Turn your smartphone into comfortable personal heart rate monitor.
Measuring is based only on gyroscope sensor.

How to measure your heart rate:
* Sit on a chair and put the phone on your leg (quadriceps) or on heart side of chest or into armband
* Relax and hold still, keep your hands along side of your body
* Wait for detection of heart rate, it takes 10 - 15 s
* That's all!