Instead of relying on the iPhone’s microphone or extra hardware to measure a user’s heart rate like most other heart rate apps, Antimodular Inc.’s Pulse Phone does so by using the iPhone’s built-in camera. When the user places their finger over the iPhone camera, the app detects the changes in the intensity of light passing through the finger, which changes as blood pulses through the veins.

The app’s use of the iPhone’s camera by way of an (at the time) unauthorized “hack” of Apple’s code for the camera meant that the app was rejected when it was initially submitted to Apple over a year and a half ago. However, the recent relaxing of restrictions means Pulse Phone has now been approved. The use of the camera means that users can measure their pulse in noisy environments where microphone-based apps may struggle.

Pulse Phone works on older iPhone’s and will handle a variety of different ambient light conditions, although bright light yields the best results. However, with the use of the iPhone 4’s built-in flash, the app is even able to function in complete darkness – if measuring your pulse in complete darkness is your thing. Users can also save their readings and email them from within the app to keep a track of your heart rate over time.

Although there are other camera-based heart rate apps available, Pulse Phone developer Rafael Lozano-Hemmer believes his app’s image analysis is superior. Even so, a warning that appears when the app loads cautions against using the app for medical purposes.

Pulse Phone is available on the iTunes App Store for US$1.99.

Via Switched