Stock options and warrants (Schedule of Stock-based Compensation) (Details) - USD ($) |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2015 |
Jun. 30, 2014 |
Jun. 30, 2015 |
Jun. 30, 2014 |
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| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Stock-based compensation | $ 347,581 | $ 326,392 | $ 780,983 | $ 729,413 |
| Selling, general and administrative expenses [Member] | ||||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Stock-based compensation | 303,644 | 305,351 | 696,006 | 688,345 |
| Research and development expenses [Member] | ||||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Stock-based compensation | $ 43,937 | $ 21,041 | $ 84,977 | $ 41,068 |
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- Definition Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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