Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 146,205,071	$ 5,026,523
Accounts receivable	16,094,788	4,699,730
Inventory	24,735,601	10,406,320
Prepaid expenses and other current assets	5,709,766	1,850,859
Total current assets	192,745,226	21,983,432
Restricted cash	500,000	500,000
Property, plant, and equipment, net	5,311,907	5,277,667
Leased property under capital lease, net	1,936,826	2,453,312
Note receivable	447,408	509,945
Intangible assets, net	1,490,319	2,901,595
Other assets	3,448,974	1,729,670
Total assets	205,880,660	35,355,621
Current liabilities:
Accounts payable	10,185,085	3,094,385
Accrued expenses	8,749,356	3,068,774
Product warranty reserve	1,311,442	1,608,131
Deferred revenue	3,318,919	1,705,065
Obligations under capital lease	586,879	717,870
Other current liabilities	1,554,960	679,176
Total current liabilities	25,706,641	10,873,401
Obligations under capital lease		586,879
Deferred revenue	8,501,404	7,308,951
Common stock warrant liability	9,418,413	28,829,849
Finance obligation	2,426,028	2,492,330
Other liabilities	392,335	765,281
Total liabilities	46,444,821	50,856,691
Redeemable preferred stock
Series C redeemable convertible preferred stock, $0.01 par value per share (aggregate involuntary liquidation preference $16,663,782) 10,431 shares authorized; Issued and outstanding: 5,231 at December 31, 2014 and 10,431 at December 31, 2013	1,152,720	2,371,080
Stockholders' equity (deficit):
Common stock, $0.01 par value per share; 450,000,000 shares authorized; Issued (including shares in treasury): 173,644,532 at December 31, 2014 and 106,356,558 at December 31, 2013	1,736,445	1,063,566
Additional paid-in capital	1,096,391,668	831,155,925
Accumulated other comprehensive income	897,807	897,807
Accumulated deficit	(938,080,766)	(849,437,066)
Less common stock in treasury: 378,116 shares at December 31, 2014 and 165,906 at December 31, 2013	(2,662,035)	(1,552,382)
Total stockholders' equity (deficit)	158,283,119	(17,872,150)
Total liabilities, redeemable preferred stock, and stockholders' equity (deficit)	$ 205,880,660	$ 35,355,621