Quarterly report pursuant to Section 13 or 15(d)

Convertible Preferred Stock and Stockholders' Equity - Warrants for shares of common stock (Details)

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Convertible Preferred Stock and Stockholders' Equity - Warrants for shares of common stock (Details)
 1 Months Ended 3 Months Ended 12 Months Ended
Apr. 23, 2020
$ / shares
shares
Apr. 30, 2020
USD ($)
$ / shares
shares
Mar. 31, 2020
USD ($)
$ / shares
shares
Mar. 31, 2021
USD ($)
$ / shares
shares
Dec. 31, 2020
$ / shares
shares
Jan. 31, 2021
USD ($)
$ / shares
shares
Nov. 09, 2020
$ / shares
shares
Feb. 06, 2020
shares
Apr. 18, 2019
shares
Class of Stock [Line Items]                  
Warrants to purchase shares of Common Stock | shares               4,553 12,756
Exercise price of warrants | $ / shares             $ 2.55    
Fair value of warrant           $ 567,000      
Common Stock Price | $ / shares           $ 3.85      
Common Shares                  
Class of Stock [Line Items]                  
Warrants to purchase shares of Common Stock | shares             236,369    
Shares issued on exercise of warrants | shares       2,086,251          
LTSI                  
Class of Stock [Line Items]                  
Number of shares available for grant | shares       672,180          
June 4th Purchase Agreement                  
Class of Stock [Line Items]                  
Warrants to purchase shares of Common Stock | shares       2,275,000          
Exercise price of warrants | $ / shares       $ 2.55          
Fair value of warrant       $ 3,153,000          
Common Stock Price | $ / shares       $ 2.52          
June 8th Purchase Agreement                  
Class of Stock [Line Items]                  
Warrants to purchase shares of Common Stock | shares       2,040,000          
Exercise price of warrants | $ / shares       $ 2.61          
Fair value of warrant       $ 2,375,000          
Common Stock Price | $ / shares       $ 2.25          
January 2021 [Member]                  
Class of Stock [Line Items]                  
Warrants to purchase shares of Common Stock | shares       864,576          
April 2020 public offering                  
Class of Stock [Line Items]                  
Warrants to purchase shares of Common Stock | shares   1,525,000              
Exercise price of warrants | $ / shares $ 3.25 $ 0.01              
Fair value of warrant   $ 475,000              
Common Stock Price | $ / shares   $ 2.50              
Combined shares price | $ / shares $ 3.24 $ 3.25              
Deemed dividend from warrant repricing   $ 2,606,000   $ 134,000          
Shares issued on exercise of warrants | shares   475,000              
Proceeds from Issuance of Warrants   $ 4,750              
Option To Purchase Additional Shares Or Warrants | shares 300,000                
Warrant [Member] | January 2021 [Member]                  
Class of Stock [Line Items]                  
Warrants to purchase shares of Common Stock | shares           1,221,675      
Exercise price of warrants | $ / shares           $ 4.20      
March 2020 Warrant                  
Class of Stock [Line Items]                  
Warrants to purchase shares of Common Stock | shares     227,679            
Exercise price of warrants | $ / shares     $ 6.40            
Fair value of warrant     $ 625,000            
Common Stock Price | $ / shares     $ 5.40            
Fair Value Expected Term     5 years            
March 2020 Maxim Warrant                  
Class of Stock [Line Items]                  
Warrants to purchase shares of Common Stock | shares     20,400            
Prefunded common stock purchase warrants | April 2020 public offering                  
Class of Stock [Line Items]                  
Warrants to purchase shares of Common Stock | shares   291,000              
Common stock purchase warrants | April 2020 public offering                  
Class of Stock [Line Items]                  
Warrants to purchase shares of Common Stock | shares 475,000                
Exercise price of warrants | $ / shares   $ 3.25              
Option To Purchase Additional Shares Or Warrants | shares 229,100                
April 2020 Maxim Warrant                  
Class of Stock [Line Items]                  
Warrants to purchase shares of Common Stock | shares   100,000   15,000 15,000        
Exercise price of warrants | $ / shares   $ 3.90              
Fair value of warrant   $ 106,000              
Common Stock Price | $ / shares   $ 2.50   $ 15.80 $ 15.80        
Combined shares price | $ / shares       $ 0.20 $ 0.20        
Shares issued on exercise of warrants | shares       20,722 20,722        
April 2020 Maxim Warrant | April 2020 public offering                  
Class of Stock [Line Items]                  
Warrants to purchase shares of Common Stock | shares 100,000 475,000              
Exercise price of warrants | $ / shares   $ 3.90              
Dividend Yield | June 4th Purchase Agreement                  
Class of Stock [Line Items]                  
Measurement input       0.0          
Dividend Yield | June 8th Purchase Agreement                  
Class of Stock [Line Items]                  
Measurement input       0.0          
Dividend Yield | April 2020 public offering                  
Class of Stock [Line Items]                  
Measurement input   0.00              
Dividend Yield | March 2020 Warrant                  
Class of Stock [Line Items]                  
Measurement input     0.0            
Dividend Yield | April 2020 Maxim Warrant                  
Class of Stock [Line Items]                  
Measurement input   0              
Volatility | June 4th Purchase Agreement                  
Class of Stock [Line Items]                  
Measurement input       64.0          
Volatility | June 8th Purchase Agreement                  
Class of Stock [Line Items]                  
Measurement input       64.0          
Volatility | April 2020 public offering                  
Class of Stock [Line Items]                  
Measurement input   64.00              
Volatility | March 2020 Warrant                  
Class of Stock [Line Items]                  
Measurement input     61.0            
Volatility | April 2020 Maxim Warrant                  
Class of Stock [Line Items]                  
Measurement input   64              
Risk-free rate of interest | June 4th Purchase Agreement                  
Class of Stock [Line Items]                  
Measurement input       0.45          
Risk-free rate of interest | June 8th Purchase Agreement                  
Class of Stock [Line Items]                  
Measurement input       0.32          
Risk-free rate of interest | April 2020 public offering                  
Class of Stock [Line Items]                  
Measurement input   0.37              
Risk-free rate of interest | March 2020 Warrant                  
Class of Stock [Line Items]                  
Measurement input     0.38            
Risk-free rate of interest | April 2020 Maxim Warrant                  
Class of Stock [Line Items]                  
Measurement input   0.37              
Term (Years) | June 4th Purchase Agreement                  
Class of Stock [Line Items]                  
Fair Value Expected Term       5 years 6 months          
Term (Years) | June 8th Purchase Agreement                  
Class of Stock [Line Items]                  
Fair Value Expected Term       5 years 6 months          
Term (Years) | April 2020 public offering                  
Class of Stock [Line Items]                  
Fair Value Expected Term   5 years              
Term (Years) | April 2020 Maxim Warrant                  
Class of Stock [Line Items]                  
Fair Value Expected Term   5 years