Consolidated Statements of Stockholders' Equity (Parentheticals) - $ / shares |
Dec. 31, 2021 |
Dec. 31, 2020 |
|---|---|---|
| Warrants at $3.00 Per Share [Member] | ||
| Warrants, exercise price (in dollars per share) | $ 3.00 | |
| Warrants at $5.00 Per Share [Member] | ||
| Warrants, exercise price (in dollars per share) | 5.00 | |
| Warrants at $6.00 Per Share [Member] | ||
| Warrants, exercise price (in dollars per share) | 6.00 | |
| Warrants at $6.50 Per Share [Member] | ||
| Warrants, exercise price (in dollars per share) | $ 6.50 | 6.50 |
| Warrants at $8.125 Per Share [Member] | ||
| Warrants, exercise price (in dollars per share) | $ 8.125 | |
| Common stock and warrants, price per share (in dollars per share) | $ 6.00 |