What is an IR Sensor: Working Principle Explained

Infrared technology is used for many devices and applications that we use in our daily life. Remote controls, sensing devices, and parking sensors are some of the common applications everyone knows. Understanding the functionality of infrared sensors allows you to create better knowledge of how these devices are working. You should know what is an IR sensor and its working principle to answer those crazy questions thrown by your kids. Let us give you some general awareness about IR sensors here.

IR sensor Blog Intro - Guruface

Table of Contents

What is an IR Sensor

An electrical device that monitors and detects infrared radiation in its environment is called an infrared (IR) sensor. It is a tool that can recognize when something is in front of it.

History of Infrared Sensor

William Herschel, an astronomer, discovered infrared radiation in 1800. He found that the temperature beyond the red light was the highest after measuring the temperature of each color of light. Since its wavelength is longer than that of visible light, IR is invisible to the human eye. Infrared radiation is produced by everything that radiates heat.

Features of IR Waves

IR sensors work with infrared light, which has a wavelength between 0.75 to 1000 m and is found between visible and microwave spectrums. Human eyes cannot see the IR region.

Wavelength Regions of Infrared Spectrum

Near IR – 0.75µm to 3 µm

Mid IR – 3 µm to 6 µm

Far IR – > 6 µ

Types of IR Sensor

There are two types of infrared sensors:

  1. Active IR Sensor
  2. Passive IR sensor

Active infrared sensors emit and detect infrared radiation. Active IR sensors have two parts:

  • TRANSMITTER – a light emitting diode (LED)
  • RECEIVER – A photodiode
Learn how an IR sensor works - Guruface blog

An IR sensor is made up of an IR LED and an IR Photodiode, which are collectively referred to as a Photo- or Opto-Coupler. IR LEDs produce IR light. The infrared light from the LED strikes the object as it approaches the sensor, reflects off of it, and the receiver picks it up. Based on its intensity, the IR Receiver detects radiation, which is then processed further. IR receiver output is often low, thus amplifiers are utilized to increase the signal that is being detected.

IR sensor working principle - Guruface blog

IR Sensor Interface with Arduino

IR Sensor Interface with Arduino - Guruface

Reverse Alarm for Car Using IR Sensor and Arduino

All contemporary vehicles come with reverse parking sensors, which work when the vehicle is in reverse gear and beeps at varying rates depending on how close the vehicle is to the nearest object. Reversing alarms may efficiently safeguard your automobile from harm while monitoring your reversing status and enhancing parking safety. When a car is approaching an item too closely, an IR sensor monitors the distance and alerts the driver.

Parking IR sensors in cars - Guruface blog
What is an Infrared sensor - Guruface blog

Tesla co-founder Martin applauded HARMAN’s in-car infrared sensor technology, which allows controlling car features through gestures. It is a fact that accessing the tablet-like touch screens on most car dashboards today while driving is not practical always. That’s one example of how IR sensors are enhancing our daily activities.

Program for Reverse Indicator with Light and Alarm

#define ir 7
#define buzzer 8
#define led 9

//Create variable to test against for sensor int obstacle;

void setup() {
//Set ir pin for INPUT so that it reads from the sensor
  pinMode(ir, INPUT);
//Set led and buzzer to OUTPUT so that they can be turned on/ off
  pinMode(led, OUTPUT);

void loop() {
//read from the IR sensor and assign value to obstacle variable
  obstacle = digitalRead(ir);

//if IR Sensor detects something then turn the buzzer on, and led oN
if (obstacle == HIGH)
 	digitalWrite(led, HIGH);
 	digitalWrite(buzzer, HIGH);
//if IR Sensor does not detect something turn led oFF, and buzzer off
 	digitalWrite(led, LOW);
 	digitalWrite(buzzer, LOW);



Active IR sensors are commonly known as proximity sensors and are used in obstacle detection systems, distance measurement, Item counters, etc.

In a recent blog, we explained what is a servo motor, its characteristics, and its capabilities. That is also one topic kids may find interesting.

Advantages of Infrared Sensor

  • Low power requirement
  • High noise immunity
  • Resistance to rust, corrosion, and other environmental effects
  • Reliability
  • Ability to be used across a vast region for real-time sensing

Disadvantages of Infrared Sensor

  • High-force infrared waves can damage the eyes.
  • It can only operate one device at a time in the screen and control application.
  • Get obstructed by everyday items.
  • A small range.
  • Environmental factors including rain, fog, dust, and pollution may have an impact.
  • Transmission when compared to wired devices, the data rate is modest.

Check out our blog ‘10 Interesting Facts about Robots‘ to see how interesting robotics technology is and how amazing will be the learning experience. If you are interested in learning more about sensors, we would like to suggest our blog ‘What is an accelerometer and how it works‘.


We hope you got a better idea about what is an IR sensor and its working principles to a great extent. It is not something you can learn completely in a few minutes read. At Guruface we are presenting robotics and coding online courses for kids who are interested in tech topics. Parents are also welcome to accompany the little ones.

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We are also offering free live webinars every weekend. If you wish to get a one-on-one demo of what courses we are offering and more details about the mode of classes, you can also book a free demo instantly.

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Marini is the Senior Robotics Trainer at Guruface Academy. She holds a Master's Degree (MS) in Electronics and is an experienced Instructor with a demonstrated history of Training students across the Globe in Various Robotics platforms. Marini is also a Professional Stem Educator with sound knowledge of Electronics, Coding, Robotics, Artificial Intelligence, etc.