Note 8 - Warrants (Details Textual) - Warrant In Connection with Oxford Finance Loan Agreement [Member] - $ / shares |
Sep. 30, 2020 |
May 30, 2019 |
|---|---|---|
| Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | 176,679 | |
| Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ 2.83 | |
| Class of Warrant or Right, Outstanding (in shares) | 176,679 |