Balance Sheets - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 5,739,124	$ 8,501,392
Accounts receivable, net of allowance of $600,567 and $379,817 in 2017 and 2016, respectively	5,316,935	4,665,959
Inventories	5,658,369	5,381,103
Prepaid expenses and other current assets	911,829	855,295
Total current assets	17,626,257	19,403,749
Property and equipment, net	935,095	1,086,244
Intangible assets, net	386,738	436,569
Other assets	41,394	39,241
Total assets	18,989,484	20,965,803
Current liabilities:
Accounts payable	2,215,111	2,623,010
Accrued liabilities	4,085,696	4,491,164
Deferred revenue	9,374,879	8,751,336
Warrants	16,657,699	19,787,007
Total current liabilities	32,333,385	35,652,517
Long-term deferred revenue	435,542	522,329
Other liabilities	320,545	320,409
Total liabilities	33,089,472	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, 22,545,128 and 22,063,582 shares issued at 2017 and 2016, respectively	22,545	22,064
Additional paid in capital	450,191,422	449,939,406
Treasury stock, 4,015 shares at 2017 and 2016	(205,999)	(205,999)
Accumulated deficit	(470,068,431)	(471,245,398)
Total stockholders' deficit	(20,060,463)	(21,489,927)
Total liabilities and stockholders' deficit	$ 18,989,484	$ 20,965,803