Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating Activities
Net loss	$ (15,296)	$ (13,226)
Adjustments to reconcile net loss to net cash used in operating activities:
(Gain) from change in fair value of derivative warrant liability	(8)	(3)
Loss (gain) from change in fair value of 2020/21 Notes and 2020 Notes embedded derivative liability	276	(394)
Loss on retirement of property, plant and equipment	38
Stock-based compensation	673	370
Depreciation and amortization	3,278	3,221
Non-cash lease expense	29	25
Non-cash interest expense	393	832
Other non-cash expense		1
Changes in operating assets and liabilities:
Accounts receivable	389	360
Inventories	721	(163)
Prepaid expenses and other current assets, deposits and other assets	164	(613)
Accounts payable, accrued expenses and long-term liabilities	(1,462)	(63)
Net cash used in operating activities	(10,805)	(9,653)
Investing Activities
Acquisitions of property, plant and equipment	(1,620)	(4,556)
Net cash used in investing activities	(1,620)	(4,556)
Financing Activities
Proceeds from SBA loans	1,006
Debt and equity offering costs	(115)	(248)
Proceeds from issuance of common stock	2,271	9,878
Net settlement of common stock under stock plans	(310)
Payment of loans payable - other	(392)
Net cash provided by financing activities	2,460	9,630
Net (decrease) increase in cash and cash equivalents	(9,965)	(4,579)
us-gaap_CashAndCashEquivalentsAbstract
Beginning of period	16,302	33,734
End of period	6,337	29,155
Cash paid for interest	693	690
Non-cash purchase of property, plant and equipment	32	506
Original issue discount paid with 2020/21 Notes	282
Right-of-use asset purchased with financing lease	13
Fair value of right-to-use asset and related lease liability upon adoption of ASC 842 - Leases		$ 1,244