Accounts receivable, net (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Provision for Doubtful and Other Accounts	$ 30,608	$ 58,728
Allowance for Doubtful Accounts Receivable, Write-offs	2,792,806
Allowance for Doubtful Accounts Receivable Reversal	$ 338,359	$ 100,213