Equity Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2021

Equity Incentive Plans

Schedule of stock-based compensation expense

	Year Ended
	December 31,
	2021		2020		2019
Cost of goods sold	$	271	$	14	$	—
Research and development		490		651		522
Selling and marketing		148		108		—
General and administrative		2,429		2,045		1,240
Total	$	3,338	$	2,818	$	1,762

Schedule of assumptions used to compute employee stock-based compensation

	2021		2020		2019
Risk‑free interest rate	.66% - 1.51	%	.40% - 1.68	%	1.74% ‑ 2.61	%
Expective volatility	105% ‑ 106	%	65% ‑ 106	%	65	%
Expected dividend yield	0	%	0	%	0	%
Expected life (in years)	6.25		6.25		6.25

Summary of options outstanding, vested and exercisable

			Weighted
		Weighted	Average
		Average	Remaining
		Exercise	Contractual	Aggregate
	Options	Price	Life (Years)	Intrinsic Value
Options outstanding at December 31, 2019	7,192,357	3.42	7.2
Options granted	2,539,403	2.80
Options exercised	(503,448)	1.21
Options cancelled/forfeited	(709,226)	6.20
Options outstanding at December 31, 2020	8,519,086	3.13	7.3
Options granted	2,581,647	2.63
Options exercised	(126,400)	0.60
Options cancelled/forfeited	(606,891)	6.61
Options outstanding at December 31, 2021	10,367,442	2.83	7.1	$	—
Options exercisable at December 31, 2021	6,262,675	2.99	6.0	$	—
Vested and expected to vest at December 31, 2021	10,367,442			$	—

Schedule of restricted stock activity

		Weighted Average	Aggregate
	Shares	Grant Date Fair Value	Intrinsic Value
Restricted stock units outstanding at December 31, 2019	—
Granted	159,795	2.81
Restricted stock units outstanding at December 31, 2020	159,795	—	$	458
Granted	297,576	1.68
Vested	(124,081)	2.81
Restricted stock units outstanding at December 31, 2021	333,290	1.80	$	163