Basis of presentation (Details) (Fair Value, Measurements, Recurring [Member], USD $)	Mar. 31, 2013	Dec. 31, 2012
Assets
Derivative asset (warrant)	$ 28,320	$ 50,300
Liabilities
Derivative liabilities	3,451,046	4,497,977
Level 1 [Member]
Assets
Derivative asset (warrant)
Liabilities
Derivative liabilities
Level 2 [Member]
Assets
Derivative asset (warrant)	28,320	50,300
Liabilities
Derivative liabilities	3,451,046	4,497,977
Level 3 [Member]
Assets
Derivative asset (warrant)
Liabilities
Derivative liabilities