Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
CURRENT ASSETS:
Cash and cash equivalents	$ 20,501	$ 19,064
Marketable securities	53,592	75,135
Accounts receivable, net	123	617
Inventories, net	4,695	4,553
Prepaid and other current assets	3,527	6,181
Total current assets	82,438	105,550
Right-of-use assets	15,152	15,502
Property and equipment, net	7,902	7,665
Restricted cash	2,150	2,150
Other noncurrent assets	2,438	2,473
Total assets	110,080	133,340
CURRENT LIABILITIES:
Accounts payable	2,209	3,218
Accrued expenses and other current liabilities	9,646	9,764
Contract liabilities	476	987
Convertible notes	5,384	8,594
Total current liabilities	17,715	22,563
Operating lease liabilities, noncurrent	16,287	16,681
Other noncurrent liabilities	112	126
Total liabilities	34,114	39,370
COMMITMENTS AND CONTINGENCIES (Note 14)
STOCKHOLDERS’ EQUITY:
Preferred stock—$0.0001 par value: 1,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock—$0.0001 par value: 300,000,000 shares authorized; 170,969,581 and 163,099,124 shares issued and outstanding at March 31, 2023 and December 31, 2022	17	16
Additional paid-in capital	353,533	345,742
Accumulated other comprehensive loss	(810)	(1,279)
Accumulated deficit	(276,774)	(250,509)
Total stockholders’ equity	75,966	93,970
Total liabilities and stockholders’ equity	$ 110,080	$ 133,340