Device Structure Optimization And Sensitive Materials Research Of Gas Sensors

The gas sensor prepared by Sn O₂ has the advantages of low production cost,simple structure and high sensitivity,and is one of the earliest commercial and mass production gas sensor.Based on the nano-Sn O₂ powder doped with antimony,this paper attempts to improve the gas-sensing properties of Sn O₂ gas sensor from noble metal doping and structural improvement.The main contents and results of this paper are as follows:The relationship between heating power and temperature and the 3D thermal profile at the same power and the effect of ambient temperature on the heater were measured by thick film screen printing technique.The effects of heating rate and heat stability under the premise of adjusting the component substrate size and heater area can get a good heating efficiency,to ensure that sensitive materials can be uniform and stable heating.The experimental results show that the heating rate of the microheater is faster and the temperature of the heating layer is more stable,which is helpful to improve the stability of the components.Nanometer SnO₂ gas-sensitive powder was prepared by sol-gel method using Sn Cl₄ · 5H₂ O,Sb Cl₃,urea and so on.The nano-Sn O₂ powder was carried out by scanning electron microscopy?SEM?and X-ray diffraction?XRD?Observation and characterization.The results show that the average grain size of Sn O₂ powder prepared by sol-gel method is about 25 nm,the morphology is spherical,and the antimony ions enter Sn O₂ crystal lattice to replace the tin ion,and there is no other heterogeneous phase.0.1mol%,0.3mol% and 0.5mol% of antimony were incorporated in the Sn O₂ material,respectively,and the gas sensitivity of the element was measured,in which the properties of 0.1 mol% of antimony were best.The effects of Ag and Pt doping on gas sensing properties were investigated.The experimental results show that Ag doping can effectively inhibit the interference of acetone to ethanol.It was found that the sensitivity of Pt was greatly improved by Pt doping,and it was expected to be prepared with high concentration of ethanol.The results show that the sensitivity of the Sn O₂ gas sensor is mainly due to the grain boundary effect in the gas-sensitive material,and the grain boundary effect of the material is saturated and the sensitivity is sensitive.The results show that the sensitivity of the Sn O₂ gas sensor is low.The improvement comes mainly from the interaction between the surface of the element electrode and the sensitive material.Therefore,improving the surface structure of the electrode material and selecting the electrode material play an important role in improving the sensitivity of the element.The effects of double-layer thick film structure composed of different gas-sensing materials on the gas-sensing properties of the elements were studied.It is found that the double-layer thick film structure can change the sensitivity and selectivity of the gas sensor.This improvement has a great relationship with the order of the different gas-sensitive materials in the two-layer film.Although the properties of the upper film play a major role,the presence of the underlying film changes the conductive pathways of the material,thereby improving the gas sensing properties of the membrane.The mechanism may be related to the transi tion layer formed by the diffusion effect at the interface of the double-layer thick film.The effect of environmental humidity on the gas-sensing performance was studied.The effect of humidity on the lanthanum nitrate was improved by adjusting the energy of the element in Sn O₂.It was found that when the heating power was 0.195 W,the humidity impact is minimal.