Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:
Net loss	$ (12,994)	$ (13,030)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of property and equipment	500	504
Amortization and abandonment of patent and trademark rights	414	144
Redeemable warrants valuation adjustment	(1)	(229)
Equity-based compensation	260	292
Change in assets and liabilities:
Inventories	0	453
Prepaid expenses and other current assets	123	(10)
Accounts payable	1,214	(197)
Accrued expenses	553	(1,573)
Net cash used in operating activities	(9,931)	(13,646)
Cash flows from investing activities:
Purchase of property, equipment and construction in progress	(386)	(747)
Additions to patent and trademark rights	(187)	(184)
Deposits on capital leases refunded	2	3
Deposit paid on office lease	0	(74)
Maturities of short-term and long-term marketable securities	1,222	14,070
Net cash provided by investing activities	651	13,068
Cash flows from financing activities:
Payments on capital leases	(24)	(36)
Proceeds from sale of stock, net of issuance costs	9,763	0
Net cash provided by (used in) financing activities	9,739	(36)
Net increase (decrease) in cash and cash equivalents	459	(614)
Cash and cash equivalents at beginning of period	803	2,212
Cash and cash equivalents at end of period	1,262	1,598
Supplemental disclosures of non-cash investing and financing cash flow information:
Issuance of common stock for accounts payable	38	237
Unrealized loss on marketable securities	0	(93)
Supplemental disclosure of cash flow information:
Cash paid for interest expense and capitalized construction interest	$ (9)	$ (144)