MQ-2 Gas Sensor Explained briefly | Smoke, LPG & CO Detector

In the world of electronics and safety automation, the MQ-2 Gas Sensor plays a critical role in detecting harmful gases and smoke. Whether you’re building a gas leak alarm, an IoT-based air monitoring system, or a smart safety device, this sensor is the perfect choice for students, DIYers, and engineers alike.

🧠 What Is the MQ-2 Gas Sensor?

The MQ-2 is a semiconductor gas sensor that can detect a variety of gases including:

• 🔥 Liquefied Petroleum Gas (LPG)

• 🔥 Methane (CH4)

• 🔥 Propane (C3H8)

• 💨 Hydrogen (H2)

• 🌫️ Smoke

• ☠️ Carbon Monoxide (CO)

• 🍷 Alcohol vapors

This makes it suitable for home safety systems, smart kitchens, factories, school projects, and IoT setups.

⚙️ How Does the MQ-2 Sensor Work?

The MQ-2 contains a sensitive layer made of SnO₂ (tin dioxide), which reacts with gas molecules in the air. It also includes a heating element (coil) that helps to maintain a high temperature, improving sensitivity.

Here’s what happens:

1. The heater warms up the sensor’s sensitive surface.

2. When gases pass over it, the resistance of the surface changes.

3. This resistance change is converted into an electrical signal.

4. You can read this signal as analog or digital output using a microcontroller like Arduino.

🔌 Sensor Pin Configuration

• D0 (digital) output turns HIGH or LOW when the gas crosses a set threshold (set via onboard potentiometer).

• A0 (analog) output gives a continuous range showing the gas level intensity.

📦 Key Features of MQ-2:

• ⚡ Operating Voltage: 5V DC

• 📏 Detection Range: 300 ppm – 10,000 ppm (varies by gas)

• 🕒 Fast Response Time: <10 seconds

• 🔁 Preheat Time: 20 seconds (for accuracy)

• 🧪 Dual Outputs: Analog & Digital

• 🔧 Adjustable Sensitivity via onboard potentiometer

✅ Advantages

• ✔️ Low Cost and widely available

• ✔️ Compact and easy to mount

• ✔️ Works with Arduino, Raspberry Pi, ESP8266, NodeMCU

• ✔️ Ideal for DIY smoke alarms, gas leak detectors, and air quality monitors

• ✔️ Quick response & recovery time

🛠️ Applications

• 🏠 Home safety & kitchen gas leak detection

• 🏢 Industrial monitoring systems

• 🚪 Ventilation control and exhaust automation

• 🧠 STEM and academic projects

• 🌐 IoT air quality systems

• 🔔 Smoke & fire alarms

🎥 Video Tutorial & Demo

📺 Want to see MQ-2 in action?