MQ-135 Gas Sensor Module For NH3, Alcohol, benzene, smoke , CO2 Detector Module

MQ-135 Air Quality & Gas Sensor Module

The MQ-135 Gas Sensor Module is a versatile air quality monitoring sensor designed to detect a wide range of harmful gases, including ammonia (NH₃), nitrogen oxides (NOx), carbon dioxide (CO₂), alcohol vapors, benzene, smoke, and other volatile compounds. Built using Metal Oxide Semiconductor (MOS) technology, it provides both analog and digital outputs, making it suitable for environmental monitoring, safety systems, and IoT applications.

The sensor features an integrated heating element that improves gas detection sensitivity by activating the sensing material. As the concentration of target gases increases, the sensor’s conductivity changes, producing a corresponding output signal that can be easily processed by microcontrollers such as Arduino, ESP32, Raspberry Pi, and other development platforms.

Key Features

Detects multiple gases including NH₃, NOx, CO₂, alcohol, benzene, and smoke.
High sensitivity and fast response time.
Provides both Analog (AO) and Digital (DO) outputs.
Adjustable sensitivity through onboard potentiometer.
Compatible with Arduino, ESP32, Raspberry Pi, and other microcontrollers.
Low-cost and reliable solution for air quality monitoring.
Durable design suitable for continuous operation.

Technical Specifications

Operating Voltage: 2.5V – 5V DC
Typical Operating Voltage: 5V DC
Current Consumption: Approximately 150mA
Output Type: Analog and Digital (TTL)
Digital Output Voltage: 0V – 5V
Detectable Gases:
- Ammonia (NH₃)
- Nitrogen Oxides (NOx)
- Carbon Dioxide (CO₂)
- Alcohol Vapors
- Benzene
- Smoke and Other Harmful Gases

Working Principle

The MQ-135 sensor operates using a heated semiconductor sensing element enclosed within a protective metal mesh. When target gas molecules come into contact with the sensing surface, the electrical resistance of the sensor changes. This resistance variation is proportional to the gas concentration in the surrounding air, allowing the module to generate corresponding analog and digital output signals for monitoring and analysis.