Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - $ / shares	Jun. 30, 2022	Dec. 31, 2021
Preferred stock, authorized (in shares)	15,000,000	15,000,000
Preferred stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, issued (in shares)	21,843,648	21,609,409
Common stock, outstanding (in shares)	21,843,648	21,609,409