Pulse Sensor : Working Principle and Its Applications

The Heartbeat rate information knowing is very useful while doing exercise, studying, etc. But, the heartbeat rate can be complicated to calculate. To overcome this problem, the pulse sensor or heartbeat sensor is used. This is a plug & play sensor mainly designed for Arduino board which can be used by makers, students, developers, artists who can utilize the heartbeat information into their projects. This sensor uses an easy optical pulse sensor along with amplification & cancellation of noise to make a circuit. By using this circuit, we can get fast and reliable heartbeat readings. This circuit can be operated with 4mA current and 5V voltage to use in mobile applications.

What is the Pulse Sensor?

An alternate name of this sensor is heartbeat sensor or heart rate sensor. The working of this sensor can be done by connecting it from the fingertip or human ear to Arduino board. So that heart rate can be easily calculated.


The pulse sensor includes a 24 inches color code cable, ear clip, Velcro Dots-2, transparent stickers-3, etc.

  • A color code cable is connected to header connectors. So this sensor is easily connected to an Arduino into the project without soldering.
  • An ear clip size is the same as a heart rate sensor and it can be connected using hot glue at the backside of the sensor to wear on the earlobe.
  • Two Velcro dots are completely sized toward the sensor at the hook side. These are extremely useful while making a Velcro strap to cover approximately a fingertip. This is used to cover the Sensor around the finger.
  • Transparent strikers are protection layers used to protect the sensor from sweaty earlobes and fingers. This sensor includes three holes in the region of the external edge so that one can easily connect anything to it.

Pulse Sensor Specifications

The main specifications of this sensor mainly include the following.

  • This is a hear beat detecting and biometric pulse rate sensor
  • Its diameter is 0.625
  • Its thickness is 0.125
  • The operating voltage is ranges +5V otherwise +3.3V
  • This is a plug and play type sensor
  • The current utilization is 4mA
  • Includes the circuits like Amplification & Noise cancellation
  • This pulse sensor is not approved by the FDA or medical. So it is used in student-level projects, not for the commercial purpose in health issues applications.

Pin Configuration

The heartbeat sensor includes three pins which discussed below.

  • Pin-1 (GND): Black Color Wire – It is connected to the GND terminal of the system.
  • Pin-2 (VCC): Red Color Wire – It is connected to the supply voltage ( +5V otherwise +3.3V) of the system.
  • Pin-3 (Signal): Purple Color Wire – It is connected to the pulsating o/p signal.

Pulse Sensor Circuit Diagram

Please refer to this link to know more about Pulse Sensor Circuit with its Applications.

How Does Pulse Sensor Work?

The pulse sensor working principle is very simple. This sensor has two surfaces, on the first surface, the light-emitting diode & ambient light sensor is connected. Similarly, on the second surface, the circuit is connected which is accountable for the noise cancellation& amplification.

The LED is located above a vein in a human body like ear tip or fingertip, however, it must be located on top of a layer directly. Once the LED is located on the vein, then the LED starts emitting light. Once the heart is pumping, then there will be a flow of blood within the veins. So if we check the blood flow, then we can check the heart rates also.

If the blood flow is sensed then the ambient light sensor will receive more light as they will be reproduced by the flow of blood. This small change within obtained light can be examined over time to decide our pulse rates.

How to use Pulse Sensor Arduino?

This sensor used in straight forward, however connecting it in the correct way matters. Because all types of electronic components are directly exposed to the sensor. So, it is mandatory to envelop this sensor by using hot glue, vinyl strip otherwise other types of non-conductive materials.

These sensors cannot be operated with wet hands. The sensor’s smooth side must be located on the pinnacle of the vein & press it. Generally, Velcro tapes or clips are utilized to get this force.


This sensor can be used by connecting it to the Arduino board. Once it is connected, then give the power supply with the help of VCC pin and GND pins. The operating voltage of this sensor is +5V or 3.3V. Once the sensor is connected to the development board such as Arduino, then we can use the readily accessible Arduino code to make things easier. Please refer to Arduino site for interfacing of Arduino with pulse sensor and its coding.

Applications of Pulse Sensor

The applications of pulse rate sensor include the following.

  • This sensor is used for Sleep Tracking
  • This sensor is used for Anxiety monitoring
  • This sensor is used in remote patient monitoring or alarm system
  • This sensor is used in Health bands
  • This sensor is used in complex gaming consoles

Thus, this is all about Pulse Sensor (Heartbeat / Heartrate Sensor). it is open-source and plug-and-play hardware.  This sensor can easily include live heartbeat information into their projects. This sensor includes two circuits like an optical amplifying & a noise eliminating. The connection of this sensor on earlobe otherwise fingertip can be done using a Clip, and connect it to Arduino board. So that heart rate can be easily measured. These sensors are used by developers, students, makers, athletes, artists, etc.