STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($)
Common Stock
Additional paid-in capital
Treasury stocks
Accumulated Deficit
Total
Balance at Dec. 31, 2019 $ 11,000 $ 105,042,000   $ (117,276,000) $ (12,223,000)
Balance (in shares) at Dec. 31, 2019 23,174,228        
Stock-based compensation related to stock and options granted to directors and employees   390,000   0 390,000
Stock-based compensation related to stock and options granted to directors and employees (in shares) 54,956        
Issuance of shares in at-the-market (ATM) offering $ 1,000 18,971,000   0 18,972,000
Issuance of shares in at-the-market (ATM) offering (in shares) 3,935,320        
Issuance of shares and warrants in Registered Direct Offering   9,957,000   0 9,957,000
Issuance of shares and warrants in Registered Direct Offering (in shares) 1,250,000        
Exercise of options   29,000   0 29,000
Exercise of options (in shares) 9,333        
Net loss $ 0 0   (8,114,000) (8,114,000)
Balance at Mar. 31, 2020 $ 12,000 134,389,000   (125,390,000) 9,011,000
Balance (in shares) at Mar. 31, 2020 28,423,837        
Balance at Dec. 31, 2019 $ 11,000 105,042,000   (117,276,000) (12,223,000)
Balance (in shares) at Dec. 31, 2019 23,174,228        
Net loss         (19,996,000)
Balance at Sep. 30, 2020 $ 12,000 163,238,000   (137,272,000) 25,978,000
Balance (in shares) at Sep. 30, 2020 31,567,592        
Balance at Mar. 31, 2020 $ 12,000 134,389,000   (125,390,000) 9,011,000
Balance (in shares) at Mar. 31, 2020 28,423,837        
Stock-based compensation related to stock and options granted to directors and employees   791,000   0 791,000
Stock-based compensation related to stock and options granted to directors and employees (in shares) 79,491        
Issuance of shares in at-the-market (ATM) offering   7,411,000   0 7,411,000
Issuance of shares in at-the-market (ATM) offering (in shares) 1,162,527        
Exercise of options   3,000   0 3,000
Exercise of options (in shares) 4,000        
Net loss $ 0 0   (7,394,000) (7,394,000)
Balance at Jun. 30, 2020 $ 12,000 142,594,000   (132,784,000) 9,822,000
Balance (in shares) at Jun. 30, 2020 29,669,855        
Stock-based compensation related to stock and options granted to directors and employees   1,017,000   0 1,017,000
Stock-based compensation related to stock and options granted to directors and employees (in shares) 45,797        
Issuance of shares in at-the-market (ATM) offering   13,307,000   0 13,307,000
Issuance of shares in at-the-market (ATM) offering (in shares) 947,627        
Exercise of options   20,000   0 20,000
Exercise of options (in shares) 4,313        
Exercise of warrants   6,300,000   0 6,300,000
Exercise of warrants (in shares) 900,000        
Net loss $ 0 0   (4,488,000) (4,488,000)
Balance at Sep. 30, 2020 $ 12,000 163,238,000   (137,272,000) 25,978,000
Balance (in shares) at Sep. 30, 2020 31,567,592        
Balance at Dec. 31, 2020 $ 12,000 [1] 184,655,000 $ (116,000) (149,087,000) 35,464,000
Balance (in shares) at Dec. 31, 2020 35,159,977        
Stock-based compensation related to stock and options granted to directors and employees   290,000 0 0 290,000
Stock-based compensation related to stock and options granted to directors and employees (in shares) 0        
Issuance of shares in at-the-market (ATM) offering   7,104,000     7,104,000
Issuance of shares in at-the-market (ATM) offering (in shares) 1,156,897        
Exercise of options   5,000 0   5,000
Exercise of options (in shares) 1,687        
Net loss       (6,662,000) (6,662,000)
Balance at Mar. 31, 2021 $ 12,000 [1] 192,054,000 (116,000) (155,749,000) 36,201,000
Balance (in shares) at Mar. 31, 2021 36,318,561        
Balance at Dec. 31, 2020 $ 12,000 [1] 184,655,000 (116,000) (149,087,000) 35,464,000
Balance (in shares) at Dec. 31, 2020 35,159,977        
Net loss         (18,267,000)
Balance at Sep. 30, 2021 $ 12,000 [1] 192,384,000 (116,000) (167,354,000) 24,926,000
Balance (in shares) at Sep. 30, 2021 36,277,953        
Balance at Mar. 31, 2021 $ 12,000 [1] 192,054,000 (116,000) (155,749,000) 36,201,000
Balance (in shares) at Mar. 31, 2021 36,318,561        
Stock-based compensation related to stock and options granted to directors and employees   240,000     240,000
Net loss       (6,269,000) (6,269,000)
Balance at Jun. 30, 2021 $ 12,000 [1] 192,294,000 (116,000) (162,018,000) 30,172,000
Balance (in shares) at Jun. 30, 2021 36,318,561        
Stock-based compensation related to stock and options granted to directors and employees   196,000     196,000
Stock-based compensation related to stock and options granted to directors and employees (in shares) (40,608)        
Issuance costs related to at-the-market (ATM) offering (Note 7)   (106,000)     (106,000)
Net loss       (5,336,000) (5,336,000)
Balance at Sep. 30, 2021 $ 12,000 [1] $ 192,384,000 $ (116,000) $ (167,354,000) $ 24,926,000
Balance (in shares) at Sep. 30, 2021 36,277,953        
[1] Represents an amount less than $1.