Note 6 - Shareholders' Equity - Stock Option Activity (Details)	9 Months Ended	12 Months Ended
	Sep. 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 8 months 1 day	5 years 2 months 1 day
Balance, aggregate intrinsic value | $	$ 41,866	$ 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	(26,198)
Exercised, weighted average exercise price (in dollars per share) | $ / shares	$ 1.02
Forfeited, number of shares (in shares) | shares	(46,890)
Forfeited, weighted average exercise price (in dollars per share) | $ / shares	$ 1.35
Expired, number of shares (in shares) | shares	(287,218)
Expired, weighted average exercise price (in dollars per share) | $ / shares	$ 2.15
Balance, number of shares (in shares) | shares	1,183,972	1,539,278
Balance, weighted average exercise price (in dollars per share) | $ / shares	$ 2.08	$ 2.05
Vested and expected to vest, number of shares (in shares) | shares	1,183,972
Vested and expected to vest, weighted average exercise price (in dollars per share) | $ / shares	$ 2.08
Vested and expected to vest, weighted average remaining contractual life (Year)	5 years 8 months 1 day
Vested and expected to vest, aggregate intrinsic value | $	$ 41,866
Exercisable, number of shares (in shares) | shares	1,025,464
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 2.16
Exercisable, weighted average remaining contractual life (Year)	5 years 4 months 17 days
Exercisable, aggregate intrinsic value | $	$ 36,283