Note 7 - Financial Instruments	9 Months Ended
Sep. 30, 2022
Notes to Financial Statements
Financial Instruments Disclosure [Text Block]	7. Financial Instruments 2016 Warrant On September 2, 2016, the Company entered into a loan and security agreement (as amended from time to time, the “Loan Agreement”) with OCM Strategic Credit SIGTEC Holdings, LLC (“Lender”). The Company voluntarily prepaid this Loan Agreement in 2020. Upon such prepayment and release, the Loan Agreement was terminated. In connection with the entry into the Loan Agreement, the Company issued a warrant (the “Warrant”) to the Lender on September 2, 2016 to purchase a number of shares of the Company’s common stock equal to $4.0 million divided by the lower of (i) $2.29 per share and (ii) the subscription price paid in connection with the Rights Offering. The Warrant provides for weighted average anti-dilution protection and is exercisable in whole or in part for ten (10) years from the date of issuance. The per share subscription price paid was $1.50 in connection with the Rights Offering; accordingly, the exercise price of the Warrant was set at $1.50 per share, and there were 2.7 million shares underlying the Warrant. Taking into account partial exercises of the Warrant, there were approximately 1.0 million shares underlying the outstanding Warrant as of December 31, 2021. In the second quarter of 2022, the Warrant was fully exercised, and therefore there are no remaining underlying shares as of September 30, 2022. See Note 8. For the nine months ended September 30, 2022, we recorded a gain of approximately $0.4 million, reflecting a decrease in the fair value of the liability-classified warrant primarily due to the decrease in our stock price prior to the exercise of the Warrant. As of December 31, 2021, there were approximately 1.0 million shares underlying the outstanding Warrant and the fair value of the Warrant was $6.5 million. The fair value of the liability-classified Warrant was calculated using the following assumptions: risk-free interest rate of 1.21%; no dividend yield; an expected life of 4.7 years; and a volatility factor of 55%.

Note 7 - Financial Instruments

9 Months Ended

Sep. 30, 2022

Financial Instruments Disclosure [Text Block]

2016 Warrant

On September 2, 2016, the Company entered into a loan and security agreement (as amended from time to time, the “Loan Agreement”) with OCM Strategic Credit SIGTEC Holdings, LLC (“Lender”). The Company voluntarily prepaid this Loan Agreement in 2020. Upon such prepayment and release, the Loan Agreement was terminated. In connection with the entry into the Loan Agreement, the Company issued a warrant (the “Warrant”) to the Lender on September 2, 2016 to purchase a number of shares of the Company’s common stock equal to $4.0 million divided by the lower of (i) $2.29 per share and (ii) the subscription price paid in connection with the Rights Offering. The Warrant provides for weighted average anti-dilution protection and is exercisable in whole or in part for ten (10) years from the date of issuance. The per share subscription price paid was $1.50 in connection with the Rights Offering; accordingly, the exercise price of the Warrant was set at $1.50 per share, and there were 2.7 million shares underlying the Warrant. Taking into account partial exercises of the Warrant, there were approximately 1.0 million shares underlying the outstanding Warrant as of December 31, 2021.

In the second quarter of 2022, the Warrant was fully exercised, and therefore there are no remaining underlying shares as of September 30, 2022. See Note 8. For the nine months ended September 30, 2022, we recorded a gain of approximately $0.4 million, reflecting a decrease in the fair value of the liability-classified warrant primarily due to the decrease in our stock price prior to the exercise of the Warrant.

As of December 31, 2021, there were approximately 1.0 million shares underlying the outstanding Warrant and the fair value of the Warrant was $6.5 million. The fair value of the liability-classified Warrant was calculated using the following assumptions: risk-free interest rate of 1.21%; no dividend yield; an expected life of 4.7 years; and a volatility factor of 55%.