Note 3 - Basis of Presentation and Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2020

Notes Tables

Fair Value Measurements, Recurring and Nonrecurring [Table Text Block]

	March 31, 2020
	(Level 1)		(Level 2)		(Level 3)
Assets
Cash equivalents	$	25,383,744	$	—	$	—

	December 31, 2019
	(Level 1)		(Level 2)		(Level 3)
Assets
Cash equivalents	$	14,006,193	$	—	$	—

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	Six Months Ended June 30,
	2020		2019
Common stock warrants		9,117,209		3,469,925
Stock options		1,427,829		309,276
Unvested restricted stock awards		98,100		—
		10,643,138		3,779,201