Note 11 - Share-based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Notes Tables

Schedule of Share-based Compensation, Expense [Table Text Block]

	Years ended December 31,
	2020		2019
Cost of goods sold	$	-	$	191
Research and development		1,369		1,115
Selling, general and administrative		1,583		1,416
Total stock-based compensation	$	2,952	$	2,722

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

	Options outstanding
	Number of shares			Weighted average exercise price		Weighted average remaining contractual term (years)		Aggregate intrinsic value (in thousands)
Balance, December 31, 2019		821,464		$	18.99		7.6	$	-
Stock options granted		342,232			3.10
Stock options exercised		—			—
Stock options cancelled		(49,390	)		12.79
Balance, December 31, 2020		1,114,306		$	5.89		7.5	$	177.1
Options exercisable December 31, 2020		615,470		$	7.51		6.3	$	15.6
Options vested and expected to vest		1,114,306		$	5.89		7.5	$	177.1

Schedule of Nonvested Restricted Stock Units Activity [Table Text Block]

				Weighted
				average
				grant date
	Number of			fair values
	shares			per share
Balance, December 31, 2019		36,981		$	10.56
RSUs granted		381,094			3.93
RSUs vested and settled		(137,603	)		5.48
RSUs forfeited		(56,161	)		3.75
Balance, December 31, 2020		224,311		$	4.12

Share-based Payment Arrangement, Option [Member]

Notes Tables

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

	Years ended December 31,
	2020				2019
Risk-free interest rate		0.4	-	1.6%		1.40	-	2.14%
Volatility		107	-	112%		74	-	94%
Dividend yield		None				None
Expected term (in years)		6.25	-	10.0		6.25	-	10.0