Stockholders' equity - Company Recognized Stock Compensation Expense (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 245,405	$ 261,497
Cost of Services [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	1,823	4,312
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	57,778	62,218
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	152,476	172,103
Sales and Marketing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 33,328	$ 22,864