Note 12 - Equity Incentive Plan (Tables)

6 Months Ended

Jun. 30, 2022

Notes Tables

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

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Cost of product revenue	$	227	$	214	$	403	$	343
Research & development		503		402		870		643
Selling, general & administrative		3,351		2,181		5,323		4,070
Total stock-based compensation expense	$	4,081	$	2,797	$	6,626	$	5,056

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

	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2021		1,175,993		$	39.56
Granted		464,775		$	23.21
Exercised		(437	)	$	9.10			$	10
Forfeited and canceled		(130,925	)	$	44.25
Outstanding as of June 30, 2022		1,509,406		$	35.53		8.5	$	21
Vested, June 30, 2022		459,732		$	40.07		7.5	$	7
Vested or expected to vest, June 30, 2022		1,509,406		$	35.53		8.5	$	21

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

	Six Months Ended June 30,
	2022				2021
Risk free interest rate		1.3%	-	3.0%		0.3%	-	0.6%
Expected volatility		53.8%	-	55.2%		54.8%	-	55.9%
Expected life (years)			4.5				4.0
Expected dividend yield			0.0%				0.0%
Fair value per option			11.28				14.19

Share-Based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]

	Number of Shares			Weighted Average Fair Value
Outstanding as of December 31, 2021		412,658		$	36.33
Granted		498,189		$	25.18
Vested		(149,365	)	$	36.26
Forfeited and cancelled		(41,095	)	$	33.75
Outstanding as of June 30, 2022		720,387		$	28.78

Schedule of Nonvested Performance-Based Units Activity [Table Text Block]

	Number of Shares			Weighted Average Fair Value
Outstanding as of December 31, 2021		158,297		$	37.44
Performance factor adjustment		2,125		$	32.53
Vested		(19,125	)	$	32.53
Forfeited and cancelled		(23,400	)	$	41.86
Outstanding as of June 30, 2022		117,897		$	34.98