Note 15 - Stock Based Compensation (Tables)

3 Months Ended

Mar. 31, 2023

Notes Tables

Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Three Months Ended March 31,
	2023		2022
Risk-free interest rate		3.87% - 4.25%		1.86% - 2.53%
Expected term (in years)		5.50 - 6.11		5.51 - 6.11
Dividend yield		-		-
Expected volatility		103% - 118%		117% - 128%

Share-Based Payment Arrangement, Option, Activity [Table Text Block]

	Number of Underlying Shares			Weighted-Average Exercise Price Per Share		Weighted-Average Contractual Life Remaining in Years		Aggregate Intrinsic Value
Outstanding as of January 1, 2023		13,906		$	2.35				-
Granted		2,461		$	0.72
Exercised		-			-
Forfeited		-			-
Expired		(3	)	$	793.83
Outstanding as of March 31, 2023		16,364		$	1.95		7.93	$	44
Exercisable as of March 31, 2023		11,227		$	2.32		7.28
Vested and expected to vest		11,227		$	1.95		7.93	$	44

Share-Based Payment Arrangement, Option [Member]

Notes Tables

Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	Three Months Ended March 31,
	2023		2022
General and administrative	$	1,054	$	1,184
Research and development		519		622
Total stock-based compensation expense	$	1,573	$	1,806