A Fully 3-D-Printed Piezoresistive Bionic Seal Whisker Integrating Multiple Liquid Metal Tunnels for Enhanced Sensitivity in Hydrodynamic Flow Sensing

Abstract

Fish use their lateral line organs to sense wake changes in the flow field environment to conduct hunting, avoidance, and communication activities. Seals efficiently enhance their sensitivity to prey’s wake-induced vibrations (WIVs) by suppressing vortex-induced vibrations (VIVs) with undulating whiskers. In this study, we proposed a fully 3-D-printed piezoresistive bionic flow sensor. The bionic whisker simulates the geometrical dimensions of a real gray harbor whisker. The piezoresistive sensing unit made of liquid metal simulates the synaptic electromechanical transitions of hair follicle cells to acquire flow field information. Uniform flow field experiments and simulation results revealed that the sensor can effectively suppress VIVs at an angle of attack (AOA) of 0° and achieve a minimum flow velocity of 0.03 m/s at AOA of 90°. The sensing unit’s directional arrangement realizes the discrimination of the flow direction. In addition, the sensor demonstrated to determine the wake generated by the upstream cylinders and direct information about the upstream cylinders. Therefore, the sensors’ experimental results of the bionic whisker sensor can be applied to underwater robots to perceive diverse flow field information.