Note 7 - Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($)	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Stock-based compensation expense	$ 897,260	$ 736,119
Research and Development Expense [Member]
Stock-based compensation expense	154,041	164,791
General and Administrative Expense [Member]
Stock-based compensation expense	$ 743,219	$ 571,328

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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