Design of micro sensor for wall shear stress measurement

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.