Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 21,446	$ 20,994
Accounts receivable, net of allowances of $115 and $37 at December 31, 2017 and 2016, respectively	4,734	6,573
Inventories	6,326	5,621
Prepaid expenses and other current assets	3,467	1,539
Total current assets	35,973	34,727
Property and equipment, net	15,229	13,366
Intangible assets, net	744	969
Goodwill	9,123	8,342
Other assets	151	167
Total assets	61,220	57,571
Liabilities, contingently redeemable preferred stock, and stockholders’ equity
Accounts payable	4,038	3,893
Accrued expenses and other	5,615	5,271
Deferred revenue	6,141	5,624
Current portion of long-term debt	546	204
Total current liabilities	16,340	14,992
Long-term debt, net of current portion	3,253	2,203
Other non-current liabilities	115	56
Total liabilities	19,708	17,251
Commitments and contingencies (Note 8)
Contingently redeemable series C preferred stock, 0 and 0.55 shares issued and outstanding at December 31, 2017 and 2016, respectively (liquidation preference of $0 and $550 as of December 31, 2017 and 2016, respectively)		550
Stockholders’ equity:
Preferred stock, $0.01 par value; 1,000 shares authorized Series B convertible preferred stock, 0 and 0.13 shares issued and outstanding at December 31, 2017 and 2016, respectively (liquidation preference of $0 and $13 as of December 31, 2017 and 2016, respectively)
Common stock $0.01 par value; 150,000 shares authorized; 12,257 issued and 10,844 outstanding at December 31, 2017 and 2016, respectively	123	123
Additional paid-in capital	292,108	290,636
Treasury stock (at cost), 1,413 shares at December 31, 2017 and 2016, respectively	(8,601)	(8,601)
Accumulated deficit	(238,961)	(237,360)
Accumulated other comprehensive loss	(3,157)	(5,028)
Total stockholders’ equity	41,512	39,770
Total liabilities, contingently redeemable preferred stock, and Stockholders’ equity	$ 61,220	$ 57,571