of shares of common stock outstanding during the period, without consideration for potential dilutive common shares. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss applicable to common stockholders by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Any common stock shares subject to repurchase are excluded from the calculations as the continued vesting of such shares is contingent upon the holders’ continued service to the Company. As of December 31, 2023 and 2022, there were no Net loss per share applicable to common stockholders was determined as follows (in thousands, except per share data): Year Ended December 31, 2023 2022 Net loss applicable to common stockholders $ (18,320 ) $ (27,244 ) Weighted average common stock outstanding, basic and diluted 786 417 Net loss per share attributable to common stockholders, basic and diluted $ (23.31 ) $ (65.33 ) The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted average shares outstanding because such securities have an anti-dilutive impact due to losses reported: Year Ended December 31, 2023 2022 Common stock warrants equivalents 477,182 267,314 Common stock options 15 15 Convertible preferred stock 61,745 58,080 Unvested restricted stock units 123,547 365 662,489 325,774
Comprehensive Income, Policy [Policy Text Block]	Comprehensive Loss For the years ended December 31, 2023 and 2022, there was no difference between comprehensive loss and the Company’s net loss.
Segment Reporting, Policy [Policy Text Block]	Segment and Geographical Information The Company operates and manages its business as one
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Pronouncements Recent accounting standards not yet adopted In December 2023, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures In August 2020, the FASB issued ASU No. 2020-06, Debt Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging Contracts in Entity s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity s Own Equity

Note 2 - Summary of Significa_2

Note 2 - Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
Notes Tables
Accounts Receivable, Allowance for Credit Loss [Table Text Block]	2023 2022 Beginning balance $ 73 $ 6 Provision 17 70 Recoveries/write-offs (49 ) (3 ) Ending balance $ 41 $ 73
Schedule of Product Warranty Liability [Table Text Block]	2023 2022 Beginning balance $ 109 $ 187 Warranty provision 107 22 Usage/Release (23 ) (100 ) Ending balance $ 193 $ 109
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Year Ended December 31, 2023 2022 Net loss applicable to common stockholders $ (18,320 ) $ (27,244 ) Weighted average common stock outstanding, basic and diluted 786 417 Net loss per share attributable to common stockholders, basic and diluted $ (23.31 ) $ (65.33 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	Year Ended December 31, 2023 2022 Common stock warrants equivalents 477,182 267,314 Common stock options 15 15 Convertible preferred stock 61,745 58,080 Unvested restricted stock units 123,547 365 662,489 325,774

Note 4 - Inventories (Tables)

Note 4 - Inventories (Tables)	12 Months Ended
Note 4 - Inventories (Tables)	Dec. 31, 2023
Notes Tables
Schedule of Inventory, Current [Table Text Block]	December 31, 2023 2022 Raw materials $ 3,203 $ 3,374 Work-in-process 25 17 Finished products 2,070 1,574 Total inventories $ 5,298 $ 4,965

Note 5 - Property and Equipme_2

Note 5 - Property and Equipment, Net (Tables)	12 Months Ended
Note 5 - Property and Equipment, Net (Tables)	Dec. 31, 2023
Notes Tables
Property, Plant and Equipment [Table Text Block]	December 31, 2023 2022 Equipment held by customers and field sales personnel $ 2,495 $ 2,566 Machinery and equipment 1,379 1,372 Computer software 122 122 Computer equipment 200 200 Furniture and fixture 78 78 Leasehold improvements 320 320 Total property and equipment, gross 4,594 4,658 Less: Accumulated depreciation and amortization (4,107 ) (3,956 ) Total property and equipment, net $ 487 $ 702

Note 6 - Accrued Expenses and_2

Note 6 - Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2023
Notes Tables
Schedule of Accrued Liabilities [Table Text Block]	December 31, 2023 2022 Accrued product warranty costs $ 193 $ 109 Deferred revenue 172 141 Accrued professional fees 152 60 Accrued clinical trial costs 105 106 Accrued travel and entertainment expenses 88 129 Accrued sales and use tax 44 40 Other accrued liabilities 63 72 Total accrued expenses and other current liabilities $ 817 $ 657

Note 7 - Borrowings (Tables)

Note 7 - Borrowings (Tables)	12 Months Ended
Note 7 - Borrowings (Tables)	Dec. 31, 2023
Notes Tables
Schedule of Debt [Table Text Block]	Year Ending December 31, 2024 $ 7,827 2025 9,113 Total 16,940 Less: Amount of PIK additions and final facility fee to be incurred subsequent to December 31, 2023 (2,481 ) Less: Amount representing debt issuance costs (166 ) Borrowings, current portion, as of December 31, 2023 $ 14,293

Note 8 - Leases (Tables)

Note 8 - Leases (Tables)	12 Months Ended
Note 8 - Leases (Tables)	Dec. 31, 2023
Notes Tables
Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block]	Year Ending December 31, 2024 $ 1,138 Total 1,138 Less: Imputed interest (36 ) Leasehold liability as of December 31, 2023 $ 1,102
Right of Use Asset and Liabilities [Table Text Block]	December 31, Lease-Related Assets and Liabilities Financial Statement Line Items 2023 2022 Right of use assets: Operating lease Right of use asset $ 1,102 $ 2,194 Total right of use assets $ 1,102 $ 2,194 Lease liabilities: Operating lease Leasehold liability, current portion $ 1,102 $ 1,092 Leasehold liability, long-term portion — 1,102 Total lease liabilities $ 1,102 $ 2,194

