A Novel Wall-Shear Stress Sensor with A Covering Floating Element for Harsh Environment

This work reports the design, fabrication and characterization of a novel wall-shear stress sensor with a covering floating element for skin friction measurements in harsh aerodynamic applications. Sensing structures (e.g. comb fingers and folded tethers) of the sensor are settled under the protection of top-layer floating element, which avoids them from contacting micro-dusts or other pollution in measured flow. A DSOI (Dual Silicon-On-Insulator) wafer is used to develop the floating element, whose top-layer silicon (5 μm in thickness) is fabricated to sense wall-shear stress and protect underneath structures as well. As a result, possibilities of the sensor to be damaged in practical applications can be reduced as low as a hundred times. The static sensitivity of wall-shear stress sensor is calibrated as 16.27 mV/Pa, with a full-scale non-linearity of 1.8%. Meanwhile, the sensor is capable of capturing fluctuating wall-shear stress during transitional process, reveling further information for laminar-to-turbulent flows.