Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (11,769,000)	$ (17,128,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	527,000	513,000
Amortization	61,000	33,000
Noncash stock-based compensation	764,000	742,000
Noncash interest	419,000	437,000
Changes in operating assets and liabilities:
Accounts receivable	(132,000)	543,000
Income taxes receivable	(4,675,000)
Inventory	(1,727,000)	(1,590,000)
Prepaid expenses and other assets	707,000	421,000
Accounts payable and accrued expenses	1,095,000	1,393,000
Lease liability	(21,000)	(32,000)
Net cash used in operating activities	(14,751,000)	(14,668,000)
Cash flows from investing activities:
Sales and maturities of marketable securities		16,256,000
Acquisition of property and equipment	(126,000)	(71,000)
Net cash (used in) provided by investing activities	(126,000)	16,185,000
Cash flows from financing activities:
Repayment of long-term debt	(5,000,000)
Proceeds from exercise of stock options		75,000
Net cash (used in) provided by financing activities	(523,000)	484,000
Net increase (decrease) in cash and cash equivalents	(15,400,000)	2,001,000
Cash and cash equivalents, beginning of period	19,143,000	14,463,000
Cash and cash equivalents, end of period	3,743,000	16,464,000
Supplemental disclosure of noncash financing activities
Warrants issued in connection with long-term debt		1,080,000
Warrants issued in connection with preferred stock offering	2,101,000
Conversion of Series A preferred stock into common stock	897,000
Supplemental cash flow information
Interest paid	452,000	588,000
Public offering
Cash flows from financing activities:
Proceeds from issuance of preferred stock in registered direct offering, net of offering costs	4,129,000
At-the-market sales
Cash flows from financing activities:
Proceeds from At-the-Market sales of common stock, net of offering costs	$ 348,000	$ 409,000