Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 49,536	$ 60,033
Accounts receivable, net of allowance for doubtful accounts of $22 and $5, respectively	14	28
Inventory	476	597
Prepaid expenses and other current assets	706	1,202
Total current assets	50,732	61,860
Property and equipment, net of accumulated depreciation of $911 and $735, respectively	1,736	1,701
Intangible assets, net of accumulated amortization of $1,378 and $1,102, respectively	4,962	5,238
Other assets	1	215
Total assets	57,431	69,014
Current liabilities:
Accounts payable	1,368	2,958
Accrued expenses	1,600	487
Deferred revenue	280	148
Total current liabilities	3,248	3,593
Warrant liability	14,258	15,216
Other long term liabilities	632	539
Total liabilities	18,138	19,348
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares outstanding
Common stock, $0.001 par value; 100,000,000 shares authorized; 40,856,815 and 39,832,225 shares issued and outstanding, respectively	41	40
Additional paid-in capital	142,586	136,694
Accumulated deficit	(103,334)	(87,068)
Total stockholders' equity	39,293	49,666
Total liabilities and stockholders' equity	$ 57,431	$ 69,014