MQ-135 Gas Sensor Module For NH3, Alcohol, benzene, smoke , CO2 Detector Module
🌫️ 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 NH₃ (Ammonia), Alcohol, Benzene, Smoke, and CO₂, 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 |
| ⏱ Response Time | < 10 seconds |
| 🔧 Output Type | Analog & Digital |
🧩 Detectable Gases
The MQ-135 sensor is sensitive to several gases:
| Gas Type | Description |
|---|---|
| 🌫 Ammonia (NH₃) | Industrial and agricultural gas |
| 🍺 Alcohol Vapors | Ethanol-based gases |
| 🧪 Benzene | Toxic industrial chemical |
| 🚬 Smoke | Combustion smoke detection |
| 🌍 Carbon Dioxide (CO₂) | Air quality indicator |
🔌 Pin Configuration
| Pin | Function |
|---|---|
| VCC | 5V Power Supply |
| GND | Ground |
| A0 | Analog Output (Gas concentration level) |
| D0 | Digital Output (Threshold detection) |
⚙️ How the Sensor Works
The MQ-135 works using a metal oxide semiconductor (MOS) gas detection principle.
Step-by-Step Process
1️⃣ A heating element inside the sensor warms the sensing material.
2️⃣ The sensing material is usually Tin Dioxide (SnO₂).
3️⃣ When gas molecules come in contact with the sensor surface, electrical resistance changes.
4️⃣ The module converts this resistance change into analog voltage output.
5️⃣ A comparator circuit can provide a digital signal when gas levels exceed a set threshold.
🧠 Main Components
🔹 Gas sensing element (SnO₂)
🔹 Heating coil
🔹 Comparator IC
🔹 Sensitivity adjustment potentiometer
🔹 Analog & Digital output pins
📐 Module Layout (Infographic)
MQ-135 Gas Sensor Module
┌───────────────┐
│ Gas Sensor │
│ (MQ135) │
└───────────────┘
🔧 Adjustable Potentiometer
[ Sensitivity ]
┌─────┬─────┬─────┬─────┐
│ VCC │ GND │ A0 │ D0 │
└─────┴─────┴─────┴─────┘
🤖 Common Applications
🔹 Indoor air quality monitoring systems
🔹 Smart home pollution detection
🔹 Industrial gas leakage detection
🔹 IoT environmental monitoring
🔹 Smart ventilation systems
🔹 Smoke detection systems
🔌 Compatible Development Boards
This sensor is commonly used with:
Arduino Uno
ESP32
Arduino Nano
Raspberry 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 (24–48 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:
✔ Detect pollution level
✔ Display air quality data
✔ Send alerts when air becomes unsafe
