Quarterly report pursuant to Section 13 or 15(d)

Note 1 - The Company and Basis of Presentation (Details Textual)

v3.21.1
Note 1 - The Company and Basis of Presentation (Details Textual) - USD ($)
1 Months Ended 2 Months Ended 3 Months Ended
Jan. 19, 2021
Jun. 08, 2020
Apr. 20, 2020
Apr. 16, 2020
Feb. 28, 2021
Feb. 29, 2020
Mar. 31, 2021
Mar. 31, 2021
Mar. 31, 2020
Jan. 31, 2021
Jan. 18, 2021
Dec. 31, 2020
Dec. 16, 2020
Dec. 15, 2020
Apr. 15, 2020
Dec. 31, 2019
Nov. 30, 2019
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)             9,793,605 9,793,605                  
Proceeds from Warrant Exercises               $ 179,000 $ 1,661,000                
Fair Value Adjustment of Warrants               $ 287,000                
Preferred Stock, Shares Authorized (in shares)             10,000,000 10,000,000       10,000,000 [1]          
Payments of Warrant Issuance Costs     $ 334,000                            
Retained Earnings (Accumulated Deficit), Ending Balance             $ (225,617,000) $ (225,617,000)       $ (219,826,000) [2]          
Net Cash Provided by (Used in) Operating Activities, Total               (3,253,000) (5,736,000)                
Net Cash Provided by (Used in) Financing Activities, Total               25,261,000 $ 1,631,000                
Cash and Cash Equivalents, at Carrying Value, Ending Balance             28,446,000 28,446,000       $ 6,523,000 [2]          
Working Capital             $ 29,598,000 $ 29,598,000                  
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   8,117,640              
Stock Issued During Period, Shares, Warrant Exercises (in shares)             12,760                    
Proceeds from Warrant Exercises             $ 43,000                    
Series A and Series B Warrants [Member]                                  
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) $ 3.40                           $ 6.10 $ 15.50  
Proceeds from Warrant Exercises       $ 3,089,000                          
Series A-2 and Series B-2 Warrants [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   $ 6.371               $ 6.371            
Warrants and Rights Outstanding, Term (Year)     5 years                            
Fair Value Adjustment of Warrants $ 287,000                                
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                  
Stock Issued During Period, Shares, Warrant Exercises (in shares)       24,279 40,000 4,548                      
Proceeds from Warrant Exercises         $ 136,000 $ 70,000                      
Series A Warrants [Member]                                  
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)             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 Warrants [Member]                                  
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)     482,059       392,830 392,830                  
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)     24,279       20,380 20,380                  
Stock Issued During Period, Shares, Warrant Exercises (in shares)               20,380                  
Class A Units [Member] | Warrants Issued in Connection with Class A Units [Member]                                  
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                                
Warrants and Rights Outstanding, Term (Year) 5 years                                
Class A Units [Member] | Series B Warrants [Member]                                  
Warrants and Rights Outstanding, Term (Year)                                 5 years
Class B Units [Member] | Warrants Issued in Connection with Class B Units [Member]                                  
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                                
Warrants and Rights Outstanding, Term (Year) 5 years                                
Series C Preferred Stock [Member]                                  
Convertible Preferred Stock, Shares Issued upon Conversion (in shares)             1 1                  
Preferred Stock, Shares Outstanding, Ending Balance (in shares)             0 0                  
Preferred Stock, Par or Stated Value Per Share (in dollars per share)             $ 0.0001 $ 0.0001       $ 0.0001 [1]          
Series A Preferred Stock [Member]                                  
Convertible Preferred Stock, Shares Issued upon Conversion (in shares)             1 1                  
Preferred Stock, Shares Outstanding, Ending Balance (in shares)             0 0         0        
Preferred Stock, Shares Authorized (in shares)                           547,345      
Preferred Stock, Par or Stated Value Per Share (in dollars per share)                           $ 0.0001      
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                                
Proceeds From Issuance of Common Stock, Net               $ 25,122,000                  
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                                
Series C Convertible Preferred Stock Per Unit (in shares) 1                                
January 2021 Offering [Member] | Series C Preferred Stock [Member]                                  
Convertible Preferred Stock, Shares Issued upon Conversion (in shares) 1           1 1                  
Stock Issued During Period, Shares, New Issues (in shares) 2,450,880                                
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                                
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                              
First Amendment to the LPC Purchase Agreement [Member]                                  
Stock Purchase Agreement, Maximum Issuable Shares (in shares)             2,068,342 2,068,342                  
Stock Purchase Agreement, Maximum Issuable Shares, Percent of Outstanding Stock             19.99% 19.99%                  
Stock Purchase Agreement, Share Price Covenant Trigger (in dollars per share)             $ 2.99 $ 2.99                  
[1] The condensed consolidated balance sheet as of December 31, 2020 has been derived from the audited consolidated financial statements as of that date.
[2] The condensed consolidated balance sheet as of December 31, 2020 has been derived from the audited consolidated financial statements as of that date.