Equity Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2023

Equity Incentive Plans

Schedule of stock-based compensation expense

	Year Ended
	December 31,
	2023		2022		2021
Cost of product revenues	$	107	$	133	$	271
Research and development		358		372		490
Selling and marketing		102		155		148
General and administrative		1,414		1,832		2,429
Total	$	1,981	$	2,492	$	3,338

Schedule of assumptions used to compute employee stock-based compensation

	2023		2022		2021
Risk‑free interest rate	3.87%-3.90	%	1.71% - 4.22	%	.66% - 1.51	%
Expected volatility	115.9%-118.6	%	107% ‑ 118	%	105% ‑ 106	%
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, 2021	5,183	5,666.50	6.1
Options granted	3,749	198.50
Options exercised	—	—
Options cancelled/forfeited	(1,004)	4,872.00
Options outstanding at December 31, 2022	7,928	3,187.50	7.7
Options granted	35,825	2.64
Options exercised	—	—
Options cancelled/forfeited	(710)	2,398.42
Options outstanding at December 31, 2023	43,043	548.70	9.0	$	—
Options exercisable at December 31, 2023	5,007	4,438.73	5.8	$	—
Vested and expected to vest at December 31, 2023	43,043			$	—

Schedule of restricted stock activity

		Weighted Average	Aggregate
	Shares	Grant Date Fair Value	Intrinsic Value
Restricted stock units outstanding at December 31, 2021	167		$	163
Granted	94	52.50
Vested	(135)	3,815.00
Restricted stock units outstanding at December 31, 2022	125	—	$	163
Granted	155,004	2.46
Vested	(112)	674.63
Forfeited	(1,500)	2.48
Restricted stock units outstanding at December 31, 2023	153,517		$	299