Note 10 - Net Loss Per Share - Schedule of Antidilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Number of potential common shares excluded (in shares)	8,636,343	4,908,613
Share-based Payment Arrangement, Option [Member]
Number of potential common shares excluded (in shares)	6,138,485	3,013,370
Series B Convertible Preferred Stock [Member]
Number of potential common shares excluded (in shares)	227,010	258,230
Warrant [Member]
Number of potential common shares excluded (in shares)	2,270,848	1,637,013