The MQ-9 Gas Sensor Module is a semiconductor gas sensor designed to detect Carbon Monoxide (CO), Methane (CH₄), and LPG gases. It uses SnO₂ sensitive material whose conductivity increases as gas concentration rises. The sensor operates using a cyclic heating method, detecting CO at low heater voltage (1.5V) and combustible gases such as Methane and Propane at high heater voltage (5V). This dual-temperature operation improves selectivity and stability. Suitable for gas leak detection systems, safety monitoring, and embedded industrial applications.
