Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net loss	$ (7,894)	$ (5,308)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of property and equipment	350	296
Amortization of patent and trademark rights	87	5
Redeemable warrants valuation adjustment	(191)	(236)
Equity-based compensation	219	90
Change in assets and liabilities:
Inventories	453	(211)
Increase (Decrease) in Prepaid Expense and Other Assets	(37)	106
Accounts payable	(1,026)	256
Accrued expenses	(1,590)	(476)
Net cash used in operating activities	(9,629)	(5,478)
Cash flows from investing activities:
Purchase of property, equipment and construction in progress	(534)	(3,208)
Additions to patent and trademark rights	(122)	(28)
Deposits on capital leases refunded	3	7
Prepaid expenses and other current assets	(74)	0
Maturities of short-term and long-term marketable securities	9,479	7,216
Purchase of short-term and long-term marketable securities	0	(2,057)
Net cash provided by investing activities	8,752	1,930
Cash flows from financing activities:
Payments on capital leases	(29)	(25)
Proceeds from margin account loan	0	2,640
Net cash provided by (used in) financing activities	(29)	2,615
Net decrease in cash and cash equivalents	(906)	(933)
Cash and cash equivalents at beginning of period	2,212	3,103
Cash and cash equivalents at end of period	1,306	2,170
Supplemental disclosures of non-cash investing and financing cash flow information:
Issuance of common stock for accounts payable and accrued expenses	164	133
Unrealized gain (loss) on marketable securities	(1,044)	655
Redeemable warrants valuation adjustment	191	236
Supplemental disclosure of cash flow information:
Cash paid for interest expense and capitalized construction interest	$ (98)	$ (33)