Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities
Net loss	$ (23,199)	$ (15,302)
Adjustments to reconcile net loss to net cash used in operations:
Depreciation and amortization	1,382	1,381
Impairment of intangible assets	97	0
Impairment of property and equipment	204	0
Share-based compensation expense	877	721
Inventory write-downs	2,203	1,139
Other non-cash adjustments	0	99
Change in:
Accounts receivable, net	(29)	(5,029)
Costs and estimated earnings in excess of billings on uncompleted contracts	987	(400)
Inventory	(1,335)	55
Other current and non-current assets	2,021	(98)
Accounts payable	(982)	(1,416)
Accrued liabilities	(1,360)	(188)
Deferred revenue	28	0
Billings on uncompleted contracts in excess of related costs	0	(4)
Other currrent liabilities	(146)	(115)
Operating lease liabilities	(481)	0
Other long-term liabilities	0	(305)
Net cash used in operating activities	(19,733)	(19,462)
Cash flows from investing activities
Purchases of property and equipment	(671)	(971)
Net cash used in investing activities	(671)	(971)
Cash flows from financing activities
Principal payments under finance leases	(15)	(2)
Increase in deferred rent	0	139
Net proceeds from issuance of common stock	13,295	16,540
Net cash provided by financing activities	13,280	16,677
Change in cash and cash equivalents, and restricted cash	(7,124)	(3,756)
Cash, cash equivalents and restricted cash at beginning of period	14,201	17,401
Cash, cash equivalents and restricted cash at end of period	7,077	13,645
Supplemental schedule of non-cash investing and financing activities
Property and equipment acquired under finance leases	0	42
Non-cash additions to property and equipment	48	149
Issuance of common stock for commitment fee	$ 258	$ 0