AeroMEMS Sensor with Integrated Pressure and Hot-Wire Sensor for High-Frequency Transition Detection

Abstract

A novel AeroMEMS sensor featuring integrated pressure and wall hot-wire sensor is presented. The sensor consists of a highly sensitive piezoresistive pressure sensor exhibiting a sensitivity of 4.5 µV/(VPa) and a wall hot-wire composed of aluminum (AlSiCu) that is thermally insulated by an air-filled cavity. Thus, the sensor makes combined wall pressure and wall shear stress measurements possible. Integration of sealed through silicon vias enables to electrically contact the sensor chips from the back side. Hence, flow disturbing bond wires on the front side are avoided when chips are mounted flush with the measured surface. High-frequency laminar-turbulent transition measurements are conducted employing a linear sensor array consisting of 24 chips that is integrated in a wing profile and tested in a transonic wind tunnel. Transition showing frequencies up to 9.5 kHz is measured at a Mach number of 0.32. Furthermore, the first harmonic featuring a frequency of 18 kHz is detected with both measurement principles. The sensor’s excellent dynamic properties and its potential of simultaneously measuring wall pressure and wall shear stress makes the device a powerful measurement tool for fluid mechanics.