Temperature Sensitivity Reduction of a Capacitive Wall Shear Stress Sensor System for Low-Speed Wind Tunnels – AIAA Jan 2021

This paper describes the development and experimental characterization of a temperature-compensated wall shear stress sensor system designed to reduce temperature sensitivity and be non-invasive to low-speed aerodynamic flows. The differential capacitive microelectromechanical systems (MEMS) sensor is fabricated using a novel, low-cost approach to creating backside electrical contacts, creating a hydraulically smooth surface without the use of through-silicon vias. Temperature compensation in the form of a thermistor provides a greater than 10x reduction in temperature sensitivity, thus increasing the accuracy of mean shear stress measurements in flow environments where the temperature is not held constant. Characterization of a 5 kHz bandwidth, 300 Pa temperature-compensated shear stress sensor system yields a sensitivity of 35.3 mV/Pa at 1 kHz, minimum detectable signal of 0.13 mPa/rtHz, and a temperature sensitivity of 77 mPa/degC, a ~32x reduction compared to previous-generation devices.

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