Balance Sheet Components - Property and Equipment, net (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Property and Equipment, net
Total property and equipment	$ 2,942,000	$ 2,413,000
Less: Accumulated depreciation	(1,585,000)	(1,155,000)
Property and equipment, net	1,357,000	1,258,000
Depreciation expense	430,000	332,000
Lab equipment
Property and Equipment, net
Total property and equipment	2,390,000	2,200,000
Computer equipment and software
Property and Equipment, net
Total property and equipment	25,000	25,000
Construction in progress
Property and Equipment, net
Total property and equipment		$ 188,000
Leasehold improvements
Property and Equipment, net
Total property and equipment	$ 527,000