Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 28, 2019	Sep. 29, 2018
Operating activities:
Net loss	$ (7,252)	$ (9,957)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	518	617
Change in fair value of earn-out liability	47	94
Stock-based compensation	1,398	1,516
Provision for doubtful accounts	25
Changes in operating assets and liabilities:
Accounts receivable	265	(567)
Inventories	(188)	533
Prepaid expenses and other current assets	(43)	8
Other long-term assets	11	(73)
Accounts payable	(86)	828
Accrued compensation	(1,015)	(175)
Accrued expenses	(726)	335
Accrued warranty	(347)	(903)
Deferred revenue	(331)	(303)
Other long-term liabilities		73
Net cash used in operating activities	(7,724)	(7,974)
Investing activities:
Acquisition of property and equipment	(125)	(391)
Payment on earn-out liability	(318)	(302)
Net cash used in investing activities	(443)	(693)
Financing activities:
Proceeds from issuance of common stock, net of issuance costs		10,637
Proceeds from stock option exercises		97
Taxes paid related to net share settlements of equity awards	(151)	(176)
Net cash (used in) provided by financing activities	(151)	10,558
Effect of foreign exchange rate changes	72	127
Net (decrease) increase in cash and cash equivalents	(8,246)	2,018
Cash and cash equivalents, beginning of period	21,194	21,707
Cash and cash equivalents, end of period	12,948	23,725
Supplemental disclosure of cash flow information:
Cash paid during the period for income taxes	19	9
Supplemental disclosure of non-cash activities:
Transfer of inventory to property and equipment	$ 65	$ 123