Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (13,943)	$ (12,485)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash restructuring and impairment	2,943
Depreciation and amortization	322	881
Stock-based compensation	291	1,865
Loss (gain) on sales and disposals of property and equipment	44	(493)
Gain on extinguishment of promissory note		(2,023)
Changes in operating assets and liabilities:
Accounts receivable	4	10
Inventories	(57)	(108)
Prepaid expenses and other assets	(502)	(46)
Accounts payable	(501)	368
Accrued expenses	(3,039)	(2,359)
Other liabilities	(139)	(175)
Deferred revenue		(134)
Net cash used in operating activities	(14,577)	(14,699)
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds from sales of property and equipment		534
Purchases of property and equipment		(76)
Net cash provided by investing activities		458
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from issuance of common stock and warrants	12,670	11,022
Payments of offering costs related to the issuance of common stock and warrants	(2,040)	(228)
Proceeds from exercise of warrants	25
Proceeds from issuance of common stock in connection with the employee stock purchase plan	5	26
Payments on equipment financing		(265)
Net cash provided by financing activities	10,660	10,555
NET CHANGE IN CASH AND CASH EQUIVALENTS	(3,917)	(3,686)
CASH AND CASH EQUIVALENTS, beginning of period	15,045	23,906
CASH AND CASH EQUIVALENTS, end of period	11,128	20,220
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Unpaid offering costs	$ 890	84
Unpaid property and equipment		109
Transfer of lasers from inventories to property and equipment		3
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash payments for interest		2
Cash payments for income taxes		$ 2