CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2022
CURRENT ASSETS:
Cash and cash equivalents	$ 63,204	$ 75,183
Restricted cash		621
Accounts receivable, less allowance of $248 and $321 as of March 31, 2024 and December 31, 2023, respectively	5,343	3,189
Unbilled receivables	895	942
Inventory	7,298	6,582
Prepaid expenses and other current assets	2,950	2,391
Total current assets	79,690	88,908
Property and equipment, net	3,706	2,999
Other long term assets	2,047	2,292
Total assets	85,443	94,199
CURRENT LIABILITIES:
Accounts payable	2,532	1,214
Deferred grant funding		621
Deferred revenue	1,527	1,453
Accrued expenses and other current liabilities	4,663	5,419
Total current liabilities	8,767	8,768
Long term deferred revenue	1,021	968
Other noncurrent liabilities	17	64
Total liabilities	9,805	9,800
COMMITMENTS AND CONTINGENCIES (NOTE 13)
STOCKHOLDERS' EQUITY:
Additional paid-in capital	339,201	338,114
Accumulated deficit	(263,570)	(253,722)
Total stockholders' equity	75,638	84,399		$ 123,722
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	85,443	94,199
Class A Common Stock
STOCKHOLDERS' EQUITY:
Common stock	5	5
Class B Common Stock
STOCKHOLDERS' EQUITY:
Common stock	2	2
Related Party
CURRENT LIABILITIES:
Due to related parties	$ 45	$ 61