Note 10 - Stockholders' Equity

Note 10 - Stockholders' Equity (Tables)	12 Months Ended
Note 10 - Stockholders' Equity (Tables)	Dec. 31, 2023
Notes Tables
Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]	Total Outstanding and Exercisable Underlying Shares of Common Stock Exercise Price per Share Expiration Date Series 1 Warrants issued in the February 2018 Series B financing 8,979,000 2,993 $ 6,000.00 February 2025 Series 2 Warrants issued in the February 2018 Series B financing 8,709,500 2,903 $ 6,000.00 February 2025 Placement agent warrants issued in the January 2022 financing 1,330,000 4,433 $ 150.00 January 2027 Warrants issued in the January 2022 financing 16,150,000 53,833 $ 144.00 July 2027 Series A Preferred Investment Options issued in August 2022 financing 2,853,883 190,259 $ 22.53 February 2028 Series B Preferred Investment Options issued in August 2022 financing 2,853,883 190,259 $ 22.53 August 2024 Placement agent Preferred Investment Options issued in the August 2022 financing 171,233 11,416 $ 32.85 August 2027 Total as of December 31, 2023 41,047,499 456,096 Total Outstanding and Exercisable Underlying Shares of Common Stock Exercise Price per Share Expiration Date Series 1 Warrants issued in the February 2018 Series B financing 8,979,000 2,993 $ 6,000.00 February 2025 Series 2 Warrants issued in the February 2018 Series B financing 8,709,500 2,903 $ 6,000.00 February 2025 Warrants issued in the November 2018 financing 8,768,395 2,923 $ 1,200.00 November 2023 Placement agent warrants issued in the January 2022 financing 1,330,000 4,433 $ 150.00 January 2027 Warrants issued in the January 2022 financing 16,150,000 53,833 $ 144.00 July 2027 Pre-funded warrants issued in the August 2022 financing 91,324 91,324 $ 0.0001 n/a Series A Preferred Investment Options issued in August 2022 financing 2,853,883 190,259 $ 22.53 February 2028 Series B Preferred Investment Options issued in August 2022 financing 2,853,883 190,259 $ 22.53 August 2024 Placement agent Preferred Investment Options issued in the August 2022 financing 171,233 11,416 $ 32.85 August 2027 Total as of December 31, 2022 49,907,218 550,343

Note 11 - Stock-based Compens_2

Note 11 - Stock-based Compensation (Tables)	12 Months Ended
Note 11 - Stock-based Compensation (Tables)	Dec. 31, 2023
Notes Tables
Share-Based Payment Arrangement, Option, Activity [Table Text Block]	Number of (in thousands) Weighted Average Price Weighted Average Remaining Contractual Life (in years) Intrinsic Value (in thousands) Balance at December 31, 2022 15 $ 183,340.00 4.02 $ — Balance at December 31, 2023 15 $ 183,340.00 3.29 $ — Exercisable at December 31, 2023 15 $ 183,340.00 3.29 $ — Vested and expected to vest at December 31, 2023 15 $ 183,340.00 3.29 $ —
Share-Based Payment Arrangement, Option, Exercise Price Range [Table Text Block]	Options Outstanding Options Vested Weighted Average Remaining Weighted Weighted Contractual Average Average Exercise Options Life (in Exercise Number Exercise Price Outstanding years) Price Exercisable Price $ 5,010.00 10 4.44 $ 5,010.00 10 $ 5,010.00 $ 540,000.00 5 1.00 $ 540,000.00 5 $ 540,000.00 15 3.29 $ 183,340.00 15 $ 183,340.00
Share-Based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block]	Number of Shares Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term (in years) Awards outstanding at December 31, 2021 668 $ 363.45 0.72 Released (572 ) $ 372.85 Forfeited (68 ) $ 362.12 Awards outstanding at December 31, 2022 28 $ 174.60 0.17 Awarded 100,189 $ 18.45 Released (2,294 ) $ 20.36 Forfeited (7,733 ) $ 18.45 Awards outstanding at December 31, 2023 90,190 $ 18.45 1.04
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]	Year Ended December 31, 2023 2022 Cost of revenues $ 134 $ 18 Research and development expenses 200 37 Selling, general and administrative expenses 606 72 $ 940 $ 127

Note 12 - Income Taxes (Tables)

Note 12 - Income Taxes (Tables)	12 Months Ended
Note 12 - Income Taxes (Tables)	Dec. 31, 2023
Notes Tables
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Year Ended December 31, 2023 2022 Tax at federal statutory rate $ (3,847 ) $ (3,701 ) State taxes, net of federal benefit 59 (916 ) Permanent differences 355 (484 ) Change in valuation allowance 3,382 5,084 Research credits (103 ) (273 ) Nondeductible interest expense 154 290 Other — — Provision for taxes $ — $ —
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	As of December 31, 2023 2022 Deferred tax assets: Federal, state and foreign net operating losses $ 87,568 $ 85,547 Research and other credits 5,546 5,343 Operating lease liability 275 544 Fixed assets 517 471 Accruals and other 3,842 3,628 Capitalized research and development 1,888 1,019 Total deferred tax assets 99,636 96,552 Less: Valuation allowance (99,358 ) (95,992 ) Total net deferred tax assets 278 560 Deferred liabilities: Property and equipment — — ) Operating lease right of use asset (278 ) (560 ) Total deferred tax liabilities (278 ) (560 ) Net deferred tax assets (liabilities) $ — $ —
Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]	As of December 31, 2023 2022 Balance at beginning of year $ 2,581 $ 2,366 Increase based on the tax positions in the current year 216 203 Increase (Decrease) for tax positions of prior year (118 ) 12 Balance at end of year $ 2,679 $ 2,581

