Note 5 - Share-based Compensation - Stock Option Activity (Details) - USD ($)		6 Months Ended	12 Months Ended
		Jun. 30, 2023	Dec. 31, 2022
Outstanding, shares (in shares)		5,031,097
Outstanding, weighted average exercise price (in dollars per share)		$ 3.25
Weighted-average remaining contractual term, outstanding (Year)		6 years 1 month 13 days	5 years 9 months
Aggregate intrinsic value, outstanding		$ 1,011,183	$ 13,000
Granted, shares (in shares)	[1]	745,350
Granted, weighted average exercise price (in dollars per share)		$ 1.43
Exercised, shares (in shares)		0
Exercised, weighted average exercise price (in dollars per share)		$ 0
Expired, shares (in shares)	[2]	(320,000)
Expired, weighted average exercise price (in dollars per share)		$ 1.62
Canceled, shares (in shares)		0
Canceled, weighted average exercise price (in dollars per share)		$ 0
Outstanding, shares (in shares)		5,456,447	5,031,097
Outstanding, weighted average exercise price (in dollars per share)		$ 3.10	$ 3.25
Exercisable, shares (in shares)		4,179,293
Exercisable, weighted average exercise price (in dollars per share)		$ 3.15
Weighted-average remaining contractual term, exercisable (Year)		5 years 3 months 25 days
Aggregate intrinsic value, exercisable		$ 621,865

[1] Represents the following stock options granted: • Annual share-based compensation awards on January 3, 2023, including: (a) 406,250 stock options with an exercise price of $1.38 per share granted to executives and key personnel, upon one year anniversary, or vesting annually in equal installments over four years, (b) 262,500 stock options with an exercise price of $1.38 per share granted to members of the Board of Directors, vesting upon one year anniversary, (c) 24,100 stock options with an exercise price of $1.38 per share granted to employees, vesting annually in equal installments over four years, (d) 15,000 stock options with an exercise price of $1.38 per share granted to a consultant, vesting upon one year anniversary, and (e) 37,500 stock options with an exercise price of $2.23 per share granted to a consultant, vesting over two months from the grant date.

[2] Represents the following stock options expired:•(a) 270,000 stock options with an exercise price of $1.39 per share granted to an executive, (b) 25,000 stock options with an exercise price of $1.75 per share granted to a member of the Board of Directors, and (c) 25,000 stock options with an exercise price of $3.99 per share granted to a consultant.