The Geek Pub guide will help get you started with an Arduino pulse sensor. While sensors like this are reliable, it's worth keeping in mind that your heart rate can tell you a lot of different things.

Sometimes, a project comes along that makes a good reference design for anyone doing similar work. In this particular case, it’s a DIY USB polygraph-like machine by [Juangg] usi ...

Besides the Arduino’s serial monitor, we also used our DSO to measure pulse output from the water flow sensor. In that crude experiement, serial monitor displayed a rate of 56 Litre/hour (in lieu of ...