MQ-135 Air Quality Gas Sensor Module – Multi-Gas Detection for Pollution Monitoring

The MQ-135 Air Quality Gas Sensor Module is a high-sensitivity gas detection device designed to monitor a wide range of harmful gases present in the air. It is commonly used in air pollution monitoring systems, indoor air quality assessment, and IoT-based environmental monitoring projects. The sensor is capable of detecting gases such as ammonia (NH₃), alcohol vapors, benzene, smoke, carbon dioxide (CO₂), and other harmful air pollutants. The module provides both analog and digital outputs, allowing flexible and easy interfacing with microcontrollers such as Arduino, Raspberry Pi, ESP32, ESP8266, PIC, ATmega, and STM32 platforms.

WORKING PRINCIPLE

The MQ-135 operates using a metal oxide semiconductor (MOS) sensing element whose resistance changes when exposed to different gases. When harmful gases are present, the sensor’s internal resistance varies according to the gas concentration. This change is converted into an electrical signal that can be measured as an analog voltage or compared against a preset threshold to generate a digital output. An onboard potentiometer allows users to adjust the sensitivity and detection threshold, making the module adaptable to various air quality monitoring applications.

KEY FEATURES

The module can detect multiple gases including ammonia, alcohol, benzene, smoke, carbon dioxide, and other air pollutants. It operates at 5 V DC and provides both analog and digital outputs with an adjustable threshold. The MQ-135 offers high sensitivity, fast response time, and stable performance. Its sensing element is durable and designed for long service life. The compact 4-pin interface allows quick and easy integration with most microcontroller platforms.

APPLICATIONS

The MQ-135 Gas Sensor Module is ideal for air quality and pollution monitoring, indoor air purification systems, IoT-based environmental monitoring devices, smart home automation, industrial gas detection, school and university laboratory experiments, as well as robotics and automation projects.

WHY CHOOSE THE MQ-135 MODULE

The MQ-135 offers reliable multi-gas detection at an affordable cost, making it an excellent choice for environmental monitoring applications. Its wide gas detection capability, adjustable sensitivity, and compatibility with popular microcontrollers make it suitable for hobbyists, engineers, and IoT developers seeking an effective air quality sensing solution.