US app developer Azumio has raised US2.5 million from Founders Fund, Accel Partners and Felicis Ventures, in a move that highlights the popularity of its flagship app. Azumio is the creator of Instant Heart Rate, which claims to be  “the world’s most popular biofeedback smartphone app" – as well as two other apps called Stress Check and Stress Doctor. 

All three apps rely on the same technique of a user holding a finger over their smartphone’s camera so allowing the app to monitor their heart rate. Instant Heart Rate has been downloaded more than 8 million times. It is available in both the App Store and the Android Market.

Bojan Bernard Bostjancic, Azumio’s co-founder and CEO, highlighted how the new funds will enable the company to speed up its development of new products. He said the company wanted to “introduce new services targeting today’s biggest health issues."