Note 6 - Stockholders' Equity - Summary of Option Activity for Employees (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Aggregate intrinsic value, outstanding		$ 1,083
Share-Based Payment Arrangement, Option [Member] | Share-Based Payment Arrangement, Employee [Member]
Options outstanding, balance (in shares)	3,059,989
Weighted average exercise price, outstanding (in dollars per share)	$ 2.36
Weighted average remaining contractual life, outstanding (Year)	6 years 1 month 17 days	6 years 4 months 17 days
Aggregate intrinsic value, outstanding	$ 0
Granted, options (in shares)	0
Weighted average exercise price, granted (in dollars per share)	$ 0
Exercised, options (in shares)	0
Weighted average exercise price, exercised (in dollars per share)	$ 0
Forfeited and expired, options (in shares)	0
Weighted average exercise price, forfeited or expired (in dollars per share)	$ 0
Options outstanding, balance (in shares)	3,059,989	3,059,989
Weighted average exercise price, outstanding (in dollars per share)	$ 2.36	$ 2.36
Exercisable, options (in shares)	1,081,651
Weighted average exercise price, exercisable (in dollars per share)	$ 2.16
Weighted average remaining contractual life, exercisable (Year)	4 years 6 months 18 days
Exercised, options (in shares)	(0)
Share-Based Payment Arrangement, Option [Member] | Share-Based Payment Arrangement, Nonemployee [Member]
Options outstanding, balance (in shares)	91,663
Weighted average exercise price, outstanding (in dollars per share)	$ 1.75
Weighted average remaining contractual life, outstanding (Year)	2 years 6 months 10 days	2 years 6 months 18 days
Aggregate intrinsic value, outstanding	$ 8,583
Granted, options (in shares)	8,333
Weighted average exercise price, granted (in dollars per share)	$ 0.89
Exercised, options (in shares)	0
Weighted average exercise price, exercised (in dollars per share)	$ 0
Options outstanding, balance (in shares)	99,996	91,663
Weighted average exercise price, outstanding (in dollars per share)	$ 1.68	$ 1.75
Exercisable, options (in shares)	86,109
Weighted average exercise price, exercisable (in dollars per share)	$ 1.78
Weighted average remaining contractual life, exercisable (Year)	2 years 2 months 15 days
Weighted average remaining contractual life, granted (Year)	4 years 11 months 26 days
Exercised, options (in shares)	0
Aggregate intrinsic value, exercisable	$ 7,583