Note 14 - Income Taxes - Effective Income Tax Reconciliation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Tax at federal statutory rate	$ (3,151,000)	$ (3,089,000)
State, net of federal benefit	(449,000)	(414,000)
Research and development credit	(276,000)	(225,000)
Share-based compensation	649,000	446,000
PPP Note forgiveness	(107,000)
Other	2,000	5,000
Change in valuation allowance	3,332,000	3,277,000
Total provision for income taxes	$ 0	$ 0