In-Depth: Detect, Measure & Plot Heart Rate using Pulse Sensor & Arduino

The core of this system relies on photoplethysmography (PPG), an optical technique used to detect volumetric changes in blood circulation. The Pulse Sensor (Amped) integrates a bright green LED and an ambient light phototransistor. When placed against a fingertip or earlobe, the LED illuminates the microvascular tissue beneath the skin. As the heart beats, blood pulses through the capillaries, causing variations in the amount of light reflected back to the phototransistor. The sensor's onboard circuitry amplifies this optical signal and filters out ambient interference, converting it into a continuous analog voltage waveform. This analog output is routed to one of the analog input pins on the Arduino board. Using the Arduino IDE and the PulseSensor Playground Library, the microcontroller samples this analog stream in real time. The software processes the incoming data points, identifies the distinct peaks corresponding to individual heartbeats, and computes the beats-per-minute (BPM). Finally, users can visualize the live waveform and heart rate data on a computer screen by connecting the Arduino via a USB cable and utilizing built-in visualization tools like the Arduino Serial Plotter.