Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net loss	$ (3,611)	$ (2,308)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of property and equipment	179	149
Amortization of patent and trademark rights	4	2
Redeemable warrants valuation adjustment	(89)	151
Equity-based compensation	121	36
Change in assets and liabilities:
Inventories	0	(211)
Prepaid expenses and other current assets	29	185
Accounts payable	(358)	775
Accrued expenses	(2,126)	(444)
Net cash used in operating activities	(5,851)	(1,665)
Cash flows from investing activities:
Purchase of property, equipment and construction in progress	(244)	(1,552)
Additions to patent and trademark rights	(46)	0
Deposits on capital leases refunded	0	6
Maturities of short-term and long-term marketable securities	5,530	3,189
Net cash provided by investing activities	5,240	1,643
Cash flows from financing activities:
Payments on capital leases	(13)	(13)
Proceeds from margin account loan	0	582
Net cash provided by (used in) financing activities	(13)	569
Net increase (decrease) in cash and cash equivalents	(624)	547
Cash and cash equivalents at beginning of period	2,212	3,103
Cash and cash equivalents at end of period	1,588	3,650
Supplemental disclosures of non-cash investing and financing cash flow information:
Issuance of common stock for accounts payable and accrued expenses	134	0
Unrealized gain on marketable securities	36	441
Redeemable warrants valuation adjustment	(89)	151
Supplemental disclosure of cash flow information:
Cash paid for interest expense and capitalized construction interest	$ 49	$ 11