MQ-9 Gas Sensor Module – Carbon Monoxide & Combustible Gas Detection Sensor

The MQ-9 Gas Sensor Module is a highly reliable and sensitive gas detection device designed to detect Carbon Monoxide (CO) as well as combustible gases such as methane (CH₄) and liquefied petroleum gas (LPG). It is widely used in safety, industrial, and environmental monitoring systems where early detection of hazardous gases is critical. The module provides both analog and digital output signals, allowing easy interfacing with microcontrollers such as Arduino, Raspberry Pi, ESP32, PIC, STM32, and other embedded platforms. Its fast response time, stable performance, and durable sensing element make it suitable for continuous monitoring and real-time gas detection applications.

WORKING PRINCIPLE

The MQ-9 operates using a metal oxide semiconductor (MOS) sensing element combined with a built-in heating element. When carbon monoxide or flammable gases are present, they interact with the sensor’s sensitive surface, causing a change in its electrical resistance. This change is converted into an analog voltage output that corresponds to the gas concentration. The module also includes a comparator circuit that compares the signal with a preset threshold to generate a digital HIGH or LOW output. An onboard potentiometer allows sensitivity and threshold adjustment, enabling accurate detection under different environmental conditions.

KEY FEATURES

The MQ-9 is capable of detecting both carbon monoxide and combustible gases such as methane and LPG. It operates at 5 V DC and provides analog and digital outputs with adjustable sensitivity via an onboard potentiometer. The sensor offers high sensitivity, fast response, and stable long-term performance. Its sensing element is designed for durability and long service life, and the compact 4-pin module design allows easy integration with a wide range of microcontrollers and embedded systems.

APPLICATIONS

The MQ-9 Gas Sensor Module is ideal for carbon monoxide leak detection, LPG and methane leak alarms, home safety systems, industrial gas monitoring, smart IoT-based gas detection projects, robotics and automation systems, as well as school and engineering laboratory experiments.

WHY CHOOSE THE MQ-9 SENSOR MODULE

The MQ-9 offers dual-gas detection capability, making it a versatile and cost-effective solution for applications where multiple hazardous gases must be monitored simultaneously. Its reliability, ease of use, adjustable sensitivity, and broad microcontroller compatibility make it suitable for beginners, hobbyists, and professional engineers alike.