A MEMS wall shear stress sensor with floating cover plate for aerospace flow monitoring in harsh environments.

Abstract

Wall shear stress is one of the key parameters in turbulent boundary layers, playing a pivotal role in aerodynamic optimization and fuel efficiency enhancement. Although MEMS-based direct measurement stands as the most promising approach for wall shear stress quantification, the inherent limitations of floating sensing structures under harsh environments lead to mechanical failure, representing persistent technical barriers in practical applications. This work presents a novel MEMS sensor equipped with a protective floating cover plate, achieving high-robustness measurement through coordinated structural-process innovations. Based on the Dual Silicon-On-Insulator (DSOI) fabrication process, a protective floating configuration is developed. The critical process techniques, including deep silicon etching, wet etching of glass through vias, and silicon-glass anodic bonding synergistically establish protection for the sensing structures. The established electromechanical coupling mathematical model elucidates quantitative mapping relationships between critical structural parameters and sensing performance. Experimental characterization reveals a linear sensitivity of 28.3 mV Pa^-1 and a resonance frequency of 2.9 kHz. In supersonic tunnel experiments at Mach 2.0, the sensor achieves unprecedented full-cycle dynamic capture from establishment through stabilization to dissipation with millisecond-level transient response characteristics. This work provides a robust, high-precision solution for aerodynamic and fluid dynamics applications, paving the way for improving energy efficiency and flow control strategies.