Annual report pursuant to Section 13 and 15(d)

Stockholders' (Deficit) Equity (Details Textual)

v3.20.4
Stockholders' (Deficit) Equity (Details Textual)
1 Months Ended 12 Months Ended 20 Months Ended
Oct. 30, 2020
shares
Jun. 30, 2020
USD ($)
Oct. 10, 2019
USD ($)
$ / shares
shares
Sep. 19, 2019
Jun. 16, 2019
USD ($)
$ / shares
shares
May 08, 2019
shares
Feb. 19, 2019
USD ($)
$ / shares
shares
Jan. 31, 2019
USD ($)
$ / shares
shares
Dec. 31, 2020
USD ($)
$ / shares
shares
Dec. 31, 2019
USD ($)
$ / shares
shares
Dec. 31, 2020
USD ($)
$ / shares
shares
Feb. 28, 2019
$ / shares
shares
Dec. 31, 2018
$ / shares
shares
Shares vested (in shares)             127,500            
Granted (in shares)                 1,036,000 648,550      
Granted, weighted average exercise price (in dollars per share) | $ / shares                 $ 9.38 $ 6.03      
Share price (in dollars per share) | $ / shares             $ 4.87            
Deferred compensation expense | $               $ 500,000 $ 7,900,000        
Number of shares of common stock to be called by each warrant (in shares)     533,775       452,081            
Exercise price of warrants (in dollars per share) | $ / shares                 $ 11.32 $ 10.97 $ 11.32   $ 1.75
Warrant term (in years)     5 years                    
Warrants outstanding | $     $ 4,500,000       $ 800,000            
Proceeds from issuance of common stock | $         $ 9,500,000   10,900,000   $ 32,046,000 $ 24,096,000      
Private Investment in Public Equity Offering                          
Exercise price of warrants (in dollars per share) | $ / shares         $ 16.00                
Number of units issued     485,250   675,000                
Number of common stock per unit     1   1                
Number of warrants per unit     1.1   0.7                
Proceeds from warrant exercises | $         $ 8,600,000                
Proceeds from private investment in public equity offering | $     $ 5,700,000                    
June 2020 Offering                          
Proceeds from issuance of common stock | $   $ 35,000,000.0                      
Convertible Debt | Fifth Note                          
Unamortized discount | $             700,000            
Warrants Issued With Non-Convertible Notes Prior To IPO | Fifth Note                          
Unamortized discount | $             500,000            
Convertible Notes Payable | Fifth Note                          
Unamortized discount | $             100,000            
Warrants Issued With Convertible Notes | Fifth Note                          
Unamortized discount | $             $ 100,000            
Discount Rate                          
Measurement input     0.0159                    
Expected Dividend Payment                          
Measurement input | $                   0      
Share Price                          
Measurement input     12.88       1.67            
Fifth Note                          
Number of shares of common stock to be called by each warrant (in shares)               300,000       300,000  
Exercise price of warrants (in dollars per share) | $ / shares               $ 1.75       $ 1.75  
Warrants Issued to Underwriters                          
Number of shares of common stock to be called by each warrant (in shares)             152,081            
Exercise price of warrants (in dollars per share) | $ / shares             $ 6.00            
Warrant term (in years)             5 years            
Warrants Issued in Private Investment in Public Equity Offering                          
Number of shares of common stock to be called by each warrant (in shares)         472,500                
Exercise price of warrants (in dollars per share) | $ / shares     $ 12.88   $ 14.00                
Warrants outstanding | $         $ 4,400,000                
Proceeds from issuance of common stock | $     $ 6,300,000                    
Warrants Issued in Private Investment in Public Equity Offering | Discount Rate                          
Measurement input         0.0185                
Warrants Issued in Private Investment in Public Equity Offering | Expected Term                          
Measurement input         5                
Warrants Issued in Private Investment in Public Equity Offering | Price Volatility                          
Measurement input         0.8494                
Warrants Issued in Private Investment in Public Equity Offering | Expected Dividend Payment                          
Measurement input         0                
Warrants Issued in Private Investment in Public Equity Offering | Share Price                          
Measurement input         14.30                
