Note 10 - Share-based Compensation (Tables)

9 Months Ended

Sep. 30, 2020

Notes Tables

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

	Three months ended September 30,				Nine months ended September 30,
	2020		2019		2020		2019
Cost of goods sold	$	-	$	38	$	-	$	130
Research and development		357		293		1,088		788
Selling, general and administrative		380		425		1,245		1,224
Total stock-based compensation	$	737	$	756	$	2,333	$	2,142

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

	Options outstanding
	Number of shares			Weighted average exercise price		Weighted average remaining contractual term (years)
Balance, December 31, 2019		821,464		$	18.99		6.6
Stock options granted		300,432			3.15
Stock options exercised		—			-
Stock options canceled		(43,083	)		13.19
Balance, September 30, 2020		1,078,813		$	6.04		7.6
Exercisable and vested, September 30, 2020		574,574		$	7.77		6.4

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

	Number of shares		Weighted average grant date fair value per share
Balance, December 31, 2019		36,981	$	10.56
RSUs granted		338,418		3.99
RSUs vested		97,796		5.99
RSUs forefeited		56,161		3.75
Balance, September 30, 2020		221,442	$	4.26