Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net loss	$ (4,735,917)	$ (7,656,110)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	535,695	535,819
Depreciation and amortization	493,675	413,545
Amortization of premiums and discounts		3,225
Changes in operating assets and liabilities:
Accounts receivable	1,189,953	(37,737)
Inventories	(1,525,424)	454,348
Prepaid expenses and other assets	(143,668)	120,544
Deferred costs	61,307	(850,113)
Accounts payable	1,138,856	1,714,501
Accrued expenses and other current liabilities	1,225,433	1,249,595
Deferred revenue	(2,221,556)	88,577
Net cash used in operating activities	(3,981,646)	(3,963,806)
Cash flows from investing activities:
Purchases of equipment, molds, furniture and fixtures	(427,257)	(1,766,979)
Additions to patent rights	(8,605)	(32,517)
Proceeds from maturities of investment securities		3,000,000
Net cash provided by (used in) investing activities	(435,862)	1,200,504
Cash flows from financing activities:
Proceeds from exercise of stock options	380,983
Taxes paid related to net share settlement of equity awards		(34,476)
Net cash provided by (used in) financing activities	380,983	(34,476)
Effect of exchange rate changes on cash	(952)	1,246
Net decrease in cash	(4,037,477)	(2,796,532)
Cash and cash equivalents:
Beginning of period	27,714,588	32,898,676
End of period	23,677,111	30,102,144
Supplemental disclosure of non-cash investing activities:
Purchases of equipment, molds, furniture and fixtures recorded in accounts payable and accrued expenses	94,156	1,505,273
Additions to patent rights recorded in accounts payable and accrued expenses	$ 48,365	$ 6,501