Income Taxes - Deferred tax assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023
Deferred tax assets:
Net operating loss carryforwards	$ 27,110	$ 22,068
Inventory	273	287
Accruals	737	863
Depreciation and amortization	27	13
Research and experimental expenditures	2,229	4,728
Stock-based compensation	270	268
Right of use liability	1,477	1,245
Gross deferred tax assets	32,123	29,472
Valuation allowance	(30,328)	(27,748)
Deferred tax assets	1,795	1,724
Deferred tax liabilities:
Right of use asset	(1,463)	(1,226)
Other	(332)	(348)
Deferred tax liabilities	(1,795)	(1,574)
Net deferred tax assets		$ 150
(Decrease) increase in valuation allowance	$ (2,600)