Income Taxes - Deferred tax assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets
Net operating loss carryforwards	$ 61,427	$ 55,091
Interest expense carryforward	523
Research and development credits	830	623
Lease liability	557	387
Capitalized research and development expenses	4,845	1,743
Accrued expenses and other	3,535	2,682
Inventory reserve	289	372
Gross deferred tax asset	72,006	60,898
Deferred tax liabilities
Depreciation and amortization	(436)	(435)
Right of use asset	(484)	(302)
Gross deferred tax liability	(920)	(737)
Net deferred tax asset before valuation allowance	71,086	60,161
Valuation allowance	(71,086)	(60,161)
Net deferred tax asset	$ 0	$ 0