Note 6 - Shareholders' Equity - Stock Option Activity (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Balance, number of shares (in shares)	1,539,278
Balance, weighted average exercise price (in dollars per share)	$ 2.05
Balance, weighted average remaining contractual life (Year)	5 years 4 months 20 days	5 years 2 months 1 day
Balance, aggregate intrinsic value	$ 25,642	$ 43,783
Granted, number of shares (in shares)	0
Granted, weighted average exercise price (in dollars per share)	$ 0
Exercised, number of shares (in shares)	(24,167)
Exercised, weighted average exercise price (in dollars per share)	$ 1.02
Forfeited, number of shares (in shares)	(40,026)
Forfeited, weighted average exercise price (in dollars per share)	$ 1.39
Expired, number of shares (in shares)	(92,839)
Expired, weighted average exercise price (in dollars per share)	$ 2.75
Balance, number of shares (in shares)	1,382,246	1,539,278
Balance, weighted average exercise price (in dollars per share)	$ 2.05	$ 2.05
Vested and expected to vest, number of shares (in shares)	1,382,246
Vested and expected to vest, weighted average exercise price (in dollars per share)	$ 2.05
Vested and expected to vest, weighted average remaining contractual life (Year)	5 years 4 months 20 days
Vested and expected to vest, aggregate intrinsic value	$ 25,642
Exercisable, number of shares (in shares)	1,133,477
Exercisable, weighted average exercise price (in dollars per share)	$ 2.16
Exercisable, weighted average remaining contractual life (Year)	4 years 10 months 13 days
Exercisable, aggregate intrinsic value	$ 18,908