Artificial Whisker Sensor with Undulated Morphology and Self-Spread Piezoresistors for Diverse Flow Analyses

Harbor seal whiskers possess an undulated surface morphology that can effectively modify the vortex street behind the whiskers and suppress vortex-induced vibrations (VIVs). In this study, we propose a novel piezoresistive flow sensor that mimics the function of seal whiskers. The sensor consists of a bionic whisker with an undulated morphology and integrated out-of-plane piezoresistors. The piezoresistors are formed using a novel directional liquid spreading method to deliver a conductive nanocomposite ink into four Ω-shaped microchannels. Steady flow experiments indicate that the undulated morphology of the artificial whisker significantly reduces the drag forces and VIVs of the whisker at an angle of attack of 0°. Moreover, the whisker sensor can measure the oscillatory flow, which reaches a threshold detection limit of 8 mm/s. In addition, we demonstrate the function of the artificial whisker sensor to distinguish various wakes induced by upstream cylinders. Therefore, the facile fabrication and preliminary experiments of the artificial whisker sensor demonstrate its potential application in diverse flow analyses.