Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (10,018)	$ (11,908)
Adjustments to reconcile net loss to net cash used in operating activities:
Gain on investments held to maturity		(47)
Depreciation and amortization	413	447
Stock-based compensation	873	3,413
Bad Debt Expense	123
Loss on sale of equipment	3	15
Loss on early extinguishment of debt		10
Loss on change in fair value of derivative		1
(Increase) decrease in current assets:
Accounts receivable - trade	(10)	(123)
Accounts receivable - other	(123)
Other assets	(5)
Prepaid expenses	85	(172)
Inventory	81	(721)
Deposits	(11)	10
Increase (decrease) in current liabilities:
Accounts payable	92	(218)
Accrued expenses	455	189
Deferred rent	(16)	(25)
Net cash used in operating activities	(8,058)	(9,129)
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds received on sale of securities held to maturity		5,070
Proceeds received on sale of equipment		185
Purchase of property and equipment	(71)	(239)
Net cash provided by (used in) investing activities	(71)	5,016
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of common stock, net	3,631	5,132
Proceeds from the issuance of notes payable		9
Repayments of notes payable	(220)	(281)
Repayments of notes payable, related parties		(12)
Repayments of finance lease obligations		(71)
Proceeds from the exercise of warrants	1,789	2,213
Payment of employee withholding taxes related to share-based awards	(55)	(58)
Net cash provided by financing activities	5,145	6,932
NET CHANGE IN CASH	(2,984)	2,819
CASH AT BEGINNING OF PERIOD	4,920	2,101
CASH AT END OF PERIOD	1,936	4,920
SUPPLEMENTAL INFORMATION:
Interest paid	42	74
Income taxes paid
NON-CASH INVESTING AND FINANCING ACTIVITIES:
Common stock warrant revaluation	11
Deemed dividend		333
Purchases of equipment under finance lease obligations		37
Common stock issued on accrued bonus	$ 33