Balance Sheet Components - Property and Equipment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Land, Property and Equipment
Total property and equipment at cost	$ 948,000	$ 942,000
Accumulated depreciation	(298,000)	(265,000)
Property and equipment, net	650,000	677,000
Depreciation and amortization expense	33,000	40,000
Land
Land, Property and Equipment
Total property and equipment at cost	396,000	396,000
Lab equipment
Land, Property and Equipment
Total property and equipment at cost	424,000	418,000
Clinical equipment
Land, Property and Equipment
Total property and equipment at cost	65,000	65,000
Software
Land, Property and Equipment
Total property and equipment at cost	$ 63,000	$ 63,000