MagiDeal New Heart Rate Pulse Sensor Module Finger Earlobe For Arduino Pulse Sensor can be put on the finger or earlobe, through interconnected line can be connected to the Arduino, to test the heart rate Students, artists, athletes, creator, game developer, or mobile terminal can develop interactive work related to heart rate. It also has an open source app, can real time your heart rate graph display. Essence is a integrated optical amplifying circuit and noise eliminating circuit heart rate sensor. The power supply voltage: 3.3V ~ 5 v