Balance Sheet Details - Schedule of Fixed Assets and Accrued Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Inventories
Raw materials	$ 2,735	$ 2,303
Subassemblies	414	294
Finished goods	72	54
Inventory, Gross	3,221	2,651
Fixed Assets
Machinery and equipment	3,079	3,063
Furniture and office equipment	161	161
Computer equipment and software	2,931	2,931
Leasehold improvements	634	634
Construction in process	387	245
Total fixed assets, gross	7,192	7,034
Less: accumulated depreciation and amortization	(4,812)	(4,633)
Total fixed assets, net	2,380	2,401
Accrued Liabilities
Accrued payroll	992	725
Accrued vacation	818	961
Accrued bonuses	493	178
Accrued sales commissions	1,813	600
Accrued other	434	554
Total accrued liabilities	$ 4,550	$ 3,018