用于壁面切应力测量的微传感器设计

Design of Micro Sensor for Wall Shear Stress Measurement

壁面切应力的测量是流体动力学领域中一项非常重要的测试任务,采用MEMS技术设计、加工的微型切应力传感器能够为壁面切应力的测量提供新的手段。微传感器设计过程中推导其浮动单元线性位移与弹性梁宽度的关系,通过限位装置提高了微传感器的抗过载能力。有限元仿真结果与试验模态分析的最大偏差为8.2%,表明仿真过程中对结构进行的简化以及单元的选取是合理的。加工过程中,采用等离子刻蚀工艺形成传感器的结构,湿法刻蚀工艺完成浮动单元的释放,所加工传感器的整体尺寸为3.4 mm×2.5 mm×0.6 mm。开发了一种封装结构实现传感器与壁面的平齐安装。风洞试验结果说明在0～30 m/s风速范围内传感器的灵敏度为51.2 mV/Pa,该传感器可以用于壁面切应力的测量。

The measurement of wall shear stress is an important task in fluid dynamics.The micro shear stress sensor which is designed and fabricated by using MEMS technology can supply a new method for this measurement.During the process of design,the relationship between the linear displacement of floating element and the width of elastic beam is deduced.The caging devices are designed to improve the overload capability of the micro sensor.The maximum deviation of finite element simulation results from the experimentally determined modes is 8.2%,indicating that the simplification of the structure and the types of elements are reasonable.During the process of fabrication,plasma etching technology is used to form the sensor structure,and wet etching technology to accomplish the release of floating elements.The dimension of the micro sensor is 3.4 mm×2.5 mm×0.6 mm.A special package is used to realize flush-mounting between the sensor and the wall.The wind tunnel test result shows that in the wind speed of 0～30 m/s,the sensor sensitivity is 51.2 mV/Pa.The micro shear stress sensor can be used to measure the wall shear stress.