Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current Assets
Cash and cash equivalents	$ 15,954	$ 23,906
Accounts receivable, net	160	238
Inventories	2,249	2,218
Prepaid expenses and other current assets	1,555	1,258
Total current assets	19,918	27,620
Property and equipment, net	2,820	3,211
Operating lease right-of-use-assets	2,393	2,484
Other non-current assets	131	123
TOTAL ASSETS	25,262	33,438
Current Liabilities
Accounts payable	977	571
Accrued expenses	2,213	4,348
Current portion of deferred revenue	1,777	1,801
Current portion of equipment financing		265
Current portion of promissory note	674	421
Current portion of operating lease liabilities	338	356
Total current liabilities	5,979	7,762
Deferred revenue	617	686
Promissory note	1,326	1,579
Operating lease liabilities	2,195	2,264
Total liabilities	10,117	12,291
Commitments and contingencies (Note 13)
Stockholders’ Equity
Preferred stock, $0.0001 par value, 10,000,000 authorized none issued
Common stock, $0.0001 par value, 300,000,000 shares authorized; 3,259,340 and 3,188,679 issued and outstanding at March 31, 2021 and December 31, 2020, respectively	7	7
Additional paid-in capital	175,576	174,342
Accumulated deficit	(160,438)	(153,202)
Total stockholders’ equity	15,145	21,147
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 25,262	$ 33,438