Best IR Sensor for IoT Projects – Types, Working, Interfacing, and Applications Explained

Introduction

An IR (Infrared) Sensor is an electronic device that detects infrared radiation from its surroundings. It is widely used in automation, obstacle detection, motion sensing, line following robots, and various electronic projects. IR sensors are compact, affordable, and easy to integrate into microcontroller-based systems.

This guide explains everything you need to know about IR sensors — their types, working principle, interfacing techniques, and real-world examples — to help you understand how IR technology enhances electronics and automation.

What is an IR Sensor?

An IR sensor is a device that detects infrared light emitted by objects. It operates in the infrared region (typically 700 nm to 1 mm) of the electromagnetic spectrum. IR sensors are commonly used to measure heat or detect motion. These sensors work based on two components:

• IR Transmitter (usually an IR LED) – emits infrared radiation.

• IR Receiver (usually a photodiode or phototransistor) – receives reflected IR radiation.

When the emitted IR light hits an object, it reflects back and is detected by the receiver, triggering a response.

How Does an IR Sensor Work?

IR sensors follow a simple working principle:

1. The IR LED emits infrared light continuously.

2. If an object comes in front of the sensor, the light reflects back.

3. The photodiode or phototransistor detects the reflected IR beam.

4. Based on the signal, the sensor module generates HIGH or LOW output (digital IR sensor), or varying analog output (analog IR sensor).

This working mechanism is widely used for proximity sensing and obstacle avoidance.

Types of IR Sensors

IR sensors are mainly categorized into the following types:

1. Active IR Sensor

• Has both transmitter and receiver.
• Emits IR beam and detects its reflection.
• Used in motion detectors, distance measuring, obstacle sensing.
• Example: IR obstacle sensor module.

2. Passive IR Sensor (PIR Sensor)

• Only detects emitted infrared radiation from heat sources (like humans or animals).
• No IR beam emission involved.
• Used in security systems and motion sensing.
• Example: PIR motion sensor.

3. Analog IR Sensor

• Gives continuous voltage output based on distance.
• Output changes with proximity.
• Suitable for precision distance measuring.

4. Digital IR Sensor

• Gives only two outputs: HIGH or LOW.
• Used in basic obstacle sensing.
• Very commonly used with Arduino and embedded boards.

Key Features of IR Sensors

• Low power consumption
• Compact size
• Affordable and widely available
• Non-contact detection
• Reliable for close-range object detection
• Simple interfacing with microcontrollers (Arduino, ESP32, etc.)

IR Sensor Applications

IR sensors are used in various fields and industries:

• Smart electronics – Touchless switches, IR remotes

• Robotics – Obstacle avoidance, line following robots

• Security systems – Intrusion detection using PIR sensors

• Industrial automation – Object counter, conveyor belt sensing

• Consumer electronics – TV remotes, smart fans, gesture controls

• Home automation – Automatic lighting systems

Interfacing IR Sensor with Microcontroller (Example)

Let’s take an example of interfacing an IR obstacle sensor module with Arduino Uno:

Components Required:

• Arduino Uno
• IR Sensor Module
• LED
• Jumper Wires
• Breadboard

Connection:

• IR Sensor VCC → Arduino 5V

• IR Sensor GND → Arduino GND

• IR Sensor OUT → Arduino Digital Pin 2

• LED Anode → Arduino Pin 13

• LED Cathode → GND