Annual report pursuant to Section 13 and 15(d)

Stock options, warrants and restricted common stock (Stock Incentive Plan Options) (Narrative) (Details)

v3.19.1
Stock options, warrants and restricted common stock (Stock Incentive Plan Options) (Narrative) (Details) - USD ($)
 1 Months Ended 12 Months Ended
Dec. 31, 2018
Mar. 31, 2018
Jan. 31, 2018
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Number of shares reserved under the Plan         895,000  
Fair value of options vested         $ 4,654,000  
Proceeds from options exercised       $ 78,522 149,136  
Net proceeds from exercise of stock options       78,522 149,136  
Total stock-based compensation       4,660,406 2,589,812  
Proceeds from exercise of warrants       $ 350,000 $ 1,860,000  
Minimum [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Expiration period         3 years  
Maximum [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Expiration period         5 years  
Stock Options [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Expiration period         10 years  
Restricted common stock [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options granted       431,000 863,000  
Common shares vested       530,065 326,848  
Options grant date fair value       $ 10.46 $ 5.39  
Options forfeited         40,000  
Fair value of options vested         $ 125,000  
Proceeds from options exercised       $ 4,500,000 $ 4,700,000  
Expected to vest         326,848  
Unrecognized compensation cost $ 1,176,000     $ 1,176,000 $ 2,964,000  
Unrecognized compensation cost, period for recognition         1 year  
Rights forfeited         833  
Total stock-based compensation         $ 1,714,116  
Vested rights remaining to be issued       152,766 152,766  
Restricted common stock [Member] | Vested in Period [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Fair value of options vested         $ 1,565,000  
Restricted common stock [Member] | Certain board members and officers [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options granted       418,500 292,500  
Options forfeited       301,148    
Restricted common stock [Member] | Board of Directors [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options granted         863,000  
Vesting period       1 month 6 days    
Options forfeited       7,667 6,251  
Restricted common stock [Member] | Advisory Board member [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options forfeited         20,000  
Restricted common stock [Member] | Directors and Officers [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Common shares vested         326,848  
Issuance of common stock       327,416 174,082  
Restricted common stock [Member] | Consultant [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options granted       12,500    
Restricted common stock [Member] | Employees and officers [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options forfeited       293,481    
Other Options [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options granted         174,082  
Fair value of options vested         $ 1,600,000  
Total stock-based compensation         $ 108,021  
Vested Options [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Shares issued in options exercised     19,533      
Proceeds from options exercised     $ 78,523      
2017 Equity Incentive Plan [Member] | Restricted common stock [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options granted         10,251  
Stock Incentive Plan [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options granted       62,000 120,000  
Common shares vested       0    
Options granted, exercise price       $ 15.71 $ 9.00  
Options grant date fair value       $ 4.25    
Options exercised       19,533 50,800  
Options forfeited       100,000 516,414  
Options forfeited, exercise price       $ 10.00 $ 22.16  
Options forfeited, unvested, exercise price       $ 2.92    
Fair value of options vested         $ 639,000 $ 646,000
Shares issued in options exercised       19,533 50,800  
Proceeds from options exercised       $ 78,522    
Net proceeds from exercise of stock options         $ 149,136  
Total intrinsic value when exercised       51,000 $ 171,000  
Unrecognized compensation cost, period for recognition         1 year  
Total stock-based compensation       $ 58,000    
Stock Incentive Plan [Member] | Directors and Officers [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options granted       62,000 120,000  
Options granted, exercise price       $ 18.50 $ 9.00  
Stock Incentive Plan [Member] | Directors and Officers [Member] | Vesting in Period One [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options granted       50,000 20,000  
Options granted, exercise price       $ 4.09 $ 4.02  
Vesting period         24 months  
Stock Incentive Plan [Member] | Directors and Officers [Member] | Vesting in Period Two [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options granted       12,000 100,000  
Options granted, exercise price       $ 4.09 $ 10.00  
Stock Incentive Plan [Member] | Equity rights terminations [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options forfeited         515,578  
Stock Incentive Plan [Member] | Options terminated [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options forfeited         836  
Stock Incentive Plan [Member] | Vested Options [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options forfeited         459,414 21,859
Options forfeited, exercise price         $ 24.55 $ 40.49
Stock Incentive Plan [Member] | Unvested Options [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options forfeited         57,000 3,620
Options forfeited, unvested, exercise price         $ 2.92 $ 15.13
May 2013 private offering [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Warrants issued for surrendered for issuance of common stock 3,215          
Warrants issued 13,009 100,000        
Proceeds from exercise of warrants $ 350,000          
Warrant forfeited 160,773