MQ-135 Gas Sensor Module for NH3, Alcohol, Benzene, Smoke, CO2 Detection
MQ-135 Gas Sensor Module
Air Quality Multi-Gas Detection Environmental Monitoring
The MQ-135 Gas Sensor Module is a popular gas sensor used for air quality monitoring and pollution detection. It can detect several harmful gases such as NH (Ammonia), Alcohol, Benzene, Smoke, and CO, making it useful for smart home systems, environmental monitoring, and IoT projects.
Infographic Overview
Basic Specifications
Feature | Details |
Operating Voltage | 5V DC |
Operating Current | ~150 mA |
Heating Consumption | < 800 mW |
Detection Type | Gas / Air Quality |
Detection Range | 10 1000 ppm |
mp; Digital |
Detectable Gases
The MQ-135 sensor is sensitive to several gases:
Gas Type | Description |
Ammonia (NH) | Industrial and agricultural gas |
Alcohol Vapors | Ethanol-based gases |
Benzene | Toxic industrial chemical |
Smoke | Combustion smoke detection |
Carbon Dioxide (CO) | Air quality indicator |
Pin Configuration
Pin | Function |
VCC | 5V Power Supply |
GND | Ground |
A0 | Analog Output (Gas concentration leveThreshold detection) |
How the Sensor Works
The MQ-135 works using a metal oxide semiconductor (MOS) gas detection principle.
Step-by-Step Process
1 A heating element inside the sensor warms the sensing material.2 The sensing material is usually Tin Dioxide (SnO).3 When gas molecules come in contact with the sensor surface, electrical resistance changes.4 The module converts this resistance change into analog voltage output.5 A comparator circuit can provide a digital signal when gas levels exceed a set threshold.
Main Components
Gas sensing element (SnO) Heating coil Comparator IC Sensitivity adjustment pbr> Gas Sensor (MQ135) Adjustable Potentiometer[ Sensitivity ] VCC GND A0 D0
Common Applications
ry Pi
Advantages
Detects multiple harmful gases Low cost and easy to use Analog and digital outputs Adjustable sensitivity Suitable for IoT and smart systems
Limitations
Requires preheating (2448 hours) for accurate readings Cannot identify exact gas type (only concentration changes) Affected by temperature and humidity Calibration needed for precise measurements
Typical Project Idea
Smart Air Quality Monitoring System
Components:
MQ-135 Gas Sensor
ESP32
OLED / LCD Display
Buzzer / LED
IoT dashboard
Functions: