Consolidated Balance Sheets - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 19,162,000	$ 6,523,000	[1]
Accounts receivable, net of allowance for doubtful accounts of $66 and $124 as of December 31, 2021 and 2020, respectively	549,000	770,000	[1]
Inventory	1,472,000	3,254,000	[1]
Prepaid expenses and other current assets	1,055,000	1,031,000	[1]
Total current assets	22,238,000	11,578,000	[1]
Property and equipment, net	1,554,000	2,759,000	[1]
Investment in limited liability company	577,000	833,000	[1]
Other assets	1,544,000	1,460,000	[1]
Total assets	25,913,000	16,630,000	[1]
Current liabilities:
Accounts payable	1,480,000	881,000	[1]
Accrued liabilities	3,053,000	2,416,000	[1]
Paycheck Protection Program loan, current portion	0	918,000	[1]
Total current liabilities	4,533,000	4,215,000	[1]
Note payable, noncurrent portion	5,124,000	4,518,000	[1]
Paycheck Protection Program loan, noncurrent portion	0	425,000	[1]
Other noncurrent liabilities	1,190,000	498,000	[1]
Total liabilities	10,847,000	9,656,000	[1]
Commitments and contingences (Note 10)
Stockholders’ equity:
Common stock, $0.0001 par value; 75,000,000 shares authorized as of December 31, 2021 and 2020; 10,619,846 and 2,171,316 shares issued and outstanding as of December 31, 2021 and 2020, respectively	1,000	0
Additional paid-in capital	256,918,000	226,800,000	[1]
Accumulated deficit	(241,853,000)	(219,826,000)	[1]
Total stockholders’ equity	15,066,000	6,974,000	[1]
Total liabilities and stockholders’ equity	25,913,000	16,630,000	[1]
Series B Preferred Stock [Member]
Stockholders’ equity:
Convertible preferred stock	0	0
Series C Preferred Stock [Member]
Stockholders’ equity:
Convertible preferred stock	$ 0	$ 0

[1] The condensed consolidated balance sheet as of December 31, 2020 has been derived from the audited consolidated financial statements as of that date.