Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017
Operating activities:
Net loss	$ (9,957)	$ (7,712)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Gain on sale of intellectual property		(175)
Depreciation and amortization	617	660
Change in fair value of earn-out liability	94	122
Stock-based compensation	1,516	1,357
Provision for doubtful accounts		(4)
Changes in operating assets and liabilities:
Accounts receivable	(567)	2,639
Inventories	533	974
Prepaid expenses and other current assets	8	(221)
Other long-term assets	(73)	32
Accounts payable	828	(130)
Accrued compensation	(175)	(8)
Accrued expenses	335	(347)
Accrued warranty	(903)	79
Deferred revenue	(303)	20
Other long-term liabilities	73	80
Net cash used in operating activities	(7,974)	(2,634)
Investing activities:
Acquisition of property and equipment	(391)	(542)
Proceeds from sale of intellectual property		175
Payment on earn-out liability	(302)	(292)
Net cash used in investing activities	(693)	(659)
Financing activities:
Proceeds from issuance of common stock, net of issuance costs	10,637	2,263
Proceeds from stock option exercises	97	328
Taxes paid related to net share settlements of equity awards	(176)	(294)
Net cash provided by financing activities	10,558	2,297
Effect of foreign exchange rate changes	127
Net increase (decrease) in cash and cash equivalents	2,018	(996)
Cash and cash equivalents, beginning of period	21,707	23,747
Cash and cash equivalents, end of period	23,725	22,751
Cash paid during the period for:
Income taxes	9	$ 19
Supplemental disclosure of non-cash activities:
Transfer of inventory to property and equipment	$ 123