Note 5 - Share-based Compensation - Noncash Stock Option Compensation (Details) - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Stock-based compensation	$ 334,316	$ 454,500	$ 664,955	$ 908,291
Share-Based Payment Arrangement, Option [Member]
Stock-based compensation	278,373	454,500	554,914	908,291
Restricted Stock Units (RSUs) [Member]
Stock-based compensation	55,943	0	110,041	0
General and Administrative Expense [Member]
Stock-based compensation	323,796	389,885	643,132	778,548
Research and Development Expense [Member]
Stock-based compensation	$ 10,520	$ 64,615	$ 21,823	$ 129,743