Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities:
Net income (loss)	$ (3,227)	$ (3,663)
Reconciliation of net loss to net cash provided by operating activities:
Depreciation and amortization	1,668	1,435
Stock-based compensation expense	1,216	804
Changes in operating assets and liabilities:
Accounts receivable	356	1,680
Inventories	(274)	(1,215)
Prepaid expenses and other current assets	(550)	282
Other non-current assets	88	18
Accounts payable	897	2,836
Accrued expenses and other	298	354
Deferred revenue	1,761	1,149
Net cash provided by operating activities	2,233	3,680
Investing activities:
Purchases of property and equipment	(2,404)	(2,256)
Net cash used in investing activities	(2,404)	(2,256)
Financing activities:
Proceeds from loan facility	954
Proceeds from equipment loans	1,501
Principal payments on debt	(1,269)	(175)
Dividends paid	(14)	(21)
Net cash provided by (used in) financing activities	1,172	(196)
Effect of exchange rate changes on cash and cash equivalents	111	(158)
Net increase in cash and cash equivalents	1,112	1,070
Cash and cash equivalents, beginning of period	20,994	13,901
Cash and cash equivalents, end of period	22,106	14,971
Supplemental cash flow information
Cash paid for interest	85	$ 67
Supplemental noncash information
Purchases of equipment through accounts payable and accrued expenses	100
Series C Preferred Stock [Member]
Supplemental noncash information
Excess of carrying value of Series C Preferred Stock over redemption value	$ 459