Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 26,850	$ 37,495
Accounts receivable, net of allowance for doubtful accounts of $16 and $17, respectively	3	4
Inventory	484	571
Prepaid expenses and other current assets	730	1,279
Total current assets	28,067	39,349
Property and equipment, net of accumulated depreciation of $1,121 and $1,051, respectively	1,639	1,598
Intangible assets, net of accumulated amortization of $1,929 and $1,653, respectively	4,411	4,687
Total assets	34,117	45,634
Current liabilities:
Accounts payable	1,957	1,124
Accrued expenses	2,113	1,675
Deferred revenue	500	416
Warrant liability, current	650	278
Total current liabilities	5,220	3,493
Warrant liability, long term	11,697	11,008
Other long term liabilities	773	724
Total liabilities	17,690	15,225
Stockholders’ equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares outstanding	0	0
Common stock, $0.001 par value; 100,000,000 shares authorized; 40,913,065 and 40,856,815 shares issued and outstanding, respectively	41	41
Additional paid-in capital	144,385	143,086
Accumulated deficit	(127,999)	(112,718)
Total stockholders’ equity	16,427	30,409
Total liabilities and stockholders’ equity	$ 34,117	$ 45,634