Note 9 - Fair Value Measurements - Fair Value Liabilities Measured on Recurring Basis Unobservable Input Reconciliation (Details) - Fair Value, Inputs, Level 3 [Member] - Fair Value, Recurring [Member] - USD ($) |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2022 |
Jun. 30, 2021 |
Jun. 30, 2022 |
Jun. 30, 2021 |
|
| Balance, beginning of period | $ 283,720 | $ 1,040,305 | $ 372,730 | $ 1,963,785 |
| Change in fair value of warrant liability | (178,021) | (189,146) | (267,031) | (1,112,626) |
| Balance, end of period | $ 105,699 | $ 851,159 | $ 105,699 | $ 851,159 |