Annual report pursuant to Section 13 and 15(d)

Note 8 - Warrant Liability (Details Textual)

v3.19.1
Note 8 - Warrant Liability (Details Textual)
1 Months Ended 12 Months Ended
Mar. 29, 2018
$ / shares
shares
Dec. 18, 2017
$ / shares
shares
Apr. 17, 2017
$ / shares
shares
Feb. 28, 2018
USD ($)
shares
Feb. 29, 2016
USD ($)
shares
Dec. 31, 2018
USD ($)
shares
Dec. 31, 2017
USD ($)
shares
Feb. 29, 2016
$ / shares
Feb. 29, 2016
USD ($)
shares
Proceeds from Warrant Exercises | $           $ 607,000 $ 615,000    
Warrants and Rights Outstanding | $           $ 84,000    
Stock Issued During Period, Shares, Exercise of Common Stock Warrants           128,594 134,079    
Warrants Issued in Private Placement [Member]                  
Class of Warrant or Right, Outstanding                 117,188
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right 1 1 1           1
Class of Warrant or Right, Exercise Price of Warrants or Rights | (per share) $ 7 $ 7 $ 4.60         $ 5  
Proceeds from Warrant Exercises | $         $ 281,000        
Stock Issued During Period, Shares, Exercise of Common Stock Warrants             131,578    
Warrants Issued in Private Placement [Member] | Measurement Input, Price Volatility [Member] | Minimum [Member]                  
Warrants and Rights Outstanding, Measurement Input                 1.918
Warrants Issued in Private Placement [Member] | Measurement Input, Price Volatility [Member] | Maximum [Member]                  
Warrants and Rights Outstanding, Measurement Input                 2.25
Warrants Issued in Private Placement [Member] | Measurement Input, Risk Free Interest Rate [Member] | Minimum [Member]                  
Warrants and Rights Outstanding, Measurement Input                 0.0043
Warrants Issued in Private Placement [Member] | Measurement Input, Risk Free Interest Rate [Member] | Maximum [Member]                  
Warrants and Rights Outstanding, Measurement Input                 0.0049
Warrants Issued in Private Placement [Member] | Measurement Input, Expected Term [Member]                  
Warrants and Rights Outstanding, Measurement Input                 2
Compensation Warrants Issued In Connection With Private Placement [Member]                  
Class of Warrant or Right, Outstanding                 10,915
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right                 1
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares               $ 5  
Proceeds from Warrant Exercises | $       $ 483,000          
Warrants and Rights Outstanding, Term                 2 years
Warrants and Rights Outstanding | $                 $ 24,000
Stock Issued During Period, Shares, Exercise of Common Stock Warrants       121,256          
Class of Warrant or Right, Warrants Expired During Period       4,346          
Compensation Warrants Issued In Connection With Private Placement [Member] | Measurement Input, Price Volatility [Member]                  
Warrants and Rights Outstanding, Measurement Input       0.167          
Compensation Warrants Issued In Connection With Private Placement [Member] | Measurement Input, Price Volatility [Member] | Minimum [Member]                  
Warrants and Rights Outstanding, Measurement Input                 1.918
Compensation Warrants Issued In Connection With Private Placement [Member] | Measurement Input, Price Volatility [Member] | Maximum [Member]                  
Warrants and Rights Outstanding, Measurement Input                 2.25
Compensation Warrants Issued In Connection With Private Placement [Member] | Measurement Input, Risk Free Interest Rate [Member]                  
Warrants and Rights Outstanding, Measurement Input       0.018          
Compensation Warrants Issued In Connection With Private Placement [Member] | Measurement Input, Risk Free Interest Rate [Member] | Minimum [Member]                  
Warrants and Rights Outstanding, Measurement Input                 0.0043
Compensation Warrants Issued In Connection With Private Placement [Member] | Measurement Input, Risk Free Interest Rate [Member] | Maximum [Member]                  
Warrants and Rights Outstanding, Measurement Input                 0.0049
Compensation Warrants Issued In Connection With Private Placement [Member] | Measurement Input, Expected Term [Member]                  
Warrants and Rights Outstanding, Measurement Input                 2
Compensation Warrants Issued In Connection With Private Placement [Member] | Measurement Input, Expected Term [Member] | Minimum [Member]                  
Warrants and Rights Outstanding, Measurement Input       0.01          
Compensation Warrants Issued In Connection With Private Placement [Member] | Measurement Input, Expected Term [Member] | Maximum [Member]                  
Warrants and Rights Outstanding, Measurement Input       0.03          
Private Placement [Member]                  
Units Issued During Period, Units, New Issues 1,322,965 181,220 526,316   234,375        
Units, Number of Common Shares Per Unit 1 1 1           1
Units, Number of Common Share Purchase Warrant Per Unit 0.5 0.5 0.5           0.5