Note 1 - Organization (Details

Note 1 - Organization (Details Textual) - USD ($)					1 Months Ended		12 Months Ended
Note 1 - Organization (Details Textual) - USD ($)	Mar. 05, 2024	Mar. 04, 2024	Aug. 04, 2022	Jan. 14, 2022	Aug. 31, 2022	Jan. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Nov. 04, 2022	May 20, 2022
Retained Earnings (Accumulated Deficit)							$ 420,696,000	$ 402,376,000
Cash and Cash Equivalents, at Carrying Value							$ 5,275,000	$ 14,603,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)							$ 0.001	$ 0.001
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)							456,096	550,343
Class of Warrant or Right, Outstanding (in shares)							41,047,499	49,907,218
Common Stock, Par or Stated Value Per Share (in dollars per share)							$ 0.001	$ 0.001
Common Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)				53,833
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)				$ 144
Warrants and Rights Outstanding, Term (Year)				5 years
Placement agent warrants issued in the January 2022 financing [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)				4,433			4,433	4,433
Class of Warrant or Right, Outstanding (in shares)							1,330,000	1,330,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)				$ 150			$ 150	$ 150
Warrants and Rights Outstanding, Term (Year)				5 years
Registered Direct Pre-funded Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)			52,268
Series A Preferred Investment Options [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)					190,259
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)					$ 22.53
Warrants and Rights Outstanding, Term (Year)					5 years 6 months
Series B Preferred Investment Options [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)					190,259
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)					$ 22.53
Warrants and Rights Outstanding, Term (Year)					2 years
Placement Agent Preferred Investment Options [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)					11,416
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)					$ 32.85
Warrants and Rights Outstanding, Term (Year)					5 years
Series D Preferred Stock [Member] \| Common Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)									53,833
Class of Warrant or Right, Outstanding (in shares)				53,833
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)				$ 144
Warrants and Rights Outstanding, Term (Year)				5 years
Series D Preferred Stock [Member] \| Placement agent warrants issued in the January 2022 financing [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)				4,433
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)				$ 150
August 2022 Public Offering [Member]
Proceeds from Issuance or Sale of Equity, Net					$ 4,400,000
The Market Offering Agreement (the “ATM Agreement”) [Member]
Proceeds from Issuance or Sale of Equity							$ 5,500,000
Proceeds from Issuance or Sale of Equity, Net							$ 6,500,000
Stock Issued During Period, Shares, New Issues (in shares)							607,241
Payments of Stock Issuance Costs							$ 164,000
Stock Issued During Period, Average Price Per Share (in dollars per share)							$ 9.01
January 2022 Public Offering [Member]
Proceeds from Issuance or Sale of Equity, Net						$ 6,700,000
January 2022 Public Offering [Member] \| Series D Preferred Stock [Member]
Stock Issued During Period, Shares, New Issues (in shares)				7,600
Preferred Stock, Par or Stated Value Per Share (in dollars per share)				$ 1,000
Preferred Stock, Convertible, Conversion Price (in dollars per share)				$ 120
August 2022 Purchase Agreement [Member]
Proceeds from Issuance or Sale of Equity			$ 4,400,000
Stock Issued During Period, Shares, New Issues (in shares)			46,667
Sale of Stock, Number of Shares (in shares)			98,935
Shares Issued, Price Per Share (in dollars per share)			$ 26.28
Private Placement [Member]
Stock Issued During Period, Shares, New Issues (in shares)			91,324
Shares Issued, Price Per Share (in dollars per share)			$ 26.28
Private Placement [Member] \| Registered Direct Pre-funded Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)			91,324
Common Stock in June, 2022 [Member]
Proceeds from Issuance or Sale of Equity								$ 1,000,000
Stock Issued During Period, Shares, New Issues (in shares)								39,048
Shares Issued, Price Per Share (in dollars per share)								$ 25.08
Common Stock, Par or Stated Value Per Share (in dollars per share)										$ 0.001
Share Offering Agreement, Aggregate Offering										$ 7,000,000
Commission Percentage										3%
Payments of Stock Issuance Costs								$ 29,000
Subsequent Event [Member]
Proceeds from Issuance or Sale of Equity		$ 7,500,000
Common Stock, Par or Stated Value Per Share (in dollars per share)		$ 0.001
Subsequent Event [Member] \| Securities Purchase Agreement [Member]
Proceeds from Issuance or Sale of Equity	$ 7,500,000

Note 2 - Summary of Significa_3

Note 2 - Summary of Significant Accounting Policies (Details Textual) shares in Thousands		12 Months Ended
	Mar. 11, 2022	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($)
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain (Loss), before Tax, Total		$ 0	$ 0
Warranty Period (Year)		1 year
Gain (Loss), Foreign Currency Transaction, before Tax		$ 12,000	12,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Total		$ 0	$ 0
Weighted Average Number of Shares, Common Stock Subject to Repurchase or Cancellation (in shares) \| shares		0
Number of Reportable Segments		1
Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)		3 years
Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)		5 years
Accounts Receivable [Member] \| Customer Concentration Risk [Member]
Number of Major Customers		1	0
Accounts Receivable [Member] \| Customer Concentration Risk [Member] \| One Customer [Member]
Concentration Risk, Percentage		24%
Revenue Benchmark [Member] \| Customer Concentration Risk [Member]
Number of Major Customers		1
Revenue Benchmark [Member] \| Customer Concentration Risk [Member] \| UNITED STATES
Concentration Risk, Percentage		90%	92%
Revenue Benchmark [Member] \| Customer Concentration Risk [Member] \| One Customer [Member]
Concentration Risk, Percentage		17%	14%
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	20

Note 2 - Summary of Significa_4

Note 2 - Summary of Significant Accounting Policies - Accounts Receivable, Allowance for Credit Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Beginning balance	$ 73	$ 6
Provision	17	70
Recoveries/write-offs	(49)	(3)
Ending balance	$ 41	$ 73

Note 2 - Summary of Significa_5

Note 2 - Summary of Significant Accounting Policies - Product Warranty (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Beginning balance	$ 109	$ 187
Warranty provision	107	22
Usage/Release	(23)	(100)
Ending balance	$ 193	$ 109

Note 2 - Summary of Significa_6

Note 2 - Summary of Significant Accounting Policies - Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Net loss applicable to common stockholders	$ (18,320)	$ (27,244)
Weighted average common stock outstanding, basic and diluted (in shares)	786	417
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (23.31)	$ (65.33)

Note 2 - Summary of Significa_7

Note 2 - Summary of Significant Accounting Policies - Anti-dilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Antidilutive securities (in shares)	662,489	325,774
Common Stock Warrants [Member]
Antidilutive securities (in shares)	477,182	267,314
Common Stock Options [ member]
Antidilutive securities (in shares)	15	15
Preferred Stock [Member]
Antidilutive securities (in shares)	61,745	58,080
Restricted Stock Units (RSUs) [Member]
Antidilutive securities (in shares)	123,547	365

