Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows From Operating Activities:
Net loss	$ (16,851)	$ (15,371)	$ (20,278)
Adjustments to reconcile net loss to net cash and cash equivalents used in operating activities:
Depreciation and amortization	1,203	1,048	880
Loss (gain) on disposal of assets, net	505	(2)	6
Provision (recovery) for bad debts, net	40	(118)	86
Provision for inventory excess and obsolescence	623	272	647
Provision for sales returns allowance			100
Stock-based compensation	2,207	3,065	3,350
Deferred income taxes	(694)	60	61
Earned interest income, net	(42)	(70)	(74)
Changes in operating assets and liabilities:
Restricted cash		(51)	(200)
Accounts receivable	(337)	(644)	(52)
Inventory	419	(1,989)	(705)
Prepaid expenses and other current assets	(11)	79	(65)
Customer deposits	(74)	16	(27)
Accounts payable and accrued liabilities	(5,003)	3,322	(640)
Accrued legal settlement			(1,664)
Deferred revenue	(397)	(264)	803
Net cash and cash equivalents used in operating activities	(18,412)	(10,647)	(17,772)
Cash Flows From Investing Activities:
Purchases of property, plant, and equipment	(747)	(1,414)	(1,803)
Proceeds from disposal of property, plant, and equipment			25
Net cash and cash equivalents used in investing activities	(747)	(1,414)	(1,778)
Cash Flows From Financing Activities:
Principal payments under capital lease obligation	(146)	(171)	(107)
Proceeds from equity offerings, net of expenses	21,761	9,520
Deposit on capital lease			(42)
Proceeds from exercise of stock options	3	1	44
Net cash and cash equivalents provided by (used in) financing activities	21,618	9,350	(105)
Effect of exchange rate changes	262	(64)	(206)
Increase (decrease) in cash and cash equivalents	2,721	(2,775)	(19,861)
Cash and cash equivalents, beginning of year	8,924	11,699	31,560
Cash and cash equivalents, end of year	11,645	8,924	11,699
Supplemental cash flow disclosure - Cash Paid:
Interest paid	1	4	4
Income taxes paid	164	76	57
Supplemental cash flow disclosure - Non-cash:
Assets acquired under capital lease			378
Accrued capital expenditures and tenant improvement allowance	$ 102	$ 251	$ 1,137