A system for vector measurement of aerodynamic wall shear stress

This paper describes a sensor system designed for vector measurement of aerodynamic wall shear stress. The microelectromechanical systems (MEMS) prototype utilizes a serpentine tether flexure for dual-axis in-plane motion. Capacitive gap pairs coupled to a multi-frequency modulation/demodulation system allow for independent transduction across both axes. Sensor performance includes an average dynamic/mean shear stress sensitivity of 0.16 mV/Pa, corresponding to a minimum detectable signal of 0.3 mPa at 1.128 kHz. Pressure rejection is calibrated at 74 dB, with in-plane cross-axis isolation in excess of 24 dB.