Design And Performance Analysis Of CO₂ Gas Thermal Conductivity Sensor Based On GO/α-Al₂O₃ Functional Material

As the main gas causing greenhouse effect,CO ₂ is widely used in environmental protectio n,energy development,agricultural cultivation,biological medicine and other fields.Accurate monitoring of CO ₂concentration distribution in real time is of great significance for predicting the world climate and maximizing the interests of related industries.The thermal conductivity gas sensor has become an ideal choice for detecting CO₂ gas due to its wide spectrum and low cost.At present,the thermal conductivity sensor generally has une ven temperature distribution and high radiation heat when it wor ks,which leads to its slow response time and low detection accuracy.The selection of gas-sensitive materials is the key to improve the performance of sensors.In recent years,due to the deve lopment of graphene and nano metal oxides and other functional m aterials,it provides a better medium for thermal conductivity sensors to detect CO ₂ gas.In order to improve the thermal stability and sensing performance of the thermal conductivity sensor,t he GO/α-Al₂O₃thermal conductivity gas sensor was designed and developed by using the elliptical resistance wire structure adapted to the shape of the carrier material and using the outer core of the carrier material andα-Al₂O₃ as the core of the carrier material.Specific research contents are as follows:1.According to the working mechanism of the thermal conductivity sensor,the main factors affecting the performance of the thermal conductivity sensor are introduced.The GO/α-Al₂O₃ thermal conductivity gas sensor structure is designed,and compared with the traditional thermal conductivity sensor,the simulation analysis is conducted to determine the stability of the temperature field of the designed structure.2.The GO carrier material was prepared by th e concentrated sulfuric acid oxidation intercalation method,theα-Al₂O₃ carrier material was prepared by the chemical precipitation method,and the GO/α-Al₂O₃thermal conductivity gas sensor was prepared by the carrier material hot wire coating and high t emperature sintering process.A test system for the thermal conductivity gas sensor is built,and a constant temperature detection circuit is used to improve the detection accuracy,and the hardware selection and software module design are completed accord ing to the functional requirements of the test system.3.The structure morphology and surface chemical composition of the prepared GO andα-Al₂O₃ carrier materials were characterized by transmission electron microscopy（TEM）,Raman spectra and X-ray（XRD）.The characterization results prove that GO has a good thermally conductive micro-sheet structure,andα-Al₂O₃ is in the form of stable particles.4.Taking CO₂ as the target gas for performance test,GO/α-Al₂O₃thermal conductivity gas sensor has good selectivity to CO ₂ gas.Compared with the traditional therm al conductivity gas sensor,the response time is shortened to 27s,the recovery time is shortened to 16s,and the average sensitivity is 0.28m V/1%CO ₂,which improves the power utilization rate.