Note 5 - Stockholders' Equity (Details Textual) - USD ($) | Mar. 16, 2021 | Mar. 05, 2021 | May 15, 2020 | Feb. 20, 2019 | Aug. 09, 2017 | Mar. 31, 2021 | Mar. 31, 2020 | Dec. 31, 2020 | Nov. 30, 2020 | Sep. 13, 2018 | Jun. 30, 2017 |
Dividends, Preferred Stock, Total | | | | | | $ 322,271 | $ 320,290 | | | | |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | | | | | | | | | | | 2,646,091 |
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | | | | | | | | | | | $ 7.50 |
Warrants and Rights Outstanding, Term (Year) | | | | | | | | | | | 10 years |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares) | | | | | | 54,000 | | | | | |
Share-based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount | | | | | | $ 4,400,000 | | | | | |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year) | | | | | | 2 years 73 days | | | | | |
Share-based Payment Arrangement, Expense | | | | | | $ 573,722 | 272,537 | | | | |
The 2018 Incentive Plan [Member] | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares) | | | | | | | | | | 3,000,000 | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares) | | | | | | 54,000 | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Granted in Period, Fair Value | | | | | | $ 200,000 | | | | | |
The 2018 Incentive Plan [Member] | Employees [Member] | Share-based Payment Arrangement, Option [Member] | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Discount Rate | | | | | | 0.62% | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term (Year) | | | | | | 6 years | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate | | | | | | 87.00% | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate | | | | | | 0.00% | | | | | |
Warrants Issued in Connection with Term Loan Facility [Member] | | | | | | | | | | | |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | | | | | 58,502 | | | | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | | | | | $ 6.41 | | | | | | |
Class of Warrant or Right, Term (Year) | | | | | 10 years | | | | | | |
Series A Preferred Stock [Member] | | | | | | | | | | | |
Stock Issued During Period, Shares, New Issues (in shares) | | | | 15,000 | | | | | | | |
Shares Issued, Price Per Share (in dollars per share) | | | | $ 1,000 | | | | | | | |
Proceeds from Issuance of Private Placement | | | | $ 15,000,000 | | | | | | | |
Preferred Stock, Convertible, Conversion Price (in dollars per share) | | | | $ 2.60 | | | | | | | |
Preferred Stock, Dividend Rate, Percentage | | | | 8.00% | | | | | | | |
Preferred Stock, Liquidation Preference, Value | | | | $ 1,000 | | | | | | | |
Temporary Equity, Par Value | | | | | | $ 13,700,000 | | | | | |
Payments of Stock Issuance Costs | | | | | | 1,300,000 | | | | | |
Dividends, Preferred Stock, Total | | | | | | $ 217,206 | $ 320,290 | | | | |
Preferred Stock, Dividends Per Share, Declared (in dollars per share) | | | | | | $ 0.01 | $ 0.03 | | | | |
Series B Preferred Stock [Member] | | | | | | | | | | | |
Shares Issued, Price Per Share (in dollars per share) | | | $ 1,000 | | | | | | | | |
Preferred Stock, Convertible, Conversion Price (in dollars per share) | | | $ 3.10 | | | | | | | | |
Preferred Stock, Dividend Rate, Percentage | | | 8.00% | | | | | | | | |
Preferred Stock, Liquidation Preference, Value | | | $ 1,000 | | | | | | | | |
Temporary Equity, Par Value | | | | | | | | $ 7,700,000 | | | |
Payments of Stock Issuance Costs | | | | | | $ 105,065 | | $ 300,000 | | | |
Dividends, Preferred Stock, Total | | | | | | $ 0 | | | | | |
Preferred Stock, Dividends Per Share, Declared (in dollars per share) | | | | | | $ 0.01 | | | | | |
Public Offering [Member] | | | | | | | | | | | |
Stock Issued During Period, Shares, New Issues (in shares) | | 7,875,000 | | | | | | | | | |
Shares Issued, Price Per Share (in dollars per share) | | $ 8 | | | | | | | | | |
Proceeds from Issuance of Common Stock | | $ 63,000,000 | | | | | | | | | |
Proceeds from Issuance of Common Stock, Net of Discounts and Issuance Costs | | $ 59,000,000 | | | | | | | | | |
Over-Allotment Option [Member] | | | | | | | | | | | |
Stock Issued During Period, Shares, New Issues (in shares) | 1,049,700 | | | | | | | | | | |
Proceeds from Issuance of Common Stock | $ 8,400,000 | | | | | | | | | | |
Proceeds from Issuance of Common Stock, Net of Discounts and Issuance Costs | $ 7,900,000 | | | | | | | | | | |
Sale of Stock, Option to Purchase Shares (in shares) | | 1,181,250 | | | | | | | | | |
Private Placement [Member] | | | | | | | | | | | |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | | | | | | | | | 5,230,910 | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | | | | | | | | | $ 4.31 | | |
Warrants and Rights Outstanding, Term (Year) | | | | | | | | | 5 years | | |
Private Placement [Member] | Series B Preferred Stock [Member] | | | | | | | | | | | |
Stock Issued During Period, Shares, New Issues (in shares) | | | 8,000 | | | | | | | | |
Proceeds from Issuance of Private Placement | | | $ 8,000,000 | | | | | | | | |