Note 6 - Stockholders' Equity - Summary of Option Activity (Details) - Share-Based Payment Arrangement, Option [Member] - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Share-Based Payment Arrangement, Employee [Member]
Number of options (in shares)	3,036,989
Weighted average exercise price, outstanding (in dollars per share)	$ 2.29
Weighted average remaining contractual life, outstanding (Year)	5 years 1 month 28 days	5 years 4 months 28 days
Aggregate intrinsic value, outstanding		$ 0
Number of options granted (in shares)	0
Number of options exercised (in shares)	0
Weighted average exercise price, exercised (in dollars per share)	$ 0
Number of options forfeited and expired (in shares)	0
Weighted average exercise price, forfeited or expired (in dollars per share)	$ 0
Number of options (in shares)	3,036,989	3,036,989
Weighted average exercise price, outstanding (in dollars per share)	$ 2.29	$ 2.29
Number of options exercisable (in shares)	1,788,433
Weighted average exercise price, exercisable (in dollars per share)	$ 2.24
Weighted average remaining contractual life, exercisable (Year)	3 years 11 months 15 days
Share-Based Payment Arrangement, Nonemployee [Member]
Number of options (in shares)	91,633
Weighted average exercise price, outstanding (in dollars per share)	$ 1.76
Weighted average remaining contractual life, outstanding (Year)	2 years 2 months 8 days	2 years 3 months
Aggregate intrinsic value, outstanding	$ 0	$ 2,833
Number of options granted (in shares)	8,333
Number of options exercised (in shares)	0
Weighted average exercise price, exercised (in dollars per share)	$ 0
Number of options forfeited and expired (in shares)	(8,333)
Weighted average exercise price, forfeited or expired (in dollars per share)	$ 0.35
Number of options (in shares)	91,633	91,633
Weighted average exercise price, outstanding (in dollars per share)	$ 1.79	$ 1.76
Number of options exercisable (in shares)	80,551
Weighted average exercise price, exercisable (in dollars per share)	$ 1.94
Weighted average remaining contractual life, exercisable (Year)	1 year 10 months 24 days
Weighted average exercise price, granted (in dollars per share)	$ 0.64
Weighted average remaining contractual life, granted (Year)	4 years 10 months 6 days
Aggregate intrinsic value, exercisable	$ 0