Air pollution has become a major problem that has plagued people's lives in recent years. The quality of air quality has a serious impact on the quality of life and work efficiency, which has led to a continuous increase in the demand for air quality testing. In addition, according to the released China Made 2025 industry plan, China's traditional industry will face a major upgrade of information and automation in the next few years, and gas sensors
will undoubtedly play a more important role in this process. With the advancement of MEMS technology, gas sensors are also developing towards miniaturization, integration, and intelligence. With the growth of potential markets such as smart homes and smart wear, new gas sensor markets will inevitably continue to appear. It can be said that gas sensors are ready to take off in both the industrial and consumer markets.
A gas sensor is a converter that converts the volume fraction of a certain gas into a corresponding electrical signal. When a flammable gas exists in the environment where the gas sensor is located, the conductivity of the sensor increases with the increase of the concentration of the flammable gas in the air. A simple circuit can be used to convert the change in conductivity into an output signal corresponding to the gas concentration. High sensitivity to propane, butane, liquefied petroleum gas, and good sensitivity to natural gas. This gas sensor can detect a variety of flammable gases and is a low cost sensor suitable for many applications.
When the gas sensor works, under the action of a constant current source, current flows through the four arms of the bridge. When there is no flammable gas, the output of the bridge is balanced; when there is flammable gas, the flammable gas and oxygen are flamelessly burned on the surface of the measuring element. The electric bridge is balanced, and outputs an electric signal proportional to the concentration of flammable gas, and then sends this signal to the amplifier circuit to amplify. After the software is calibrated, the voltage is calculated and compared with the preset value through the voltage comparator. Monitoring of flammable gas concentrations.
The carrier thermal catalytic element uses the thermal effect of the reaction of methane and oxygen on the element surface to detect the methane concentration. The thermodynamic relationship of the element during its operation determines its operating characteristics. During operation, the element is placed in the detection gas chamber, and the working current is passed. For the compensation of the heat Q obtained by the component due to the operating current heating power conversion.