Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net loss	$ (7,886)	$ (5,981)
Adjustments to reconcile net loss to net cash used in operating activities:
Other income - employee retention tax credit	(876)	0
Gain on forgiveness of PPP loan	(801)	0
Depreciation	188	184
Stock-based compensation	429	131
Change in fair value of warrant liabilities	0	1,086
Provision for doubtful accounts receivable	6	(20)
Provision for slow-moving and obsolete inventories	156	(610)
Provision for warranties	68	31
Amortization of loan discounts and origination fees	230	395
Loss on dispositions of property and equipment	0	8
Change in operating assets and liabilities:
Accounts receivable	783	377
Inventories	(2,381)	1,137
Short-term deposits	257	(670)
Prepaid and other assets	669	(18)
Accounts payable	(423)	1,096
Accrued and other liabilities	(380)	349
Deferred revenue	196	54
Total adjustments	(1,879)	3,530
Net cash used in operating activities	(9,765)	(2,451)
Cash flows from investing activities:
Acquisitions of property and equipment	(443)	(223)
Net cash used in investing activities	(443)	(223)
Cash flows from financing activities:
Proceeds from the issuance of common stock and warrants	9,500	2,749
Proceeds from the exercise of warrants	801	918
Offering costs paid on the issuance of common stock and warrants	(969)	(510)
Proceeds from PPP loan	0	795
Proceeds from exercise of stock options and purchases through employee stock purchase plan	80	100
Principal payments under finance lease obligations	(3)	(3)
Common stock withheld in lieu of income tax withholding on vesting of restricted stock units	(1)	(3)
Payments for deferred financing costs & termination fees	(30)	(320)
Payments on the Iliad Note	0	(1,306)
Proceeds from the Streeterville Note	1,515	0
Net cash provided by financing activities	10,712	4,160
Net increase in cash and restricted cash	504	1,486
Cash and restricted cash, beginning of year	2,178	692
Cash and restricted cash, end of year	2,682	2,178
Classification of cash and restricted cash:
Cash	2,682	1,836
Restricted cash held in other assets	0	342
Cash and restricted cash	2,682	2,178
Supplemental information:
Cash paid in year for interest	381	269
Cash paid in year for income taxes	4	4
Austin Credit Facility
Cash flows from financing activities:
Net proceeds from (payment on) credit line borrowings	0	(719)
Credit Facilities
Cash flows from financing activities:
Net proceeds from (payment on) credit line borrowings	$ (181)	$ 2,459