Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Cash flows for operating activities:
Net loss	$ (12,859,253)	$ (14,913,151)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	262,334	251,327
Stock-based compensation	209,691	225,408
Change in fair value of warrant liability	(208,480)	(275,662)
Changes in operating assets and liabilities:
Accounts receivable	(310,600)	69,096
Inventories	(117,409)	(163,154)
Prepaid expenses and other current and long-term assets	(884,642)	(754,797)
Accounts payable	(8,117)	(267,583)
Accrued expenses and compensation	1,072,297	347,176
Deferred revenue	191,795	401,064
Net cash used in operating activities	(12,652,384)	(15,080,276)
Cash flows for investing activities:
Purchases of fixed assets	(163,096)	(100,499)
Net cash used in investing activities	(163,096)	(100,499)
Cash flows from financing activities:
Net proceeds from issuance of stock and warrants, including private offerings and equity plans	12,910,026	6,667,038
Net cash provided by financing activities	12,910,026	6,667,038
Net (decrease) increase in cash and cash equivalents	94,546	(8,513,737)
Cash and cash equivalents, beginning of year	3,949,135	12,462,872
Cash and cash equivalents, end of year	4,043,681	3,949,135
Supplemental disclosure of cash flow information:
Fixed asset additions included in accounts payable	7,374	0
Change in fair value of warrant liability from repricing	244,611	0
Exchange of warrant liability for Series F Preferred Stock	40,772	0
Common stock issued to settle employee incentive compensation obligation	$ 0	$ 318,761