Note 4 - Property and Equipment, Net - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property and equipment, gross	$ 719	$ 1,170
Less accumulated depreciation	(537)	(1,025)
Property and equipment, net	182	145
Computer Equipment and Software [Member]
Property and equipment, gross	133	159
Laboratory and Manufacturing Equipment [Member]
Property and equipment, gross	460	550
Furniture and Fixtures [Member]
Property and equipment, gross	26	59
Leasehold Improvements [Member]
Property and equipment, gross	26	332
Construction in Progress [Member]
Property and equipment, gross	$ 74	$ 70

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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