Note 3 - Fair Value Measureme_2

Note 3 - Fair Value Measurements (Details Textual) $ in Thousands	Dec. 31, 2023 USD ($)
Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure, Total	$ 0
Liabilities, Fair Value Disclosure	0
Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure, Total	0
Liabilities, Fair Value Disclosure	$ 0

Note 4 - Inventories - Schedule

Note 4 - Inventories - Schedule of Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Raw materials	$ 3,203	$ 3,374
Work-in-process	25	17
Finished products	2,070	1,574
Total inventories	$ 5,298	$ 4,965

Note 5 - Property and Equipme_3

Note 5 - Property and Equipment, Net (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Depreciation	$ 289,000	$ 196,000
Property, Plant, and Equipment, Lessor Asset under Operating Lease, after Accumulated Depreciation	385,000	527,000
Leased Equipment [Member]
Cost, Depreciation	$ 208,000	$ 119,000

Note 5 - Property and Equipme_4

Note 5 - Property and Equipment, Net - Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property and Equipment	$ 4,594	$ 4,658
Less: Accumulated depreciation and amortization	(4,107)	(3,956)
Total property and equipment, net	487	702
Equipment Held by Customers [Member]
Property and Equipment	2,495	2,566
Machinery and Equipment [Member]
Property and Equipment	1,379	1,372
Software Development [Member]
Property and Equipment	122	122
Computer Equipment [Member]
Property and Equipment	200	200
Furniture and Fixtures [Member]
Property and Equipment	78	78
Leasehold Improvements [Member]
Property and Equipment	$ 320	$ 320

Note 6 - Accrued Expenses and_3

Note 6 - Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accrued product warranty costs	$ 193	$ 109
Deferred revenue	172	141
Accrued professional fees	152	60
Accrued clinical trial costs	105	106
Accrued travel and entertainment expenses	88	129
Accrued sales and use tax	44	40
Other accrued liabilities	63	72
Total accrued expenses and other current liabilities	$ 817	$ 657

Note 7 - Borrowings (Details Te

Note 7 - Borrowings (Details Textual)					12 Months Ended
Note 7 - Borrowings (Details Textual)	Aug. 02, 2023 USD ($) $ / shares shares	Aug. 10, 2022 USD ($)	Aug. 02, 2022 USD ($) $ / shares	Feb. 14, 2018 USD ($)	Dec. 31, 2023 USD ($) $ / shares	Dec. 31, 2022 USD ($) $ / shares	Dec. 31, 2021 USD ($)	Apr. 02, 2024 USD ($)	Jan. 26, 2024 USD ($)	Jun. 15, 2016 USD ($)	Sep. 22, 2015 USD ($)
Preferred Stock, Par or Stated Value Per Share (in dollars per share) \| $ / shares					$ 0.001	$ 0.001
Series E Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share (in dollars per share) \| $ / shares	$ 1,000		$ 1,000
Preferred Stock, Convertible, Conversion Ratio	93		93
Preferred Stock, Convertible, Conversion Price (in dollars per share) \| $ / shares	$ 10.725		$ 10.725
Preferred Stock, Convertible, Beneficial Ownership Percentage	1,999%		19.99%
Conversion of CRG Loan Into Series E Convertible Preferred Stock [Member]
Debt Conversion, Original Debt, Amount	$ 1,920,000		$ 1,920,000
Debt Conversion, Converted Instrument, Shares Issued (in shares) \| shares	1,920
CRG [Member] \| Loan Agreement [Member]
Debt Agreement, Maximum Borrowing Capacity											$ 50,000,000
Debt Instrument, Covenant Compliance, Minimum Liquidity Requirement				$ 3,500,000
Debt Instrument, Interest Rate, Stated Percentage		12.50%
Debt Instrument, Periodic Payment		$ 1,600,000
Long-Term Debt, Maturity, Year Four		6,500,000
Long-Term Debt, Maturity, Year Five		$ 6,500,000
Debt Instrument, Redemption Initial Prepayment Premium Percentage		5%
Debt Instrument, Redemption Annual Decline in Prepayment Premium Percentage		1%
Debt Instrument, Financing Fee Percentage		1.50%
Debt Instrument, Final Facility Fee Percentage		15%
Debt Instrument, Covenant Compliance Cash and Certain Cash Equivalents Minimum		$ 3,500,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net					$ 166,000	$ 249,000					1,300,000
Amortization of Debt Discount (Premium)					83,000		$ 83,000
Interest Expense, Debt					$ 2,000,000	$ 1,900,000
CRG [Member] \| Loan Agreement [Member] \| Forecast [Member]
Debt Instrument, Covenant Compliance, Minimum Liquidity Requirement								$ 3,500,000
CRG [Member] \| Loan Agreement [Member] \| Series A Preferred Stock Purchase Agreement with CRG [Member]
Debt Conversion, Original Debt, Amount				38,000,000
Debt Conversion, Fees and Prepayment Premium Amount				$ 3,800,000
CRG [Member] \| Loan Agreement [Member] \| First Tranche, Borrowed on September 22, 2015 [Member]
Debt Instrument, Face Amount											$ 30,000,000
CRG [Member] \| Loan Agreement [Member] \| Second Tranche, Borrowed on June 15, 2016 [Member]
Debt Instrument, Face Amount										$ 10,000,000
CRG [Member] \| Loan Agreement Amendment No. 7 [Member] \| Subsequent Event [Member]
Debt Instrument, Covenant Compliance, Minimum Liquidity Requirement									$ 1,000,000

Note 7 - Borrowings - Schedule

Note 7 - Borrowings - Schedule of Debt (Details) - CRG [Member] - Loan Agreement [Member] $ in Thousands	Dec. 31, 2023 USD ($)
2024	$ 7,827
2025	9,113
Total	16,940
Less: Amount of PIK additions and final facility fee to be incurred subsequent to December 31, 2023	(2,481)
Less: Amount representing debt issuance costs	(166)
SecuredDebt	$ 14,293

