CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 3,868	$ 8,766
Short-term investments		1,002
Accounts receivable, net	1,681	559
Inventories	1,766	1,451
Prepaid expenses and other	1,347	473
Total current assets	8,662	12,251
Property and equipment, net	827	1,274
Goodwill	13,276	13,276
Intangible assets, net	111	223
Other	263	121
Total assets	23,139	27,145
Current liabilities
Accounts payable	170	561
Deferred revenue	3,938	271
Accrued expenses and other	2,507	2,502
Total current liabilities	6,615	3,334
Long-term liabilities	18	233
Convertible notes payable	9,160	8,250
Total liabilities	15,793	11,817
Commitments and contingencies (Note 9)
Stockholders' equity
Preferred stock, $0.01 par value; 20,000 shares authorized; none issued and outstanding
Common stock, $0.001 par value; 120,000 shares authorized; 8,068 shares and 6,630 shares issued and outstanding at December 31, 2017 and December 31, 2016, respectively	8	7
Additional paid-in capital	232,026	229,341
Accumulated deficit	(224,688)	(214,020)
Total stockholders' equity	7,346	15,328
Total liabilities and stockholders' equity	$ 23,139	$ 27,145