Note 10 - Warrants - Summary of Outstanding Common Stock Purchase Warrants (Details)	Sep. 30, 2023 $ / shares shares
Class of warrants, exercisable (in shares) | shares	50,309
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 37.75
Warrants Expiring September 2023 [Member]
Class of warrants, exercisable (in shares) | shares	1,352
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 337.5
Warrants Expiring May 2024 [Member]
Class of warrants, exercisable (in shares) | shares	1,079
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 176.06
Warrants Expiring October 2024 [Member]
Class of warrants, exercisable (in shares) | shares	822
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 56.25
Warrants Expiring January 2025 [Member]
Class of warrants, exercisable (in shares) | shares	3,357
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 168.3
Warrants Expiring April 2028 [Member]
Class of warrants, exercisable (in shares) | shares	3,199
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 168.75
Warrants Expiring December 2025 [Member]
Class of warrants, exercisable (in shares) | shares	40,500
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 2.52