Note 8 - Leases (Details Textua

Note 8 - Leases (Details Textual) - USD ($)	12 Months Ended
Note 8 - Leases (Details Textual) - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Mar. 06, 2024	Apr. 01, 2019
Lessee, Operating Lease, Liability, to be Paid	$ 1,138,000			$ 5,800,000
Operating Lease, Weighted Average Remaining Lease Term	10 months 24 days
Lessee, Operating Lease, Discount Rate	6.50%
Operating Lease, Expense, Excluding Maintenance Fee and Other Expense, Monthly	$ 105,000
Operating Lease, Expense	1,300,000	$ 1,300,000
Variable Lease, Cost	400,000	300,000
Operating Lease, Right-of-Use Asset, Periodic Reduction	1,100,000	1,100,000
Prepaid Rent	$ 13,000	$ 65,000
Subsequent Event [Member]
Lessee, Operating Lease, Liability, to be Paid			$ 1,300,000

Note 8 - Leases - Future Operat

Note 8 - Leases - Future Operating Lease Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Apr. 01, 2019
2024	$ 1,138
Total	1,138		$ 5,800
Less: Imputed interest	(36)
Leasehold liability as of December 31, 2022	$ 1,102	$ 2,194

Note 8 - Leases - ROU Assets an

Note 8 - Leases - ROU Assets and Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Operating lease	$ 1,102	$ 2,194
Total right of use assets	1,102	2,194
Leasehold liability, current portion	1,102	1,092
Operating Lease, Liability, Noncurrent	0	1,102
Total lease liabilities	$ 1,102	$ 2,194

Note 9 - Commitments and Cont_2

Note 9 - Commitments and Contingencies (Details Textual) $ in Millions	Dec. 31, 2023 USD ($)
Purchase Commitment [Member]
Purchase Obligation	$ 0.5

Note 10 - Stockholders' Equit_2

Note 10 - Stockholders' Equity (Details Textual) $ / shares in Units, $ in Thousands					12 Months Ended
	Aug. 02, 2023 USD ($) $ / shares	Aug. 02, 2022 USD ($) $ / shares shares	Jan. 14, 2022 USD ($) $ / shares shares	Feb. 14, 2018	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Nov. 04, 2022 $ / shares shares	Aug. 31, 2022 $ / shares shares	Aug. 04, 2022 $ / shares shares
Preferred Stock, Shares Authorized					5,000,000	5,000,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share) \| $ / shares					$ 0.001	$ 0.001
Preferred Stock, Shares Issued					62,881	60,961
Preferred Stock, Shares Outstanding, Ending Balance (in shares)					62,881	60,961
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)					456,096	550,343
Preferred Stock Redemption Discount \| $					$ 0	$ 5,111
Common Stock, Shares Authorized					100,000,000	100,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share) \| $ / shares					$ 0.001	$ 0.001
Common Stock, Shares, Outstanding, Ending Balance (in shares)					1,279,928	522,177
Class of Warrant or Right, Outstanding (in shares)					41,047,499	49,907,218
Measurement Input, Expected Term [Member]
Warrants and Rights Outstanding, Measurement Input			5.5
Measurement Input, Price Volatility [Member]
Warrants and Rights Outstanding, Measurement Input			1.3661
Measurement Input, Risk Free Interest Rate [Member]
Warrants and Rights Outstanding, Measurement Input			0.0151
Measurement Input, Expected Dividend Rate [Member]
Warrants and Rights Outstanding, Measurement Input			0
Common Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)			53,833
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) \| $ / shares			$ 144
Warrants and Rights Outstanding, Term (Year)			5 years
Placement agent warrants issued in the January 2022 financing [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)			4,433		4,433	4,433
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) \| $ / shares			$ 150		$ 150	$ 150
Warrants and Rights Outstanding, Term (Year)			5 years
Class of Warrant or Right, Outstanding (in shares)					1,330,000	1,330,000
Registered Direct Pre-funded Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)									52,268
Stock Issued During Period, Shares, Warrants Exercised						52,268
Private Pre-funded Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)									91,324
Pre-funded Warrants Issued in August 2022 Financing [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)						91,324
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) \| $ / shares						$ 0.0001			$ 0.0001
Stock Issued During Period, Shares, Warrants Exercised					91,324
Class of Warrant or Right, Outstanding (in shares)					0	91,324
Series A Preferred Investment Options [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)								190,259
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) \| $ / shares								$ 22.53
Warrants and Rights Outstanding, Term (Year)								5 years 6 months
Series B Financing Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)								190,259
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) \| $ / shares								$ 22.53
Warrants and Rights Outstanding, Term (Year)								2 years
Placement Agent Preferred Investment Options [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)								11,416
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) \| $ / shares								$ 32.85
Warrants and Rights Outstanding, Term (Year)								5 years
November 2018 Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)						2,923
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) \| $ / shares						$ 1,200
Class of Warrant or Right, Outstanding (in shares)						8,768,395
Class of Warrant or Right Warrants Expired					8,768,395
January 2022 Public Offering [Member]
Proceeds from Issuance of Convertible Preferred Stock \| $			$ 4,000
August 2022 Public Offering [Member] \| Common Warrants [Member]
Conversion of Warrants Allowed Maximum Ownership of Common Stock Percentage upon Election									9.99%
Conversion of CRG Loan Into Series E Convertible Preferred Stock [Member]
Debt Conversion, Original Debt, Amount \| $	$ 1,920	$ 1,920
Series A Preferred Stock [Member]
Preferred Stock, Shares Outstanding, Ending Balance (in shares)					60,876	60,876
Preferred Stock, Liquidation Preference Per Share \| $ / shares					$ 1,000
Preferred Stock, Convertible, Conversion Price (in dollars per share) \| $ / shares					$ 6,000
Dividends, Preferred Stock \| $					$ 0	$ 4,500
Series A Preferred Stock [Member] \| CRG [Member]
Preferred Stock Dividends, Shares						4,510
Series A Preferred Stock [Member] \| Conversion of Principal Amount of Senior Secured Loan to Newly Authorized Series A Preferred Stock [Member]
Preferred Stock, Dividend Rate, Percentage				8%
Series B Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share (in dollars per share) \| $ / shares					$ 0.001
Preferred Stock, Shares Outstanding, Ending Balance (in shares)					85	85
Preferred Stock, Convertible, Conversion Price (in dollars per share) \| $ / shares					$ 5.732	$ 5.732
Series D Preferred Stock [Member]
Preferred Stock Redemption Discount \| $						$ 5,100
Series D Preferred Stock [Member] \| Common Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)							53,833
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) \| $ / shares			$ 144
Warrants and Rights Outstanding, Term (Year)			5 years
Class of Warrant or Right, Outstanding (in shares)			53,833
Series D Preferred Stock [Member] \| Placement agent warrants issued in the January 2022 financing [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)			4,433
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) \| $ / shares			$ 150
Series D Preferred Stock [Member] \| January 2022 offering [Member]
Preferred Stock, Par or Stated Value Per Share (in dollars per share) \| $ / shares			$ 0.001
Preferred Stock, Convertible, Conversion Price (in dollars per share) \| $ / shares							$ 120
Stock Issued During Period, Shares, New Issues (in shares)			7,600
Shares Issued, Price Per Share (in dollars per share) \| $ / shares			$ 1,000				$ 1,000
Preferred Stock, Convertible, Shares Issuable							63,333
Series D Preferred Stock [Member] \| January 2022 offering [Member] \| Common Warrants [Member]
Conversion of Warrants Allowed Maximum Ownership of Common Stock Percentage			4.99%
Series D Preferred Stock [Member] \| January 2022 Public Offering [Member]
Preferred Stock, Par or Stated Value Per Share (in dollars per share) \| $ / shares			$ 1,000
Preferred Stock, Convertible, Conversion Price (in dollars per share) \| $ / shares			$ 120
Stock Issued During Period, Shares, New Issues (in shares)			7,600
Conversion of Series D Preferred Stock into Common Stock [Member]
Conversion of Stock, Shares Converted						7,600
Conversion of Stock, Shares Issued						63,333
Common Stock Warrants, Issued with Series D Convertible Preferred Stock [Member]
Proceeds from Issuance of Warrants \| $			$ 3,600
Series E Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share (in dollars per share) \| $ / shares	$ 1,000	$ 1,000
Preferred Stock, Shares Outstanding, Ending Balance (in shares)					1,920
Preferred Stock, Dividend Rate, Percentage		8%
Preferred Stock, Convertible, Conversion Price (in dollars per share) \| $ / shares	$ 10.725	$ 10.725
Preferred Stock, Convertible, Shares Issuable		178,560
Preferred Stock, Convertible, Conversion Ratio	93	93
Preferred Stock, Convertible, Beneficial Ownership Percentage	1,999%	19.99%

