Intangible assets other than goodwill -Amounts related to intangible assets (Details) - USD ($) |
Mar. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Finite-Lived Intangible Assets [Line Items] | ||
| Intangible assets | $ 1,536,579 | $ 1,482,971 |
| Less - accumulated amortization | (441,832) | (417,004) |
| Intangible assets, net | 1,094,747 | 1,065,967 |
| Product Certifications | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Intangible assets | 582,166 | 544,651 |
| Less - accumulated amortization | (246,830) | (233,992) |
| Intangible assets, net | 335,336 | 310,659 |
| Patents | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Intangible assets | 696,498 | 681,155 |
| Less - accumulated amortization | (131,002) | (123,012) |
| Intangible assets, net | 565,496 | 558,143 |
| Developed Technology | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Intangible assets | 240,000 | 240,000 |
| Less - accumulated amortization | (64,000) | (60,000) |
| Intangible assets, net | 176,000 | 180,000 |
| Trademarks | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Intangible assets | 17,915 | 17,165 |
| Intangible assets, net | $ 17,915 | $ 17,165 |