Heart rate is a very vital health parameter that is directly related to the soundness of the human cardiovascular system. This project describes a technique of measuring the heart rate through a fingertip using a PIC microcontroller. While the heart is beating, it is actually pumping blood throughout the body, and that makes the blood volume inside the finger artery to change too. This fluctuation of blood can be detected through an optical sensing mechanism placed around the fingertip. The signal can be amplified further for the microcontroller to count the rate of fluctuation, which is actually the heart rate.
Update: For those who are interested to replicate this project, you can use Easy Pulse sensor that covers the complete sensor and instrumentation part. Easy Pulse is a photoplethysmography-based pulse sensor using a similar circuit as described in this project.
Also check out the Arduino version of this project here.