Minimum | Discount Rate                          
Measurement input             0.0247            
Minimum | Price Volatility                          
Measurement input     0.8292       0.8409            
Maximum | Discount Rate                          
Measurement input             0.0280            
Maximum | Price Volatility                          
Measurement input             0.8445            
Restricted Stock                          
Grants in period (in shares)                 200,000 200,000      
Shares vested (in shares)                 49,992 169,164      
Shares that immediately vested upon completion of IPO (in shares)                 308,344 158,336 308,344   127,500
Unamortized expense related to restricted stock grant | $                 $ 2,500,000   $ 2,500,000    
Cost not yet recognized, period for recognition                 3 years 3 months 21 days        
Stock-based compensation expense | $                 $ 600,000 $ 900,000      
Restricted Stock | Share-based Payment Arrangement, Tranche One                          
Shares vested (in shares)           25,000              
Restricted Stock | Share-based Payment Arrangement, Tranche Two                          
Shares vested (in shares)                 175,000        
Vesting period (in years)           4 months              
Employee Stock Option                          
Cost not yet recognized, period for recognition                 2 years 4 months 20 days        
Expiration period (in years)               10 years   10 years      
Fair value of options | $               $ 500,000 $ 7,000,000.0 $ 2,800,000      
Discount rate               2.53%          
Expected life (in years)               5 years 3 months 7 days          
Expected volatility rate               84.30%          
Expected dividends | $               $ 0 0        
Stock-based compensation expense | $                 $ 2,600,000 $ 1,600,000      
Employee Stock Option | Minimum                          
Expiration period (in years)                 1 year        
Discount rate                 0.10% 1.65%      
Expected life (in years)                 5 years 6 months 5 years 6 months      
Expected volatility rate                 83.10% 82.99%      
Share price (in dollars per share) | $ / shares               $ 1.67 $ 6.44 $ 5.73 $ 6.44    
Employee Stock Option | Maximum                          
Expiration period (in years)                 10 years        
Discount rate                 1.60% 2.12%      
Expected life (in years)                 6 years 3 months 6 years 3 months      
Expected volatility rate                 83.40% 85.06%      
Share price (in dollars per share) | $ / shares                 $ 13.50 $ 17.50 $ 13.50    
Employee Stock Option | Share-based Payment Arrangement, Tranche One                          
Vesting period (in years)       42 months       1 year   1 year      
Employee Stock Option | Share-based Payment Arrangement, Tranche One | Minimum                          
Award vesting rights, percentage                 8.33%        
Employee Stock Option | Share-based Payment Arrangement, Tranche One | Maximum                          
Award vesting rights, percentage                 25.00%        
Employee Stock Option | Share-based Payment Arrangement, Tranche Two                          
Vesting period (in years)                   4 years      
Award vesting rights, percentage               25.00%   25.00%      
Employee Stock Option | Share-based Payment Arrangement, Tranche Two | Maximum                          
Vesting period (in years)                 4 years        
Three Consultants | Restricted Stock                          
Grants in period (in shares)           200,000              
Shares vested (in shares)                     91,656    
Shares that immediately vested upon completion of IPO (in shares)                 108,344   108,344    
Chief Executive Officer | Restricted Stock                          
Grants in period (in shares) 200,000                        
Shares that immediately vested upon completion of IPO (in shares)                 200,000   200,000    
Award vesting rights, percentage 25.00%                        
Certain Individuals                          
Granted (in shares)               401,750 1,036,000 246,800      
Granted, weighted average exercise price (in dollars per share) | $ / shares               $ 1.75 $ 9.38 $ 13.00      
Deferred compensation expense | $               $ 400,000          
2018 Stock Plan                          
Shares reserved and available for issuance (in shares)                 4,150,000   4,150,000    
Shares remaining available for grant (in shares)                 45,450   45,450