CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (3,780)	$ (2,580)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Provision for doubtful accounts	41
Depreciation and amortization	143	185
Stock-based compensation	257	263
Impairment of goodwill		420
Accrued interest	243	220
Loss on disposal of assets	4
Amortization of lease right-of-use asset	212	212
Change in operating lease liability	(220)	(219)
Other	(1)	(6)
Changes in assets and liabilities
Accounts receivable	433	447
Inventories	369	180
Prepaid expenses and other assets	(135)	416
Accounts payable	(142)	(18)
Deferred revenue and other liabilities	(15)	(171)
Net cash used in operating activities	(2,591)	(651)
Cash flows from investing activities:
Purchases of property and equipment	(71)	(103)
Proceeds from maturities of marketable securities and investments	300	1,275
Purchases of marketable securities and investments		(1,568)
Net cash provided by (used in) investing activities	229	(396)
Cash flows from financing activities:
Proceeds from sale of common stock and warrants, net of issuance costs	1,619
Net proceeds from exercise of pre-funded warrants	2
Taxes paid to net share settle equity awards	(2)	(4)
Net cash provided by (used in) financing activities	2,198	(4)
Net decrease in cash and cash equivalents	(164)	(1,051)
Cash and cash equivalents at beginning of year	6,053	7,104
Cash and cash equivalents at end of year	5,889	6,053
Supplemental disclosure:
Cash paid for income taxes	2	2
Noncash investing and financing activities:
Issuance of convertible notes in settlement of accrued interest	234	$ 187
Fair value of warrant exercise price adjustment considered as deemed dividend	392
PPP Note
Cash flows from financing activities:
Proceeds from PPP note	$ 579