Note 2 - Liquidity and Uncertainties (Details Textual) - USD ($)	1 Months Ended		3 Months Ended		9 Months Ended
	Jun. 30, 2020	Apr. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Retained Earnings (Accumulated Deficit), Ending Balance			$ (106,582,501)		$ (106,582,501)		$ (100,885,957)
Net Income (Loss) Attributable to Parent, Total			(2,043,207)	$ (1,490,989)	(5,696,544)	$ (6,257,668)
Proceeds from Issuance of Common Stock					0	18,043,284
Cash and Cash Equivalents, at Carrying Value, Ending Balance			$ 14,490,745		14,490,745		$ 14,223,917
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total					$ 266,828	$ 12,932,631
April 6, 2020 Public Offering [Member]
Proceeds from Issuance of Common Stock		$ 4,600,000
June 30, 2020 Public Offering [Member]
Proceeds from Issuance of Common Stock	$ 13,400,000