Note 13 - Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets
Net operating loss carryforwards and credits	$ 25,742	$ 20,698
Employee compensation	570	0
Share-based compensation expense	2,053	3,813
Property, plant and equipment	753	725
Common stock warrant liabilities	83	0
Operating lease liabilities	125	91
Other	55	54
Less: valuation allowance	(26,461)	(22,669)
Total deferred tax assets	2,920	2,712
Deferred tax liabilities
Common stock warrant liabilities	0	(1,129)
Operating lease Right-of-use assets	(2,920)	(1,583)
Total deferred tax liabilities	(2,920)	(2,712)
Net deferred tax assets (liabilities)	$ 0	$ 0