Note 4 - Long-lived Assets - Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Total property and equipment, gross	$ 1,323	$ 1,674
Less: Accumulated depreciation and amortization	(465)	(448)
Total property and equipment, net	$ 858	1,226
Computer Equipment [Member]
Total property and equipment, useful lives (Year)	4 years
Total property and equipment, gross	$ 0	42
Lab Equipment [Member]
Total property and equipment, useful lives (Year)	5 years
Total property and equipment, gross	$ 8	17
Office Equipment, Furniture and Fixtures [Member]
Total property and equipment, useful lives (Year)	5 years
Total property and equipment, gross	$ 88	106
Leasehold Improvements [Member]
Total property and equipment, gross	$ 185	185
Machinery and Equipment [Member]
Total property and equipment, useful lives (Year)	7 years
Total property and equipment, gross	$ 1,042	$ 1,324