Note 10 - Stockholders' Equit_3

Note 10 - Stockholders' Equity - Outstanding Warrants (Details) - $ / shares	Dec. 31, 2023	Dec. 31, 2022	Aug. 04, 2022	Jan. 14, 2022
Total outstanding and exercisable (in shares)	41,047,499	49,907,218
Total outstanding and exercisable (in shares)	41,047,499	49,907,218
Underlying shares of common stock (in shares)	456,096	550,343
Underlying shares of common stock (in shares)	456,096	550,343
Series 1 February 2018 Warrants [Member]
Total outstanding and exercisable (in shares)	8,979,000	8,979,000
Total outstanding and exercisable (in shares)	8,979,000	8,979,000
Underlying shares of common stock (in shares)	2,993	2,993
Underlying shares of common stock (in shares)	2,993	2,993
Exercise price per share (in dollars per share)	$ 6,000	$ 6,000
Exercise price per share (in dollars per share)	$ 6,000	$ 6,000
Series 2 February 2018 Warrants [Member]
Total outstanding and exercisable (in shares)	8,709,500	8,709,500
Total outstanding and exercisable (in shares)	8,709,500	8,709,500
Underlying shares of common stock (in shares)	2,903	2,903
Underlying shares of common stock (in shares)	2,903	2,903
Exercise price per share (in dollars per share)	$ 6,000	$ 6,000
Exercise price per share (in dollars per share)	$ 6,000	$ 6,000
November 2018 Warrants [Member]
Total outstanding and exercisable (in shares)		8,768,395
Total outstanding and exercisable (in shares)		8,768,395
Underlying shares of common stock (in shares)		2,923
Underlying shares of common stock (in shares)		2,923
Exercise price per share (in dollars per share)		$ 1,200
Exercise price per share (in dollars per share)		$ 1,200
Placement agent warrants issued in the January 2022 financing [Member]
Total outstanding and exercisable (in shares)	1,330,000	1,330,000
Total outstanding and exercisable (in shares)	1,330,000	1,330,000
Underlying shares of common stock (in shares)	4,433	4,433		4,433
Underlying shares of common stock (in shares)	4,433	4,433		4,433
Exercise price per share (in dollars per share)	$ 150	$ 150		$ 150
Exercise price per share (in dollars per share)	$ 150	$ 150		$ 150
Warrants Issued in the January 2022 Financing [Member]
Total outstanding and exercisable (in shares)	16,150,000	16,150,000
Total outstanding and exercisable (in shares)	16,150,000	16,150,000
Underlying shares of common stock (in shares)	53,833	53,833
Underlying shares of common stock (in shares)	53,833	53,833
Exercise price per share (in dollars per share)	$ 144	$ 144
Exercise price per share (in dollars per share)	$ 144	$ 144
Pre-funded Warrants Issued in August 2022 Financing [Member]
Total outstanding and exercisable (in shares)	0	91,324
Total outstanding and exercisable (in shares)	0	91,324
Underlying shares of common stock (in shares)		91,324
Underlying shares of common stock (in shares)		91,324
Exercise price per share (in dollars per share)		$ 0.0001	$ 0.0001
Exercise price per share (in dollars per share)		$ 0.0001	$ 0.0001
Series A Private Investment Options Issued in August 2022 Financing [Member]
Total outstanding and exercisable (in shares)	2,853,883	2,853,883
Total outstanding and exercisable (in shares)	2,853,883	2,853,883
Underlying shares of common stock (in shares)	190,259	190,259
Underlying shares of common stock (in shares)	190,259	190,259
Exercise price per share (in dollars per share)	$ 22.53	$ 22.53
Exercise price per share (in dollars per share)	$ 22.53	$ 22.53
Series B Private Investment Options Issued in August 2022 Financing [Member]
Total outstanding and exercisable (in shares)	2,853,883	2,853,883
Total outstanding and exercisable (in shares)	2,853,883	2,853,883
Underlying shares of common stock (in shares)	190,259	190,259
Underlying shares of common stock (in shares)	190,259	190,259
Exercise price per share (in dollars per share)	$ 22.53	$ 22.53
Exercise price per share (in dollars per share)	$ 22.53	$ 22.53
Placement Agent Private Investment Options Issued in August 2022 Financing [Member]
Total outstanding and exercisable (in shares)	171,233	171,233
Total outstanding and exercisable (in shares)	171,233	171,233
Underlying shares of common stock (in shares)	11,416	11,416
Underlying shares of common stock (in shares)	11,416	11,416
Exercise price per share (in dollars per share)	$ 32.85	$ 32.85
Exercise price per share (in dollars per share)	$ 32.85	$ 32.85

