Description
The MQ-2 Smoke Gas Sensor is a low-cost, highly sensitive semiconductor gas detection module designed for monitoring flammable gases and smoke in domestic, industrial, and automotive environments. Built around the MQ-2 sensor with a tin dioxide (SnO₂) sensing layer, this module responds to a broad range of combustible gases including LPG, propane, butane, methane, hydrogen, alcohol vapors, and smoke. It is an ideal solution for home gas leak alarms, kitchen safety systems, fire detection prototypes, and educational sensor projects.
At the heart of the module is the MQ-2 sensor element, whose conductivity increases as the concentration of target gases rises. In clean air, the sensor exhibits low conductivity; when exposed to flammable gases or smoke, its resistance drops, producing a measurable change in output. The module provides two independent outputs: an analog output (AO) that varies continuously with gas concentration for trend monitoring, and a digital output (DO) that switches when the concentration exceeds a user-adjustable threshold set by the onboard potentiometer. This dual-output design makes it suitable for both quantitative trend analysis and simple threshold-based alarm triggering.
The module operates from 5V DC with a typical current consumption of approximately 150mA. It is compatible with Arduino, ESP32, and other 5V microcontrollers; Raspberry Pi users require an external ADC. The board features a compact form factor and an onboard LED indicator that provides visual feedback for power and digital output status.
Important Note: The MQ-2 requires a significant preheat time for stable operation. New sensors should be powered on for 24–48 hours in clean air before initial calibration. After each power-up, allow at least 20 seconds to 5 minutes for the heater to stabilize. The sensor is not selective — it cannot distinguish between specific gases and responds to all reducing gases. It is not a calibrated industrial-grade detector and should not be used as a sole life-safety device. Its sensitivity degrades over time, and periodic replacement is recommended for critical applications. The sensor surface becomes hot during operation — avoid touching it. The module is not waterproof and should be kept dry.
Whether you are building a home gas leak alarm, a kitchen safety system, or an educational sensor project, the MQ-2 module provides a reliable, affordable solution for broad-spectrum flammable gas and smoke detection.
Features
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MQ-2 SnO₂ semiconductor sensor — High sensitivity to LPG, propane, butane, methane, hydrogen, alcohol, and smoke
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Dual output — Analog (AO) for concentration trends, Digital (DO) for threshold alarms
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Adjustable threshold — Onboard potentiometer sets the digital output trigger point
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Wide detection range — 300–10,000 ppm for flammable gases
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5V operation — Compatible with Arduino, ESP32, and other 5V microcontrollers
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LED indicators — Power and digital output status feedback
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Compact form factor — 32 × 20mm PCB for easy integration
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Fast response — Quick detection of gas concentration changes
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Long lifespan — Specified for up to 10 years under proper operating conditions
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Wide application range — Home gas alarms, kitchen safety, industrial monitoring, education
Technical Specifications
| # | Parameter | Specification |
|---|---|---|
| 1 | Sensor Model | MQ-2 (SnO₂ semiconductor) |
| 2 | Target Gases | LPG, propane, butane, methane, hydrogen, alcohol, smoke |
| 3 | Detection Range | 300 – 10,000 ppm (flammable gas) |
| 4 | Operating Voltage | 5V DC |
| 5 | Heater Voltage | 5.0V ± 0.1V |
| 6 | Heater Power Consumption | ≤950mW |
| 7 | Output Type | Analog (AO) + Digital (DO/TTL) |
| 8 | Preheat Time | 24–48 hours (initial); 5–10 min (subsequent) |
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