Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net loss	$ (3,836)	$ (3,611)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of property and equipment	167	179
Amortization and abandonment of patent and trademark rights	165	4
Redeemable warrants valuation adjustment	0	(89)
Equity-based compensation	88	121
Change in assets and liabilities:
Prepaid expenses and other current assets	25	29
Accounts payable	(16)	(358)
Accrued expenses	512	(2,126)
Net cash used in operating activities	(2,895)	(5,851)
Cash flows from investing activities:
Purchase of property, equipment and construction in progress	(65)	(244)
Additions to patent and trademark rights	(75)	(46)
Maturities of short-term and long-term marketable securities	0	5,530
Purchase of short-term and long-term marketable securities	(37)	0
Net cash provided by (used in) investing activities	(177)	5,240
Cash flows from financing activities:
Payments on capital leases	(11)	(13)
Proceeds from sale of stock, net of issuance costs	6,385	0
Net cash provided by (used in) financing activities	6,374	(13)
Net increase (decrease) in cash and cash equivalents	3,302	(624)
Cash and cash equivalents at beginning of period	803	2,212
Cash and cash equivalents at end of period	4,105	1,588
Supplemental disclosures of non-cash investing and financing cash flow information:
Issuance of common stock for accounts payable and accrued expenses	38	134
Unrealized gain on marketable securities	21	36
Supplemental disclosure of cash flow information:
Cash paid for interest expense and capitalized construction interest	$ 0	$ 49