Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash	$ 40,406	$ 12,862
Accounts receivable, net of allowances of $28 and $42, respectively	4,662	3,224
Inventories	2,242	1,978
Prepaid expenses and other current assets	485	356
Total current assets	47,795	18,420
Property and equipment, net	991	1,172
Right-of-use assets	216	685
Other assets	164	320
Total assets	49,166	20,597
Current liabilities:
Accounts payable	3,107	1,501
Accrued liabilities	2,299	1,429
Deferred revenues, current	1,220	1,496
Lease liabilities, current	229	548
Total current liabilities	6,855	4,974
Deferred revenues, non-current	1,475	1,806
Notes payable, net	1,993	3,075
Lease liabilities	0	233
Warrant liabilities	1,550	6,037
Other non-current liabilities	74	38
Total liabilities	11,947	16,163
Commitments and contingencies (Note 15)
Stockholders' equity:
Convertible preferred stock, $0.001 par value; 10,000 shares authorized; no shares issued and outstanding at December 31, 2021 and 2020	0	0
Common stock, $0.001 par value; 141,429 shares authorized; 12,693 and 8,349 shares issued and outstanding at December 31, 2021 and 2020, respectively	13	8
Additional paid-in capital	246,090	204,376
Accumulated other comprehensive loss	(17)	(847)
Accumulated deficit	(208,867)	(199,103)
Total stockholders' equity	37,219	4,434
Total liabilities and stockholders' equity	$ 49,166	$ 20,597