Note 11 - Stock-based Compens_3

Note 11 - Stock-based Compensation (Details Textual) - USD ($)		12 Months Ended
	Oct. 14, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 29, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period (in shares)		0	0
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)		0	0
Share Price				$ 2.71
Share-Based Payment Arrangement, Expense		$ 940,000	$ 127,000
Share-Based Payment Arrangement, Option [Member]
Share-Based Payment Arrangement, Expense, Tax Benefit		0	0
Restricted Stock Units (RSUs) [Member]
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount		$ 800,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition		1 year
Sharebased Compensation Arrangement by Sharebased Payment Award Equity Instruments Other than Options Nonvested Fair Value		$ 200,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value		42,000	14,000
Share-Based Payment Arrangement, Expense		$ 900,000	$ 100,000
Minimum [Member] \| Common Stock Options [ member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Purchase Price of Common Stock, Percent		110%
Minimum [Member] \| Restricted Stock Units (RSUs) [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)		2 years
The 2015 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Additional Shares Authorized	116,667
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant		300,000
The 2015 Employee Stock Purchase Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant		24,890

Note 11 - Stock-Based Compens_4

Note 11 - Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Options (in shares)	15	15
Options, weighted average exercise price (in dollars per share)	$ 183,340	$ 183,340
Options, weighted average remaining contractual life (Year)	3 years 3 months 14 days	4 years 7 days
Options, intrinsic value	$ 0	$ 0
Exercisable (in shares)	15
Exercisable, weighted average exercise price (in dollars per share)	$ 183,340
Exercisable, weighted average remaining contractual life (Year)	3 years 3 months 14 days
Exercisable, intrinsic value	$ 0
Vested and expected to vest (in shares)	15
Vested and expected to vest, weighted average exercise price (in dollars per share)	$ 183,340
Vested and expected to vest, weighted average remaining contractual life (Year)	3 years 3 months 14 days
Vested and expected to vest, intrinsic value	$ 0

Note 11 - Stock-Based Compens_5

Note 11 - Stock-Based Compensation - Options Outstanding and Vested (Details)	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Options Outstanding (in shares) \| shares	15
Weighted Average Remaining Contractual Life (Year)	3 years 3 months 14 days
Weighted Average Exercise Price (in dollars per share)	$ 183,340
Number Exercisable (in shares) \| shares	15
Weighted Average Exercise Price, options vested (in dollars per share)	$ 183,340
Exercise Price Range 1 [Member]
Exercise Price, Upper Limit (in dollars per share)	$ 5,010
Options Outstanding (in shares) \| shares	10
Weighted Average Remaining Contractual Life (Year)	4 years 5 months 8 days
Weighted Average Exercise Price (in dollars per share)	$ 5,010
Number Exercisable (in shares) \| shares	10
Weighted Average Exercise Price, options vested (in dollars per share)	$ 5,010
Exercise Price Range 2 [Member]
Exercise Price, Upper Limit (in dollars per share)	$ 540,000
Options Outstanding (in shares) \| shares	5
Weighted Average Remaining Contractual Life (Year)	1 year
Weighted Average Exercise Price (in dollars per share)	$ 540,000
Number Exercisable (in shares) \| shares	5
Weighted Average Exercise Price, options vested (in dollars per share)	$ 540,000

Note 11 - Stock-Based Compens_6

Note 11 - Stock-Based Compensation - Restricted Stock Units Award Activity (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Awards outstanding, shares (in shares)	28	668
Awards outstanding, Weighted Average Grant Date Fair Value (in dollars per share)	$ 174.6	$ 363.45
Awards outstanding, Weighted Average Remaining Contractual Term (Year)	1 year 14 days	2 months 1 day	8 months 19 days
Released, shares (in shares)	(2,294)	(572)
Released, Weighted Average Grant Date Fair Value (in dollars per share)	$ 20.36	$ 372.85
Forfeited, shares (in shares)	(7,733)	(68)
Forfeited, , Weighted Average Grant Date Fair Value (in dollars per share)	$ 18.45	$ 362.12
Awarded, shares (in shares)	100,189
Awarded, Weighted Average Grant Date Fair Value (in dollars per share)	$ 18.45
Awards outstanding, shares (in shares)	90,190	28	668
Awards outstanding, Weighted Average Grant Date Fair Value (in dollars per share)	$ 18.45	$ 174.6	$ 363.45

