Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Summary of (loss) before income taxes

	Year ended December 31,
	2019			2018
	(in thousands)
U.S.	$	(1,142	)	$	1,017
Foreign		17			(30	)
Total	$	(1,125	)	$	987

Summary of income tax expense (benefit)

	Year ended December 31,
	2019		2018
	(in thousands)
Current
U.S.	$	—	$	—
State		—		—
Foreign		22		24
Total current income tax expense		22		24
Deferred
U.S.		—		—
State		—		—
Foreign		—		—
Total deferred income tax expense (benefit)		—		—
Total income tax expense (benefit)	$	22	$	24

Summary of reconciliation of income tax computed at federal statutory rate to income before taxes

	Year ended December 31,
	2019			2018
U.S. federal statutory rate		(21.0	)%		(21.0	)%
State taxes net of federal benefit		(7.6	)		(7.7	)
Foreign rate differential and transactional tax		0.1			0.1
Tax credits		—			(14.0	)
Valuation allowance		28.5			42.7
Other		2.0			(2.5	)
		2.0	%		(2.4	)%

Summary of significant components of net deferred income taxes

	2019			2018
	(in thousands)
Deferred tax assets:
Allowance for doubtful accounts	$	11		$	2
Inventory reserves		3,185			3,323
Consumables excess reserve		169			170
Accrued liabilities		52			55
Warrant interest expense		196			196
Stock compensation expense		789			881
State net operating loss		15,010			14,633
Net operating loss carryforward		40,437			38,525
Tax credits		740			740
Depreciation		1,329			2,993
Valuation allowance		(61,869	)		(61,512	)
Total deferred tax assets		49			6
Deferred tax liability:
Prepaid expenses		(49	)		(6	)
Net deferred tax liability	$	—		$	—