Condensed Balance Sheets - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 93,602,000	$ 110,231,000
Short-term investments	0	0
Accounts receivable, net	13,876,000	11,832,000
Inventories	17,726,000	17,851,000
Prepaid expenses and other current assets	2,564,000	3,412,000
Total current assets	127,768,000	143,326,000
Property and equipment, net	9,866,000	7,697,000
Restricted cash	232,000	232,000
Other non-current assets	5,134,000	5,370,000
Total assets	143,000,000	156,625,000
Current liabilities:
Accounts payable	2,926,000	2,379,000
Accrued liabilities	16,744,000	19,802,000
Short-term debt	9,829,000	3,905,000
Total current liabilities	29,499,000	26,086,000
Long-term debt	38,901,000	44,786,000
Other liabilities	6,893,000	6,513,000
Total liabilities	75,293,000	77,385,000
Commitments and contingencies (Note 7)
Stockholders’ equity):
Preferred stock, $0.001 par value Shares authorized: 5,000,000 at March 31, 2022 and December 31, 2021 Shares issued and outstanding: none at March 31, 2022 and December 31, 2021
Common stock, $0.001 par value Shares authorized: 100,000,000 at March 31, 2022 and December 31, 2021 Shares issued and outstanding: 35,073,602 and 34,980,896 at March 31, 2022 and December 31, 2021, respectively	35,000	35,000
Additional paid-in capital	373,053,000	367,907,000
Accumulated deficit	(305,381,000)	(288,702,000)
Total stockholders’ equity	67,707,000	79,240,000
Total liabilities and stockholders’ equity	$ 143,000,000	$ 156,625,000