Discontinued operations (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Discontinued operations
Current assets	$ 0	$ 1,959,494
Property, plant and equipment, net	0	725,930
Inventory, non-current	0	356,854
Goodwill	0	379,651
Intangible assets	0	467,575
Other assets	0	14,023
Total assets of discontinued operations	0	3,903,527
Total liabilities of discontinued operations	$ 0	$ 646,452