Biomimetic Fluid Sensor for Detecting Frequency-Variable Hydrodynamic Footprints

Marine aquatic bodies move with varying speeds and directions, producing complex, frequency-rich hydrodynamic “footprints”. We introduce a novel class of biomimetic fluid sensors designed to detect and differentiate these complex flow features. The sensor system includes a harbor seal whisker-inspired module mounted on a multi-tuned mass-spring base, allowing it to undergo flow-induced vibrations, serving as the primary sensing mechanism. By positioning an object upstream from the whisker, we replicate the hydrodynamic footprints produced by aquatic bodies. Unlike traditional methods that use stationary cylinders to create simple vortex patterns as a footprint, our setup employs an upstream cylinder on a high-precision linear motor stage to generate dynamic, frequency-variable footprints that better mimic a range of aquatic footprints. Our water tunnel experiments show that this biomimetic sensor effectively captures and distinguishes between various dynamic flow features. Additionally, incorporating an extra degree of freedom through the multi-tuned mass-spring base design extends the sensor's flow velocity range, while structural nonlinearity further enhances sensitivity.