Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 2,617	$ 803
Marketable securities	17,595	17,391
Prepaid expenses and other current assets	246	358
Total current assets	20,458	18,552
Property and equipment, net	4,845	5,053
Patent and trademark rights, net	924	1,080
Construction in progress	7,188	7,046
Other assets	134	136
Total assets	33,549	31,867
Current liabilities:
Accounts payable	1,471	1,271
Accrued expenses	2,659	1,228
Current portion of capital lease	31	33
Total current liabilities	4,161	2,532
Long-term liabilities
Long-term portion of capital lease	7	23
Redeemable warrants	13	14
Total liabilities	4,181	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 189,498,664 and 168,660,370, respectively	189	168
Additional paid-in capital	298,236	289,563
Accumulated other comprehensive income (loss)	54	(114)
Accumulated deficit	(269,111)	(260,319)
Total stockholders’ equity	29,368	29,298
Total liabilities and stockholders’ equity	$ 33,549	$ 31,867