Dynamic Electric Double Layer Enabled Pressure and Position Sensing for Autonomous Underwater Object Grasping

Tactile sensing plays a critical role in object grasping in visually constrained underwater environments, yet conventional electronic sensors are hindered by waterproofing challenges and vulnerability to hydrostatic pressure. Here, we introduce a self-powered tactile sensing method based on the dynamic modulation of the electric double layer (EDL) at liquid-electrode interfaces. The approach consists of a simple open-ended rubber tube filled with seawater and two embedded electrodes, requiring no external encapsulation or power supply. Upon deformation, fluid motion within the tube perturbs the EDL, generating a measurable electric potential. The signal magnitude scales with pressure, electrode surface area, and ionic concentration, while its polarity varies with the pressing location, enabling concurrent pressure and position sensing. The sensor exhibits a sensitivity of 0.07 V/kPa, a response time of 0.02 s, and maintains signal integrity with less than 10.7% attenuation under 1 MPa of hydrostatic pressure. Demonstrations of autonomous underwater grasping validate its practical feasibility. This work establishes a robust and minimalist sensing principle grounded in nanoscale interfacial electrochemistry, offering a universal strategy for self-powered tactile, soft robotic, and environmental sensing systems.