Note 3 - Summary of Significant Accounting Policies (Details Textual)	12 Months Ended
	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Jan. 01, 2019 USD ($)	Aug. 09, 2017 USD ($)
Number of Operating Segments	1
Cash, Uninsured Amount	$ 14,000,000
Accounts Receivable, Allowance for Credit Loss, Ending Balance	0	$ 0
Inventory Valuation Reserves, Ending Balance	500,000	1,000,000
Inventory, Net, Total	0	0
Finance Lease, Liability, Total	0
Revenue from Contract with Customer, Including Assessed Tax	565,464	753,108
Contract with Customer, Asset, before Allowance for Credit Loss, Total	$ 0	$ 0
Weighted Average Number Diluted Shares Outstanding Adjustment, Total | shares	0	0
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares	10,547,735	3,911,302
Operating Lease, Right-of-Use Asset	$ 618,158
Contract with Customer, Liability, Total	0	0
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset			$ 712,534
Operating Lease, Liability, Total			$ 789,543
Grant [Member]
Revenue from Contract with Customer, Including Assessed Tax	565,464	753,108
Term Loan Facility [Member] | Silicon Valley Bank (SVB) [Member]
Debt Instrument, Face Amount	$ 4,375,000	$ 7,500,000		$ 7,500,000