Balance Sheet Components - Property and Equipment (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Land, Property and Equipment
Total property and equipment at cost	$ 961,000		$ 961,000
Accumulated depreciation	(477,000)		(465,000)
Property and equipment, net	484,000		496,000
Depreciation and amortization expense	12,000	$ 16,000
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	477,000		477,000
Software
Land, Property and Equipment
Total property and equipment at cost	63,000		63,000
Furniture and fixtures
Land, Property and Equipment
Total property and equipment at cost	18,000		18,000
Computers and peripherals
Land, Property and Equipment
Total property and equipment at cost	$ 7,000		$ 7,000