Condensed Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash Flows From Operating Activities:
Net loss	$ (5,429)	$ (2,346)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	104	25
Gain on sale of assets	(1)	0
Warranty provision	(2)	14
Non-cash lease expense	25	30
Share-based compensation	859	467
Common shares issued for services	100	0
Provision for doubtful accounts	0	10
Changes in assets and liabilities:
Accounts receivable	(341)	(198)
Inventories	(924)	(44)
Prepaid expenses and other current assets	(9)	(94)
Accounts payable	1,168	43
Operating lease liability	(26)	(31)
Customer deposits	3	(149)
Accrued liabilities and other	(136)	35
Warranty settlement	9	0
Deferred revenue	156	0
Net cash used in operating activities	(4,444)	(2,238)
Cash Flows From Investing Activities:
Purchase of short-term investments	(25,003)	0
Proceeds from maturities of short-term investments	15,000	0
Capital expenditures for property and equipment	(160)	(20)
Investment in patents and trademarks	(56)	(34)
Proceeds from long-term deposits	3	0
Net cash used in investing activities	(10,216)	(54)
Cash Flows From Financing Activities:
Proceeds from exercise of warrants	0	632
Proceeds from exercise of stock options	113	169
Repayment of debt	(100)	0
Net cash provided by financing activities	13	801
Net decrease in cash and cash equivalents	(14,647)	(1,491)
Cash and cash equivalents, beginning of period	16,647	16,984
Cash and cash equivalents, end of period	$ 2,000	$ 15,493