Stockholders' equity (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 266,399	$ 320,148	$ 527,896	$ 910,691
Costs of services
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	696	0	5,008	0
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	73,204	70,288	135,422	106,684
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	177,025	199,179	349,128	282,478
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 15,474	$ 50,681	$ 38,338	$ 521,529