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采用MEMS技术加工的底层隔板能够为壁面剪应力的测量提供新的手段。利用有限元法(FEM)建模仿真、正交实验设计以及各因素的极差分析,考查了微敏感结构宽度、厚度和凸出壁面高度对底层隔板固有频率和压阻灵敏度的影响规律,完成了底层隔板的结构优化设计。仿真结果显示:微敏感结构厚度对隔板固有频率和灵敏度影响最大,提升敏感结构高度能够有效提高压阻灵敏度,固有频率和压阻灵敏度受微敏感结构宽度变化影响很小。基于绝缘体上硅技术,利用电感耦合等离子体刻蚀工艺形成底层隔板结构,反应离子刻蚀工艺完成对敏感结构的释放,所加工底层隔板的整体尺寸为5.9mm×10.1mm×0.39mm。底层隔板的动态特性测试表明样件固有频率为1 453.1Hz,与有限元仿真结果的最大偏差为4.4%。
The use of MEMS technology, the bottom of the separator can provide a new measure of wall shear stress. The finite element method (FEM) modeling and simulation, orthogonal experimental design and the range analysis of each factor were used to investigate the effects of the width and thickness of the microsensitive structure and the height of the protruding wall on the natural frequency and piezoresistive sensitivity of the bottom separator. Completed the structural optimization of the bottom partition design. The simulation results show that the thickness of the micro-sensitive structure has the greatest influence on the natural frequency and sensitivity of the bulkhead. Improving the height of the sensitive structure can effectively increase the piezoresistive sensitivity. The natural frequency and the piezoresistive sensitivity are less affected by the change of the width of the micro-sensitive structure. Based on the silicon-on-insulator technology, the bottom spacer structure is formed by an inductively coupled plasma etching process, and the release of the sensitive structure is completed by the reactive ion etching process. The overall size of the bottom spacer is 5.9 mm × 10.1 mm × 0.39 mm. Dynamic characteristics of the bottom partition test showed that the sample natural frequency of 1 453.1Hz, and the finite element simulation results of the maximum deviation of 4.4%.