Note 6 - Shareholders' Equity - Stock Option Activity (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares
Balance, number of shares (in shares) | shares	1,539,278
Balance, weighted average exercise price (in dollars per share) | $ / shares	$ 2.05
Balance, weighted average remaining contractual life (Year)	5 years 10 months 17 days	5 years 2 months 1 day
Balance, aggregate intrinsic value | $	$ 79,850	$ 43,783
Granted, number of shares (in shares) | shares	5,000
Granted, weighted average exercise price (in dollars per share) | $ / shares	$ 1.17
Exercised, number of shares (in shares) | shares	(24,167)
Exercised, weighted average exercise price (in dollars per share) | $ / shares	$ 1.02
Forfeited, number of shares (in shares) | shares	(45,495)
Forfeited, weighted average exercise price (in dollars per share) | $ / shares	$ 1.36
Expired, number of shares (in shares) | shares	(221,486)
Expired, weighted average exercise price (in dollars per share) | $ / shares	$ 1.91
Balance, number of shares (in shares) | shares	1,253,130	1,539,278
Balance, weighted average exercise price (in dollars per share) | $ / shares	$ 2.12	$ 2.05
Vested and expected to vest, number of shares (in shares) | shares	1,253,130
Vested and expected to vest, weighted average exercise price (in dollars per share) | $ / shares	$ 2.12
Vested and expected to vest, weighted average remaining contractual life (Year)	5 years 7 months 24 days
Vested and expected to vest, aggregate intrinsic value | $	$ 79,850
Exercisable, number of shares (in shares) | shares	1,050,994
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 2.23
Exercisable, weighted average remaining contractual life (Year)	5 years 6 months 14 days
Exercisable, aggregate intrinsic value | $	$ 62,661