App turns smartphone into a medical monitor

Users of the Pulse Phone app may be justifiably impressed at the way in which it lets them measure their heart rate, simply by placing their finger over their iPhone's camera lens. Well, a biomedical engineer at Worcester Polytechnic Institute (WPI) in Massachusetts has taken that concept several steps farther. Inspired by Pulse Phone, Prof. Ki Chon developed an Android app that measures not only heart rate, but also heart rhythm, respiration rate and blood oxygen saturation - all through a finger against the lens. Measurements made by the app are said to be as accurate as those obtained using standard medical monitors.

The app was developed using a Motorola Droid smartphone, although Chon believes it could be easily adapted to other models.

To measure their vital signs, users simply place their finger lightly against the phone's camera lens. When processed by custom algorithms, subtle color changes in the light reflecting off the finger reveal how fast and rhythmically the user's heart is beating, along with how fast they're breathing, and how much oxygen is getting into their bloodstream.

In a test of the system, volunteers who were hooked up to traditional measurement devices performed breathing exercises, while simultaneously holding one finger on a phone running the app. The numbers obtained using both approaches reportedly matched.

Chon is now looking at adapting the app to recognize atrial fibrillation, the most common form of cardiac arrhythmia. He also plans on creating a version of the app for tablets, that could be used in home or clinical settings. "Imagine a technician in a nursing home who is able to go into a patient's room, place the patient's finger on the camera of a tablet, and in that one step capture all their vital signs," he said. "We believe there are many applications for this technology, to help patients monitor themselves, and to help clinicians care for their patients."

A paper on the WPI app was recently published in the journal IEEE Transactions on Biomedical Engineering.