BALANCE SHEET COMPONENTS (Tables)

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

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

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

	As of December 31,
	2023		2022
Accounts receivable	$	99	$	119
Allowance for uncollectible accounts	(4)		(6)
Accounts receivable, net	$	95	$	113

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

	Years Ended December 31,
	2023		2022
Balance as of beginning of year	$	6	$	—
Increase in provision	2		8
Amounts written off, less recoveries	(4)		(2)
Balance as of end of year	$	4	$	6

Schedule of inventory, net and activity in reserve for obsolescence

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

	As of December 31,
	2023		2022
Raw materials	$	747	$	772
Finished goods	53		99
Total inventory	800		871
Reserve for obsolescence	(5)		(18)
Inventory, net	$	795	$	853

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

	Years Ended December 31,
	2023		2022
Balance as of beginning of year	$	18	$	29
Increase in reserve	—		—
Amounts relieved	(13)		(11)
Balance as of end of year	$	5	$	18

Schedule of prepaid expenses

Prepaid expenses consist of the following (in thousands):

	As of December 31,
	2023		2022
Software licenses	$	152	$	157
Prepaid inventory	111		—
Insurance	64		61
Professional services	30		41
Patents	14		39
Marketing programs and conferences	1		74
Other	16		6
Total prepaid expenses	$	388	$	378

Schedule of property and equipment, net

Depreciation on property and equipment is computed using the straight-line method over the estimated useful lives of the respective assets as follows:

Research and development equipment	5 years
Office and computer equipment	3 years
Autos	5 years
Furniture and fixtures	7 years

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

	As of December 31,
	2023		2022
Research and development equipment	$	1,763	$	1,558
Office and computer equipment	808		800
Autos	54		54
Furniture and fixtures	41		41
Leasehold improvements	141		119
Total in service	2,807		2,572
Accumulated depreciation and amortization	(2,419)		(2,283)
Total in service, net	388		289
Construction in progress	—		5
Property and equipment, net	$	388	$	294

Schedule of accrued expenses

Accrued expenses consist of the following (in thousands):

	As of December 31,
	2023		2022
Compensation, severance and related benefits	$	232	$	497
Legal services	121		36
Product warranty	15		18
Personal property and franchise tax	—		6
Other	—		3
Total accrued expenses	$	368	$	560

Schedule of maturities of notes payable

As of December 31, 2023, future principal payments were as follows (in thousands):

2024	$	33
2025	36
2026	39
2027	43
2028	38
Total principal payments	189
Less: current portion of notes payable	(33)
Notes payable, less current portion	$	156