BALANCE SHEET COMPONENTS (Tables)

6 Months Ended

Jun. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of accounts receivable, net and activity in allowance for uncollectible accounts

Accounts receivable, net consisted of the following (in thousands):

	June 30, 2023		December 31, 2022
Accounts receivable	$	48	$	119
Allowance for uncollectible accounts	(4)		(6)
Accounts receivable, net	$	44	$	113

The following was the activity in the allowance for uncollectible accounts (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Balance as of beginning of period	$	4	$	—	$	6	$	—
Increase in provision	—		12		—		12
Amounts written off, less recoveries	—		—		(2)		—
Balance as of end of period	$	4	$	12	$	4	$	12

Schedule of inventory, net and activity in reserve for obsolescence

Inventory, net consisted of the following (in thousands):

	June 30, 2023		December 31, 2022
Raw materials	$	729	$	772
Finished goods	54		99
Total inventory	783		871
Less: reserve for obsolescence	(18)		(18)
Inventory, net	$	765	$	853

The following was the activity in the reserve for obsolescence (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Balance as of beginning of period	$	18	$	26	$	18	$	29
Increase in reserve	—		—		—		—
Amounts relieved	—		(4)		—		(7)
Balance as of end of period	$	18	$	22	$	18	$	22

Schedule of prepaid expenses

Prepaid expenses consisted of the following (in thousands):

	June 30, 2023		December 31, 2022
Professional services	$	107	$	41
Insurance	97		61
Software licenses	94		157
Other	14		6
Patents	10		39
Marketing programs and conferences	8		74
Total prepaid expenses	$	330	$	378

Schedule of property and equipment, net

Property and equipment, net consisted of the following (in thousands):

	June 30, 2023		December 31, 2022
Research and development equipment	$	1,569	$	1,558
Office and computer equipment	803		800
Autos	54		54
Furniture and fixtures	41		41
Leasehold improvements	119		119
Total in service	2,586		2,572
Accumulated depreciation and amortization	(2,353)		(2,283)
Total in service, net	233		289
Construction in progress	12		5
Property and equipment, net	$	245	$	294

Schedule of accrued expenses

Accrued expenses consisted of the following (in thousands):

	June 30, 2023		December 31, 2022
Compensation, severance and related benefits	$	468	$	497
Legal services	138		36
Product warranty	15		18
Personal property and franchise tax	—		6
Other	—		3
Total accrued expenses	$	621	$	560