Fair Value Measurements (Tables)

6 Months Ended

12 Months Ended

Jun. 30, 2013

Dec. 31, 2012

Investments and Fair Value Measurements [Abstract]

Schedule of assets and liabilities measured at fair value

	June 30, 2013 (Unaudited)								December 31, 2012
	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
LIABILITIES:
Warrant liability	$	—	$	—	$	445,075	$	445,075	$	—	$	—	$	1,616,325	$	1,616,325
Total warrant liability	$	—	$	—	$	445,075	$	445,075	$	—	$	—	$	1,616,325	$	1,616,325

	December 31, 2012								December 31, 2011
	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
ASSETS:
Cash equivalents:
U.S. government securities	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Certificates of deposit		—		—		—		—		—		—		—		—
Total cash equivalents	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Short-term investments:
U.S. government securities (1)	$	—	$	—	$	—	$	—	$	3,506,205	$	—	$	—	$	3,506,205
Certificates of deposit		—		—		—		—		2,975,000		—		—		2,975,000
Total short-term investments	$	—	$	—	$	—	$	—	$	6,481,205	$	—	$	—	$	6,481,205
LIABILITIES:
Common Stock Warrants:
Common stock warrants	$	—	$	—	$	1,616,325	$	1,616,325	$	—	$	—	$	937,000	$	937,000
Total common stock warrants	$	—	$	—	$	1,616,325	$	1,616,325	$	—	$	—	$	937,000	$	937,000

 (1) Includes amortization premium paid of $8,733 as of December 31, 2011.

Schedule of estimated fair value of the warrant liability

	June 30,			December 31,
	2013			2012
	(Unaudited)
Stock price	$	0.51		$	1.25
Strike price	$	2.50		$	2.50
Remaining contractual term (years)		2.6			3.1
Volatility		141.8	%		171.9	%
Adjusted volatility		123.0	%		121.1	%
Risk-free rate		0.5	%		0.4	%
Dividend yield		0.0	%		0.0	%

	December 31,		December 31,
	2012		2011
Stock price	$	1.25	$	0.65
Strike price	$	2.50	$	2.50
Remaining contractual term (years)		3.1		4.1
Volatility		171.9%		215.5%
Adjusted volatility		121.1%		125.5%
Risk-free rate		0.4%		0.6%
Dividend yield		0.0%		0.0%