KY-039 Finger Detection Heartbeat Measuring Sensor Module

Bright infrared (IR) LED and a phototransistor are used by the KY-039 Finger Detection Heartbeat Measuring Sensor Module to detect the finger’s pulse; each pulse causes a red LED to flash.

The phototransistor on the other side of the finger is used to obtain the flux emitted when the blood pressure pulses through the finger and causes a minor change in the phototransistor’s resistance. The LED represents the light side of the finger.

Since the phototransistor should be sufficiently sensitive because the majority of light passing through the finger is absorbed, we selected a very high resistance resistor, R1. To achieve the best outcomes, resistance can be chosen by experimentation. Maintaining the shield to prevent stray light from entering the phototransistor is crucial.

This is especially crucial for residential illumination since most lights there are based on 50 or 60 Hz fluctuations, which means that a slight heartbeat will produce a lot of noise.

Note: The HW-487 module continues to function as before.

Example Code:

// Pulse Monitor Test Script
int sensorPin = 0;
double alpha = 0.75;
int period = 100;
double change = 0.0;
double minval = 0.0;
void setup ()
{
Serial.begin (9600);
}
void loop ()
{
static double oldValue = 0;
static double oldChange = 0;

int rawValue = analogRead (sensorPin);
double value = alpha * oldValue + (1 – alpha) * rawValue;

Serial.print (rawValue);
Serial.print (“,”);
Serial.println (value);
oldValue = value;

delay (period);
}

Features:

• Detect finger pulse using an optical transistor and an infrared LED
• Compact & Tiny Module
• Simple to operate.