Note 8 - Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
U.S. Federal tax benefit at statutory rates, amount	$ (471)	$ (397)
U.S. Federal tax benefit at statutory rates, percent	21.00%	21.00%
Tax credits, amount	$ 0	$ 109
Tax credits, percent	0.00%	(5.80%)
State income tax, amount	$ (83)	$ (53)
State income tax, percent	3.70%	2.80%
International operations, amount	$ 28	$ (6)
International operations, percent	(1.30%)	0.30%
Stock-based compensation, amount	$ 93	$ 317
Stock-based compensation, percent	(4.20%)	(16.80%)
Valuation allowance, amount	$ 429	$ (1,224)
Valuation allowance, percent	(19.10%)	64.80%
Expiration of tax attributes, amount	$ 311	$ 1,330
Expiration of tax attributes, percent	(13.90%)	(70.40%)
PPP loan forgiveness, amount	$ (333)	$ 0
PPP loan forgiveness, percent	14.90%	0.00%
Other, net, amount	$ 26	$ (76)
Other, net, percent	(1.10%)	4.00%
Tax expense and effective tax rate, amount	$ (0)	$ (0)
Tax expense and effective tax rate, percent	0.00%	0.00%