Intangible assets other than goodwill -Amounts related to intangible assets (Details) - USD ($) |
Mar. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Finite-Lived Intangible Assets [Line Items] | ||
| Intangible assets | $ 1,391,265 | $ 1,363,306 |
| Less - accumulated amortization | (342,985) | (318,695) |
| Intangible assets, net | 1,048,280 | 1,044,611 |
| Product Certifications | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Intangible assets | 514,616 | 514,616 |
| Less - accumulated amortization | (195,681) | (182,931) |
| Intangible assets, net | 318,935 | 331,685 |
| Patents | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Intangible assets | 631,024 | 603,915 |
| Less - accumulated amortization | (99,304) | (91,764) |
| Intangible assets, net | 531,720 | 512,151 |
| Developed Technology | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Intangible assets | 240,000 | 240,000 |
| Less - accumulated amortization | (48,000) | (44,000) |
| Intangible assets, net | 192,000 | 196,000 |
| Trademarks | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Intangible assets | 5,625 | 4,775 |
| Intangible assets, net | $ 5,625 | $ 4,775 |