MQ135 Gas Sensor

The MQ135 gas sensor is an air quality monitoring module designed to detect a wide range of toxic gases and pollutants in the environment. It is particularly sensitive to ammonia (NH3), carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), benzene vapors, smoke, and some alcohol vapors, making it ideal for indoor and outdoor air pollution monitoring projects. Powered by 5V, it provides both an analog output, which changes according to gas concentration, and a digital output with an adjustable threshold, making it easy to integrate with Arduino, ESP32, Raspberry Pi, and other microcontrollers.

Main Features

• Operating voltage: 5V DC.

• Sensor type: semiconductor gas sensor.

• Detected gases: NH3, NOx, CO2, smoke, benzene, aromatic compounds, alcohol vapors, and other air pollutants.

• Typical detection range: about 10 to 1000 ppm depending on the gas.

• Available outputs: analog output and digital output with adjustable threshold via potentiometer.

• Fast response, stable performance, and long service life after warm-up.

• Suitable for educational, experimental, and prototyping use.

• Compact module format, easy to install on electronic projects.

Project Examples

• Air quality monitoring station for classrooms, offices, or homes.

• DIY weather or pollution monitoring station with real-time alerts.

• Smoke and dangerous gas detection system with buzzer or mobile notification.

• Arduino or Raspberry Pi educational project for learning gas sensors and data reading.

• Smart ventilation or home automation system triggered by poor air quality.

Areas of Use

• Air quality control in buildings, offices, laboratories, and workshops.

• Safety and prevention of toxic gas and smoke risks in domestic or light industrial environments.

• Technical training, research, and electronics education.

• IoT and smart home air monitoring systems.