The MQ-9 Analog Gas Sensor has high sensitity to Carbon Monoxide, Methane and LPG. The sensor can be used to detect different gases containing CO and combustible gases, it is low cost and suitable for a variety of applications.
The core sensing material of MQ-9 gas sensor is SnO2, which has a lower conductivity in clean air. It makes detection by cycling high and low temperature, and detects CO when low temperature (heated by 1.5V). The sensorís conductivity is higher along with the gas concentration rising. When temperature rises (heated by 5.0V), it detects Methane, Propane, combustible gas,etc and cleans the other gases adsorbed under low temperature.
Notice:The new version of analog sensor port pin mapping has been changed as the following two features.Please check the tips for changing sensor cable pin mapping while using the I/O Expansion shield. We will continue to update. For the inconvenience caused, please understand.