Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating Activities
Net loss	$ (13,226)	$ (13,994)
Adjustments to reconcile net loss to net cash used in operating activities:
(Gain) loss from change in fair value of derivative warrant liability	(3)	3,040
(Gain) from change in fair value of 2020 Notes embedded derivative	(394)	(2,347)
Loss on exchange of debt		2,202
Stock-based compensation	370	237
Depreciation and amortization	3,221	3,285
Non-cash interest expense	832	884
Other non-cash expense	1	6
Changes in operating assets and liabilities:
Accounts receivable	360	(389)
Inventories	(163)	516
Prepaid expenses and other current assets, deposits and other assets	(613)	(416)
Accounts payable, accrued expenses and long-term liabilities	(38)	(829)
Net cash used in operating activities	(9,653)	(7,805)
Investing Activities
Acquisitions of property, plant and equipment	(4,556)	(97)
Net cash used in investing activities	(4,556)	(97)
Financing Activities
Proceeds from issuance of common stock	9,647	22,415
Proceeds from exercise of common stock warrants		1,263
Debt and equity offering costs	(17)	(299)
Net cash provided by financing activities	9,630	23,379
Net (decrease) increase in cash and cash equivalents	(4,579)	15,477
Beginning of period	33,734	11,553
End of period	29,155	27,030
Cash paid for interest	344	850
Non-cash purchase of property, plant and equipment	506	16
Exchange of convertible debt into common stock		3,701
Accrued debt and equity issuance costs		61
Fair value of 2020 Notes embedded derivative liability upon conversion into common stock		2,193
Fair value of warrants at issuance and upon exercise, net		4,905
Shares of common stock sold but not paid		$ 14,130