Nature of business and organization (Details) - USD ($)	1 Months Ended	12 Months Ended
	Apr. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cumulative losses attributable to common shareholders		$ 23,760,629	$ 23,234,303	$ 17,980,689	$ 2,028,055
Cash and cash equivalents		2,798,744	3,002,557	506,283	3,335,275
Retained Earnings
Cumulative losses attributable to common shareholders		(132,142,209)	$ (118,914,567)	$ (108,532,508)	$ (99,273,861)
February 2020 Public Offering [Member]
Proceeds from issuance or sale of equity	$ 14,500,000	$ 14,500,000