Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 4,105	$ 803
Marketable securities – unrestricted	17,449	17,391
Prepaid expenses and other current assets	333	358
Total current assets	21,887	18,552
Property and equipment, net	4,890	5,053
Patent and trademark rights, net	990	1,080
Construction in progress	7,107	7,046
Other assets	136	136
Total assets	35,010	31,867
Current liabilities:
Accounts payable	1,217	1,271
Accrued expenses	1,740	1,228
Current portion of capital lease	31	33
Total current liabilities	2,988	2,532
Long-term liabilities
Long-term portion of capital lease	15	23
Redeemable warrants	14	14
Total liabilities	3,017	2,569
Commitments and contingencies (Notes 6,8,10)
Stockholders’ equity:
Preferred stock, par value $0.01 per share, authorized 5,000,000; issued and outstanding; none	0	0
Common stock, par value $0.001 per share, authorized 350,000,000 shares; issued and outstanding 183,285,228 and 168,660,370, respectively	183	168
Additional paid-in capital	296,058	289,563
Accumulated other comprehensive loss	(93)	(114)
Accumulated deficit	(264,155)	(260,319)
Total stockholders’ equity	31,993	29,298
Total liabilities and stockholders’ equity	$ 35,010	$ 31,867