Derivative liability - Movement (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Derivative Liability Details 1
Opening balance	$ 2,859,832
Derivative liability on convertible notes and variable priced warrants	1,335,709	1,826,500
Fair value adjustments to derivative liability	422,539	1,033,332
Closing balance	$ 4,618,080	$ 2,859,832