1.Sensitive material MQ-9 gas sensor is used to clean the air in the

lower conductivity of tin dioxide (SnO2). Detection method using low

temperature cycling (1.5V heating) to detect carbon monoxide,

conductivity sensors with carbon monoxide in the air increased with

increasing gas concentration, stray adsorbed at high temperatures

(5.0V heating) detection of combustible gases methane, propane

and cryogenic cleaning gases. Simple circuit can be used to change

the conductivity, concentration of the gas is converted to the

corresponding output signal. MQ-9 high gas sensor for carbon

monoxide, methane, liquefied petroleum gas sensitivity, the sensor

can detect a variety of gases containing carbon monoxide and

flammable, is a low-cost sensors for a variety of applications.