Income Taxes (Detail) - The components of the deferred tax assets (USD $)	Dec. 31, 2012	Dec. 31, 2011
Net operating loss carry-forwards	$ 25,034,778	$ 21,588,554
Capitalized start-up cost and research and development cost	607,983	891,708
Research and development tax credit	1,389,625	1,239,795
Depreciation on property and equipment	(156,361)	(366,292)
Stock-based compensation	405,742	677,381
Reserves and accruals	719,909	666,336
Total deferred tax asset	28,001,676	24,697,482
Valuation allowance	(28,001,676)	(24,697,482)
Net deferred tax assets

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from in-process research and development costs expensed in connection with a business combination.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from compensation and benefits costs.

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- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from other reserves not separately disclosed.

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- Definition

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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