Note 11 - Stock-based Compens_7

Note 11 - Stock-based Compensation - Noncash Stock-based Compensation Expense Related to Stock Options, ESPP, and RSUs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Allocated Share-based Compensation Expense	$ 940	$ 127
Cost of Sales [Member]
Allocated Share-based Compensation Expense	134	18
Research and Development Expense [Member]
Allocated Share-based Compensation Expense	200	37
Selling, General and Administrative Expenses [Member]
Allocated Share-based Compensation Expense	$ 606	$ 72

Note 12 - Income Taxes (Details

Note 12 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Expense (Benefit)	$ 0	$ 0
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	3,400	5,100
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total		0	$ 0
State and Local Jurisdiction [Member]
Income Tax Expense (Benefit)	0	$ 0
Operating Loss Carryforwards	217,100
State and Local Jurisdiction [Member] \| Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	4,400
Domestic Tax Authority [Member]
Operating Loss Carryforwards	355,700
Operating Loss Carryforwards, Not Subject to Expiration	98,200
Domestic Tax Authority [Member] \| Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	$ 4,500

Note 12 - Income Taxes - Effect

Note 12 - Income Taxes - Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Tax at federal statutory rate	$ (3,847)	$ (3,701)
State taxes, net of federal benefit	59	(916)
Permanent differences	355	(484)
Change in valuation allowance	3,382	5,084
Research credits	(103)	(273)
Nondeductible interest expense	154	290
Other	0	0
Provision for taxes	$ 0	$ 0

Note 12 - Income Taxes - Deferr

Note 12 - Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Federal, state and foreign net operating losses	$ 87,568	$ 85,547
Research and other credits	5,546	5,343
Operating lease liability	275	544
Fixed assets	517	471
Accruals and other	3,842	3,628
Capitalized research and development	1,888	1,019
Total deferred tax assets	99,636	96,552
Less: Valuation allowance	(99,358)	(95,992)
Total net deferred tax assets	278	560
Property and equipment	0	0
Operating lease right of use asset	(278)	(560)
Total deferred tax liabilities	(278)	(560)
Net deferred tax assets (liabilities)	$ 0	$ 0

Note 12 - Income Taxes - Reconc

Note 12 - Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Balance at beginning of year	$ 2,581	$ 2,366
Increase based on the tax positions in the current year	216	203
Increase (Decrease) for tax positions of prior year	(118)
Increase (Decrease) for tax positions of prior year		12
Balance at end of year	$ 2,679	$ 2,581

Note 13 - 401(k) Plan (Details

Note 13 - 401(k) Plan (Details Textual) - Pension Plan [Member] - The 401(k) Plan [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	99%
Defined Contribution Plan, Cost	$ 0

Note 14 - Subsequent Events (De

Note 14 - Subsequent Events (Details Textual)				12 Months Ended
Note 14 - Subsequent Events (Details Textual)	Mar. 04, 2024 USD ($) $ / shares shares	Jan. 16, 2024 USD ($) $ / shares shares	Jan. 11, 2024 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Mar. 06, 2024 USD ($)	Dec. 29, 2023 $ / shares	Apr. 01, 2019 USD ($)
Share Price							$ 2.71
Share-Based Payment Arrangement, Expense \| $				$ 940,000	$ 127,000
Common Stock, Par or Stated Value Per Share (in dollars per share)				$ 0.001	$ 0.001
Preferred Stock, Par or Stated Value Per Share (in dollars per share)				$ 0.001	$ 0.001
Lessee, Operating Lease, Liability, to be Paid \| $				$ 1,138,000				$ 5,800,000
Common Stock [Member]
Stock Issued During Period, Shares, New Issues (in shares) \| shares				607,236	85,707
Subsequent Event [Member]
Share Price		$ 2.7	$ 2.93
Agreement to Purchase Common Stock, Maximum Amount \| $	$ 15,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.001
Proceeds from Issuance or Sale of Equity \| $	$ 7,500,000
Milestone Payment, Additional Authorized Amount \| $	$ 7,500,000
Lessee, Operating Lease, Term of Contract						1 year
Lessee, Operating Lease, Liability, to be Paid \| $						$ 1,300,000
Lessee, Operating Lease, Renewal Term						1 year
Subsequent Event [Member] \| Series F Preferred Stock [Member]
Stock Issued During Period, Shares, New Issues (in shares) \| shares	7,224
Shares Issued, Price Per Share (in dollars per share)	$ 1,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	0.001
Preferred Stock, Stated Value (in dollars per share)	$ 1,000
Preferred Stock, Convertible, Conversion Ratio	273
Subsequent Event [Member] \| Series G Preferred Stock [Member]
Preferred Stock, Stated Value (in dollars per share)	$ 1,000
Preferred Stock, Par Value	0.001
Subsequent Event [Member] \| Series G Preferred Stock [Member] \| Minimum [Member]
Preferred Stock, Convertible, Conversion Price (in dollars per share)	$ 0.2
Subsequent Event [Member] \| Series A-1 Preferred Stock [Member]
Securities Purchase Agreement, Number of Shares to Convert \| shares	10,000
Preferred Stock, Convertible, Shares Issuable \| shares	2,729,257
Subsequent Event [Member] \| Common Stock [Member]
Stock Issued During Period, Shares, New Issues (in shares) \| shares	75,327
Shares Issued, Price Per Share (in dollars per share)	$ 3.664
Subsequent Event [Member] \| License and Distribution Agreement [Member]
License Agreement, Term	20 years
Restricted Stock Units (RSUs) [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period \| shares				100,189
Share-Based Payment Arrangement, Expense \| $				$ 900,000	$ 100,000
Restricted Stock Units (RSUs) [Member] \| Minimum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)				2 years
Restricted Stock Units (RSUs) [Member] \| Subsequent Event [Member] \| Share-Based Payment Arrangement, Nonemployee [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period \| shares			76,791
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Grant Date Fair Value \| $			$ 75,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)			1 year
Restricted Stock [Member] \| Subsequent Event [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period \| shares		317,314
Share-Based Payment Arrangement, Expense \| $		$ 900,000
Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares) \| shares		123,285
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Net \| shares		194,029