Note 2 - Significant Accounting Policies 1 (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Retained Earnings (Accumulated Deficit), Ending Balance	$ (128,697,000)	$ (116,074,000)
Cash and Cash Equivalents, at Carrying Value, Ending Balance	12,872,000	21,407,000
Accounts Receivable, Allowance for Credit Loss, Current	22,000	16,000
Impairment of Long-Lived Assets Held-for-use	$ 0
Standard Product Warranty, Term (Year)	2 years
Standard Product Warranty Accrual, Ending Balance	$ 0	$ 0