Stockholders' equity (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 178,752	$ 261,540	$ 706,648	$ 1,172,231
Cost of services
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	0	0	5,008	0
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	45,945	59,688	181,367	161,819
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	98,683	156,236	447,811	443,267
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 34,124	$ 45,616	$ 72,462	$ 567,145