Note 9 - Stockholders' Equity (Details Textual) - USD ($) | Feb. 11, 2021 | Sep. 24, 2020 | Mar. 31, 2021 | Mar. 31, 2020 |
Stock Issued During Period, Shares, New Issues (in shares) | 1,644,000 | | | |
Shares Issued, Price Per Share (in dollars per share) | $ 6.25 | | | |
Proceeds from Issuance of Common Stock | $ 9,400,000 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares) | | | 0 | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares) | | | 602,000 | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Ending Balance (in dollars per share) | | | $ 2.79 | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term (Year) | | | 9 years 255 days | |
Proceeds from Warrant Exercises | | | $ 3,174,156 | |
Stock Issued During Period, Shares, Issued for Services (in shares) | | | 1,472 | |
Stock Issued During Period, Value, Issued for Services | | | $ 6,000 | $ 6,000 |
Stock Incentive Plan 2020 [Member] | | | | |
Common Stock, Capital Shares Reserved for Future Issuance (in shares) | | | 1,000,000 | |
Representative Warrants [Member] | | | | |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | 72,000 | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ 6.875 | | | |
Class of Warrant or Right, Period for Warrants or Rights Exercisable (Day) | | 180 days | | |
Warrants and Rights Outstanding, Term (Year) | | 3 years | | |
Stock Purchase Warrants First Issuance [Member] | | | | |
Class of Warrant or Right, Exercised During Period (in shares) | | | 188,688 | |
Stock Issued During Period, Shares, Warrants Exercised (in shares) | | | 145,866 | |
Stock Purchase Warrants Second Issuance [Member] | | | | |
Class of Warrant or Right, Exercised During Period (in shares) | | | 690,034 | |
Stock Issued During Period, Shares, Warrants Exercised (in shares) | | | 690,034 | |
Stock Purchase Warrants [Member] | | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | | | $ 5.07 | |
Warrants and Rights Outstanding, Term (Year) | | | 4 years 146 days | |
Class of Warrant or Right, Outstanding (in shares) | | | 2,793,635 | |
Over-Allotment Option [Member] | | | | |
Stock Issued During Period, Shares, New Issues (in shares) | 204,000 | | | |