Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (5,886,000)	$ (5,791,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Provision for doubtful accounts	(1,000)	65,000
Depreciation and amortization	204,000	328,000
Stock-based compensation	960,000	810,000
Non-cash interest expense	161,000	142,000
Loss from investment in unconsolidated limited liability company	122,000	76,000
Loss on disposal of property and equipment	1,000	9,000
Modification of warrants	(0)	287,000
Changes in assets and liabilities:
Accounts receivable	41,000	369,000
Inventory	(33,000)	396,000
Prepaid expenses and other current assets	(338,000)	253,000
Other assets	112,000	150,000
Accounts payable	122,000	276,000
Accrued liabilities	311,000	(727,000)
Other noncurrent liabilities	(863,000)	104,000
Net cash used in operating activities	(5,087,000)	(3,253,000)
Cash flows from investing activities:
Purchase of property and equipment	(49,000)	(85,000)
Net cash used in investing activities	(49,000)	(85,000)
Cash flows from financing activities:
Proceeds from January 2021 Offering, net of issuance costs	0	25,122,000
Proceeds from exercise of common warrants	0	179,000
Proceeds from issuance of common shares from employee stock purchase plan	19,000	0
Net cash provided by financing activities	19,000	25,261,000
Net increase (decrease) in cash and cash equivalents	(5,117,000)	21,923,000
Cash and cash equivalents - beginning of period	19,162,000	6,523,000
Cash and cash equivalents - end of period	14,045,000	28,446,000
Supplemental disclosure:
Cash paid for interest	0	0
Cash paid for income taxes	0	0
Supplemental disclosure of cash flow information as of end of period:
Issuance of Series B convertible preferred stock in settlement of dividends	1,263,000	1,118,000
Issuance of note payable in settlement of accrued interest	160,000	141,000
Net transfer of equipment between inventory and property and equipment	(47,000)	(191,000)
Operating cash outflows from operating leases	69,000	75,000
Purchase Agreement with LPC [Member]
Cash flows from financing activities:
Transaction costs	$ 0	$ (40,000)