MQ Series Gas Sensor Modules
The MQ series is a family of inexpensive, electrochemical metal-oxide semiconductor sensors designed to detect various gas concentrations in the air. Each module features an internal heater that brings the sensing element to its operating temperature, causing the resistance to change as specific gas molecules interact with the sensor's surface. These modules are widely used in home air quality monitors, industrial safety alarms, and environmental sensing projects.
Common MQ Sensor Variants
| Model | Primary Target Gas | Detection Range |
|---|---|---|
| MQ-2 | Smoke, LPG, Propane, Hydrogen | 300 – 10,000 ppm |
| MQ-3 | Alcohol Vapor (Ethanol) | 0.05 – 10 mg/L |
| MQ-4 | Natural Gas, Methane (CH4) | 200 – 10,000 ppm |
| MQ-5 | LPG, Natural Gas, Town Gas | 200 – 10,000 ppm |
| MQ-7 | Carbon Monoxide (CO) | 10 – 1,000 ppm |
| MQ-135 | Air Quality (NH3, Benzene, Smoke) | 10 – 1,000 ppm |
Product Features
- Dual Output Mode: Features both an Analog output (for measuring precise concentration) and a Digital output (for simple threshold detection).
- Adjustable Sensitivity: Onboard potentiometer allows you to set the digital trigger threshold for the DOUT pin.
- High Sensitivity: Optimized to detect even low concentrations of target gases with a fast response time.
- Pre-Heated Circuitry: Integrated heating element ensures the sensing material reaches the necessary chemical reactivity state.
- Breadboard Friendly: Standard 4-pin header layout for easy integration with Arduino, ESP32, and Raspberry Pi.
Technical Specifications
- Operating Voltage: 5V DC
- Heater Voltage: 5.0V ± 0.2V (AC or DC)
- Load Resistance: Adjustable (via onboard potentiometer)
- Heater Consumption: < 800mW
- Operating Temperature: -10°C to +50°C
- Preheat Time: Over 24 hours (Recommended for stable initial readings)
Pin Configuration
| Pin Label | Function | Description |
|---|---|---|
| VCC | Power | 5V DC Input |
| GND | Ground | Common Ground |
| D0 | Digital Out | TTL High/Low based on potentiometer threshold |
| A0 | Analog Out | Variable voltage (0V to VCC) based on gas concentration |
Important Calibration Notes
- Burn-in Period: New sensors require a "burn-in" period of 24–48 hours of continuous power to stabilize the sensing element before accurate readings can be taken.
- Warm-up Time: After power-on, the sensor typically requires 60–120 seconds for the heater to stabilize the resistance.
- Temperature Dependency: Resistance readings are affected by ambient humidity and temperature; for high-precision applications, compensation via a DHT11/DHT22 sensor is recommended.
Package Contents
- 1x MQ Series Gas Sensor Module (Selected Model)