Balance Sheets - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 3,686,302	$ 8,501,392
Accounts receivable, net of allowance of $361,350 and $379,817 in 2017 and 2016, respectively	4,287,255	4,665,959
Inventories, net	1,146,971	5,381,103
Prepaid expenses and other current assets	750,085	855,295
Total current assets	9,870,613	19,403,749
Property and equipment, net	592,688	1,086,244
Intangible assets, net	159,470	436,569
Other assets	44,432	39,241
Total assets	10,667,203	20,965,803
Current liabilities:
Accounts payable	1,654,101	2,623,010
Accrued liabilities	3,195,247	4,491,164
Deferred revenue	5,702,769	8,751,336
Warrants	19,574,977	19,787,007
Total current liabilities	30,127,094	35,652,517
Long-term deferred revenue	611,863	522,329
Other liabilities	535,369	320,409
Total liabilities	31,274,326	36,495,255
Convertible Preferred stock:
Convertible Preferred stock, par value $0.001; 10,000,000 shares authorized, 23,900 shares outstanding at 2017 and 2016	5,960,475	5,960,475
Stockholders' deficit:
Common stock, par value $0.001; 300,000,000 shares authorized, 22,805,731 and 22,063,582 shares issued at 2017 and 2016, respectively	22,806	22,064
Additional paid in capital	450,748,403	449,939,406
Treasury stock, 4,015 shares at 2017 and 2016	(205,999)	(205,999)
Accumulated deficit	(477,132,808)	(471,245,398)
Total stockholders' deficit	(26,567,598)	(21,489,927)
Total liabilities and stockholders' deficit	$ 10,667,203	$ 20,965,803