Quarterly report pursuant to Section 13 or 15(d)

Note 11 - Common Stock (Details Textual)

v3.21.1
Note 11 - Common Stock (Details Textual) - USD ($)
1 Months Ended 2 Months Ended 3 Months Ended
Jan. 19, 2021
Jun. 08, 2020
Apr. 16, 2020
Mar. 31, 2021
Feb. 28, 2021
Mar. 31, 2020
Feb. 29, 2020
Mar. 31, 2021
Mar. 31, 2021
Mar. 31, 2020
Jan. 31, 2021
Jan. 18, 2021
Apr. 20, 2020
Nov. 30, 2019
May 22, 2017
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)       9,793,605       9,793,605 9,793,605            
Proceeds from Warrant Exercises                 $ 179,000 $ 1,661,000          
Stock Issued During Period, Share, Restricted Common Shares (in shares)           28,313     0            
Stock Issued During Period, Value, Restricted Common Shares           $ 24,000                  
Amortization of Debt Discount (Premium)                 $ 1,000 1,000          
Debt Instrument, Unamortized Discount, Total       $ 8,000       $ 8,000 8,000            
Fair Value Adjustment of Warrants                 $ 287,000          
Class of Warrant or Right Number of Securities Called by Warrants or Rights Cancelled In Period (in shares)                 0 0          
Class Of Warrant Or Right, Number Of Securities Called By Warrants Or Rights Expired In Period (in shares)                 0 0          
Series C Preferred Stock [Member]                              
Preferred Stock, Shares Outstanding, Ending Balance (in shares)       0       0 0            
Series B Warrants [Member]                              
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) $ 3.40                     $ 6.10      
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)       285,632       285,632 285,632            
Stock Issued During Period, Shares, Warrant Exercises (in shares)     24,279   40,000   4,548                
Proceeds from Warrant Exercises         $ 136,000   $ 70,000                
Warrants Issued in Connection with January 2021 Offering [Member]                              
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)                     1        
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)                     $ 3.40        
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) 8,117,640     8,104,880       8,104,880 8,104,880   8,117,640        
Stock Issued During Period, Shares, Warrant Exercises (in shares)               12,760              
Proceeds from Warrant Exercises               $ 43,000              
May 2017 Issuance Related to 2017 Loan Agreement [Member]                              
Warrants and Rights Outstanding, Term (Year)                             10 years
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)                             $ 9,500
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)                             223
Series A Warrants [Member]                              
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)       0       0 0            
Stock Issued During Period, Shares, Warrant Exercises (in shares)     482,059       102,626                
Proceeds from Warrant Exercises             $ 1,591,000                
Series A-2 and Series B-2 Warrants [Member]                              
Warrants and Rights Outstanding, Term (Year)                         5 years    
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares) 1                            
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) $ 3.40                     $ 6.371 $ 6.371    
Fair Value Adjustment of Warrants $ 287,000                            
January 2021 Offering Warrants [Member]                              
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)       8,104,880       8,104,880 8,104,880            
Stock Issued During Period, Shares, Warrant Exercises (in shares)       4,000 8,760                    
Proceeds from Warrant Exercises       $ 13,000 $ 30,000                    
Series A-2 Warrants [Member]                              
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)       392,830       392,830 392,830       482,059    
Stock Issued During Period, Shares, Warrant Exercises (in shares)                 392,830            
Series B-2 Warrants [Member]                              
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)       20,380       20,380 20,380       24,279    
Stock Issued During Period, Shares, Warrant Exercises (in shares)                 20,380            
Class A Units [Member] | Series B Warrants [Member]                              
Warrants and Rights Outstanding, Term (Year)                           5 years  
Class A Units [Member] | Warrants Issued in Connection with Class A Units [Member]                              
Warrants and Rights Outstanding, Term (Year) 5 years                            
Warrants Per Unit (in shares) 1                            
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares) 1                            
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) $ 3.40                            
Class B Units [Member] | Warrants Issued in Connection with Class B Units [Member]                              
Warrants and Rights Outstanding, Term (Year) 5 years                            
Warrants Per Unit (in shares) 1                            
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares) 1                            
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) $ 3.40                            
Purchase Agreement with LPC [Member]                              
Maximum Amount of Shares Issuable   $ 10,000,000                          
Stock Purchase Agreement Duration Period (Month)   2 years 180 days                          
Stock Purchase Agreement, Maximum Issuable Shares (in shares)   301,762                          
Stock Purchase Agreement, Maximum Issuable Shares, Percent of Outstanding Stock   19.99%                          
Stock Purchase Agreement, Share Price Covenant Trigger (in dollars per share)   $ 6.46                          
November 2019 Offering [Member] | Class B Units [Member]                              
Series A Convertible Preferred Stock Per Unit (in shares)                           1  
First Amendment to the LPC Purchase Agreement [Member]                              
Stock Purchase Agreement, Maximum Issuable Shares (in shares)       2,068,342       2,068,342 2,068,342            
Stock Purchase Agreement, Maximum Issuable Shares, Percent of Outstanding Stock       19.99%       19.99% 19.99%            
Stock Purchase Agreement, Share Price Covenant Trigger (in dollars per share)       $ 2.99       $ 2.99 $ 2.99            
January 2021 Offering [Member]                              
Proceeds from Issuance or Sale of Equity, Total $ 27,600,000                            
Shares Issued, Price Per Share (in dollars per share) $ 3.40                            
Proceeds from Issuance or Sale of Equity, Net of Issuance Costs $ 25,122,000                            
January 2021 Offering [Member] | Series C Preferred Stock [Member]                              
Stock Issued During Period, Shares, New Issues (in shares) 2,450,880                            
January 2021 Offering [Member] | Class A Units [Member]                              
Units Issued, Shares (in shares) 4,607,940                            
Shares Issued, Price Per Share (in dollars per share) $ 3.40                            
Common Shares Per Unit (in shares) 1                            
Warrants Per Unit (in shares) 1                            
January 2021 Offering [Member] | Class B Units [Member]                              
Units Issued, Shares (in shares) 2,450,880                            
Shares Issued, Price Per Share (in dollars per share) $ 3.40                            
Common Shares Per Unit (in shares) 1                            
Warrants Per Unit (in shares) 1                            
Over-Allotment Option [Member]                              
Stock Issued During Period, Shares, New Issues (in shares) 1,058,820                            
Over-Allotment Option [Member] | Warrants Issued in Connection with January 2021 Offering [Member]                              
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) 1,058,820