Design And Optimization Of The Micro-hotplate For Micro-structural Gas Sensor

Gas sensor is closely related to people’s production and living, microstructuregas sensor plays a vital role because of its small size, high sensitivity, easy integration,functionalization, micro-hotplate is always the scholars’ main research object which isthe important part of the micro gas sensor.The article designed and optimized the micro-hotplate for micro-structure gassensor by using the finite element analysis software ANSYS. Through the design ofelectrodes and the substrate, and analysis of the thermal field and magnetic field, wecan get the micro-hotplate with high performance. The main contents are as follows:1. The design and optimization of Type I micro-hotplateType I micro-hotplate is designed, its size is1.5mm×1.0mm×300μm, and itsstructure is optimized. Through the optimization of the thermal field and magneticfield, in order to obtain highest temperature and uniform temperature distribution inthe Type I micro-hotplate, the thickness of electricity insulation layer(SiO2),substrate(Si), thermal insulation layer(SiO2) are40μm、110μm、150μm, the heatingwidth is200μm, the measuring electrode width is10μm and without interdigitatedstructure. The temperature in the center of the Type I micro-hotplate is350.32℃, andit is uniform. Through the optimization, the magnetic field in the center of themicro-hotplate is minimum and uniform, the value of3.81×10-5A/m, compared withthe maximum of magnetic field (Bmax=211.096A/m), the magnetic field in the centerof the micro-hotplate can be ignored, it can effectively reduce the influence ofmagnetic field distribution on the measuring signal.2. The design and optimization of Type II micro-hotplateThe new micro-hotplate structure is designed and optimized, its size is1.5mm×1.0mm×300μm. The thermal field and magnetic field are optimized by using thefinite element analysis software ANSYS. In order to obtain the best temperature distribution in the Type II micro-hotplate, the thickness of electricity insulationlayer(SiO2), substrate(Si), thermal insulation layer(SiO2) are50μm、100μm、150μm,the heating width and electrode space are20μm, the measuring electrode width is10μm and without interdigitated structure. The temperature in the center of the Type IImicro-hotplate is345.967℃, with the good uniformity of the temperature distribution.Through the optimization, the magnetic field in the center of the micro-hotplate isminimum and uniform, the value of2.19×10-7A/m, compared with the maximum ofmagnetic field (341.771A/m), the magnetic field in the center of the micro-hotplatecan be ignored, it can effectively reduce the interference of magnetic field distributionon the measuring signal.3. The design and optimization of Type III micro-hotplateThe new micro-hotplate structure is designed with the size of1.5mm×1.0mm×300μm. The thermal field and magnetic field are optimized by using the finiteelement analysis software ANSYS, the thickness of electricity insulation layer(SiO2),substrate(Si), thermal insulation layer(SiO2) are26μm、124μm、150μm, the heatingwidth and electrode space are20μm and10μm, the measuring electrode width is10μm and without interdigitated structure. The Type III micro-hotplate obtains thebest temperature distribution, and the temperature in the center of is346.445℃.Through the optimization, the magnetic field in the center of the micro-hotplate isminimum and uniform, the value of4.57×10-7A/m, compared with the maximum ofmagnetic field (426.018A/m), the magnetic field in the center of the micro-hotplatecan be ignored, it can effectively reduce the interference of magnetic field distributionon the measuring signal.4. The design and optimization of Type IV micro-hotplateThe new micro-hotplate with electrodes and substrate structure is designed andoptimized, its size is1.23mm×1.23mm×300μm. The thermal field and magneticfield are analyzed by using the finite element analysis software ANSYS, in order tomake the Type IV micro-hotplate get the best temperature distribution, the thicknessof electricity insulation layer(SiO2), substrate(Si), thermal insulation layer(SiO2) are 35μm、115μm、150μm, the heating width is60μm, the measuring electrode width is10μm and without interdigitated structure. The temperature in the center of themicro-hotplate is336.335℃,and evenly distributed. Through the analysis, themagnetic field in the center of the micro-hotplate is minimum and uniform, the valueof8.31×10-7A/m, compared with the maximum of magnetic field (385.363A/m), themagnetic field in the center of the micro-hotplate can be ignored, it can effectivelyreduce the interference of magnetic field distribution on the measuring signal.5. The comparison of micro-hotplates Type I,II,III and IVWith the same power consumption, the four micro-hotplates obtain the uniformtemperature distribution in the center, and the type I micro-hotplate gets the highesttemperature in the center with the value of350.32℃, followed by Type III, II and IV.The magnetic field in the center of the four micro-hotplates is uniform and minimum.The magnetic field in the center of the type II is the minimum with the value of2.19×10-7A/m, followed by Type III, IV and II.