Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash Flows From Operating Activities:
Net loss	$ (10,217)	$ (13,228)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	380	219
Restructuring and other costs	0	747
Gain on sale of assets	0	(11)
Warranty provision	45	10
Non-cash lease expense	49	46
Share-based compensation	1,756	3,007
Common shares issued for services	0	239
Provision for doubtful accounts	8	46
Changes in assets and liabilities:
Accounts receivable	2,446	(798)
Inventories	(467)	(713)
Prepaid expenses and other current assets	168	(65)
Accounts payable	(417)	48
Operating lease liability	(41)	(48)
Customer deposits	(39)	8
Accrued liabilities and other	106	53
Warranty settlement	(63)	16
Deferred revenue	79	170
Net cash used in operating activities	(6,207)	(10,254)
Cash Flows From Investing Activities:
Purchase of short-term investments	(14,890)	(25,009)
Proceeds from maturities of short-term investments	20,000	20,000
Capital expenditures for property and equipment	(168)	(367)
Investment in long-term deposits	(2)	0
Proceeds from long-term deposits	0	3
Net cash provided by (used in) investing activities	4,838	(5,469)
Cash Flows From Financing Activities:
Proceeds from exercise of warrants	0	12,048
Proceeds from exercise of stock options	75	278
Repayment of debt	0	(200)
Net cash provided by financing activities	75	12,126
Net decrease in cash and cash equivalents	(1,294)	(3,597)
Cash and cash equivalents, beginning of period	4,937	16,647
Cash and cash equivalents, end of period	3,643	13,050
Supplemental Disclosure of Non-Cash Investing
Change in unrealized gain on short-term investments	(11)	(2)
Right-of-use asset and liability recorded during period	335	0
Patents and Trademarks [Member]
Cash Flows From Investing Activities:
Payments for intangible assets	$ (102)	$ (96)