Income Taxes - Deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred taxes, net
Net operating loss carryforward	$ 469	$ 324
Accruals	22	22
Reserves	9	11
Property, plant and equipment, and intangible assets	48	28
Stock-based compensation expense	85	132
Other	4	10
Total deferred tax assets	637	527
Valuation allowance	629
Net deferred tax assets	$ 8	$ 527