• 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.
• The essence is an integrated optical amplifying circuit and noise eliminating circuit heart rate sensor.
• The power supply voltage: 3.3V ~ 5 v

This is a Tutorial of how to do Pulse/ Heartbeat Rate (BPM) Measurement using Arduino :

In this article, we are going to interface a Pulse Sensor with Arduino. The pulse sensor we are going to use is a plug and play heart rate sensor. This sensor is quite easy to use and operate. Place your finger on top of the sensor and it will sense the heartbeat by measuring the change in light from the expansion of capillary blood vessels. When a heartbeat occurs blood is pumped through the human body and gets squeezed into the capillary tissues. The volume of these capillary tissues increases as a result of the heartbeat. But in between the heartbeats (the time between two consecutive heartbeats,) this volume inside capillary tissues decreases. This change in volume between the heartbeats affects the amount of light that will transmit through these tissues. This change is very small but we can measure it with the help of Arduino.

#include
#define USE_ARDUINO_INTERRUPTS true    // Set-up low-level interrupts for most acurate BPM math.
#include      // Includes the PulseSensorPlayground Library.  
LiquidCrystal lcd(7,6,5,4,3,2); 

//  Variables
const int PulseWire = 0;       // PulseSensor PURPLE WIRE connected to ANALOG PIN 0
const int LED13 = 13;          // The on-board Arduino LED, close to PIN 13.
int Threshold = 550;           // Determine which Signal to "count as a beat" and which to ignore.
                               // Use the "Gettting Started Project" to fine-tune Threshold Value beyond default setting.
                               // Otherwise leave the default "550" value. 
                               
PulseSensorPlayground pulseSensor;  // Creates an instance of the PulseSensorPlayground object called "pulseSensor"


void setup() {   

  Serial.begin(9600);          // For Serial Monitor
  lcd.begin(16,2);

  // Configure the PulseSensor object, by assigning our variables to it. 
  pulseSensor.analogInput(PulseWire);   
  pulseSensor.blinkOnPulse(LED13);       //auto-magically blink Arduino's LED with heartbeat.
  pulseSensor.setThreshold(Threshold);   

  // Double-check the "pulseSensor" object was created and "began" seeing a signal. 
   if (pulseSensor.begin()) {
    Serial.println("We created a pulseSensor Object !");  //This prints one time at Arduino power-up,  or on Arduino reset.  
    lcd.setCursor(0, 0); 
  
  }
}



void loop() {

 int myBPM = pulseSensor.getBeatsPerMinute();  // Calls function on our pulseSensor object that returns BPM as an "int".
                                               // "myBPM" hold this BPM value now. 

if (pulseSensor.sawStartOfBeat()) {            // Constantly test to see if "a beat happened". 
 Serial.println("♥  A HeartBeat Happened ! "); // If test is "true", print a message "a heartbeat happened".
 Serial.print("BPM: ");                        // Print phrase "BPM: " 
 Serial.println(myBPM);  
 // Print the value inside of myBPM.
 lcd.setCursor(0, 0);
 lcd.println("   Pulse Rate   "); 
 lcd.setCursor(0, 1);
 lcd.print("Beat Per Min:");                       
 lcd.print(myBPM); 
 
}
delay(100);                    // considered best practice in a simple sketch.

}