Note 3 - Summary of Significant Accounting Policies - Potentially Dilutive Securities (Details) - shares	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Stock Options (in shares)	4,198,006	3,072,297
Warrants (in shares)	6,596,096	7,557,277
Convertible Preferred Stock (in shares)	6,476,275	6,476,275
Total Potential Dilutive Shares (in shares)	17,270,377	17,105,849