This is Finger Measuring Heartbeat Sensor Module component is ideally suited to adding heartbeat sensing to your project. This detection module combines a phototransistor and IR LED, which when a finger is placed between will provide a varying signal. Reading this analog signal you can interpret a change in signal as a heartbeat. As a simple module it will suit use within a large range of projects based on microcontrollers such as Arduino boards and the Raspberry Pi. The module has a M2 mounting hole allowing for its easy attachment to a multitude of surfaces. Pin Description S Analog output 3 to 5V DC Input ? Ground.