Amortizable intangible assets -Amounts related to intangible assets (Details) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 1,325,359	$ 1,230,274
Finite-Lived Intangible Assets, Accumulated Amortization	(270,393)	(218,974)
Finite-Lived Intangible Assets, Net	1,054,966	1,011,300
Intangible Assets, Current	1,054,966
Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	577,232	514,930
Finite-Lived Intangible Assets, Accumulated Amortization	(76,775)	(62,242)
Finite-Lived Intangible Assets, Net		452,688
Intangible Assets, Current	500,457
Product Certification [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	508,127	475,344
Finite-Lived Intangible Assets, Accumulated Amortization	(157,618)	(128,732)
Finite-Lived Intangible Assets, Net		346,612
Intangible Assets, Current	350,509
Developed Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	240,000	240,000
Finite-Lived Intangible Assets, Accumulated Amortization	(36,000)	(28,000)
Finite-Lived Intangible Assets, Net		$ 212,000
Intangible Assets, Current	$ 204,000