Annual report pursuant to Section 13 and 15(d)

Summary of significant accounting policies - Additional Information (Details)

v3.3.1.900
Summary of significant accounting policies - Additional Information (Details) - USD ($)
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Jul. 22, 2013
Debt Instrument [Line Items]      
Allowance for doubtful accounts $ 50,000 $ 50,000  
Bill and Hold Transactions 928,900 1,020,000  
Advertising expense 183,512 281,330  
Research and development costs reimbursed by government agencies 0 74,800  
Research and development $ 591,585 $ 1,116,283  
Revolving credit facility | Chief Executive Officer (John N. Hatsopoulos)      
Debt Instrument [Line Items]      
Bank credit facility     $ 1,055,000