The Analog CO/Combustible Gas Sensor(MQ9) module is useful for gas leakage detecting, it used the sensitive material SnO2, which with lower conductivity in clean air. It make detection by method of cycle high and low temperature, and detect CO when low temperature (heated by 1.5V). The sensors conductivity is more higher along with the gas concentration rising. ">The Analog CO/Combustible Gas Sensor(MQ9) module is useful for gas leakage detecting, it used the sensitive material SnO2, which with lower conductivity in clean air. It make detection by method of cycle high and low temperature, and detect CO when low temperature (heated by 1.5V). The sensors conductivity is more higher along with the gas concentration rising.Â