MQ-2 Smoke and Gas Detection Sensor Module

The MQ-2 is a tin-dioxide gas sensor sensitive to a broad range of combustible gases and smoke at once - LPG, methane, propane, hydrogen, alcohol and carbon monoxide - rather than identifying one gas specifically, which makes it a general-purpose leak or smoke detector rather than a precision analyzer for any single gas. That breadth is exactly the point for a home safety project, where the goal is catching a dangerous situation rather than diagnosing which gas caused it.

It gives both an analog output that scales with concentration and a digital output that trips past a threshold set by the onboard potentiometer, so a project can either log gas levels over time or just wire a simple alarm off the digital pin. Response time is fast, and the sensor has a long service life under normal use, though like all MQ-series sensors it needs a short warm-up period after power-on before readings stabilize.

Common builds are home gas leak alarms, smoke detectors, and IoT air-quality or safety monitoring projects where catching a combustible gas leak matters more than measuring its exact concentration.