A Bio-Inspired Whisker Sensor toward Underwater Flow Sensing in Darkness and Turbidity

Abstract: Underwater flow sensing is critical for unmanned underwater vehicles (UUVs) and environmental monitoring, yet existing sensors often suffer from low responsiveness, high detection thresholds, limited directional discrimination, complex packaging, and poor long-term stability, especially for navigation and target perception in turbid and cluttered waters. Previous solutions based on traditional strain gauges with limited detection accuracy or doped silicon sensors with limited detection height have shown feasibility but still face challenges in scalability, robustness under harsh aquatic conditions, and calibration complexity. This work presents a bio-inspired whisker sensor that provides a balanced solution by embedding high-gauge-factor silicon strain gauges into a flexible PDMS base, mimicking seal whiskers to offer both high sensitivity and simplified packaging. The device exhibits a linear force-resistance response with a limit of detection of 0.27 mN, maintains stability after 10,000 loading cycles, and shows minimal offset drift of less than 2 percent. It also demonstrates frequency matching in underwater dipole tests with clear longitudinal and transverse spatial response patterns. These results indicate a robust and scalable route for underwater flow sensing on UUV platforms in practical deployments.