Nanocomposite-Enhanced Iontronic Tactile Sensor With High Sensitivity and Wide-Range Linearity for Underwater Robotic...

Hydrostatic preload increases response nonlinearity and limits weak-force detection in underwater tactile sensing. Here, we present a nanocomposite-enhanced iontronic tactile sensor (NeITS) that combines high sensitivity with wide-range linearity through a coupled mechano-ionic mechanism. Hydrophobic SiO₂ nanoparticles reinforce the ionogel, suppress premature geometric saturation, and sustain contact-area evolution, while pressure-driven interfacial ion enrichment enhances electric double-layer capacitance. The optimized sensor achieves a sensitivity of 55.36 kPa^{─ 1} over a 500 kPa linear range, with response and recovery times of 50 ms. It resolves an additional contact pressure of approximately 2 kPa at hydrostatic preloads of 0, 93, and 116 kPa with closely comparable response amplitudes. A 4 × 4 NeITS array enables real-time pressure mapping and shape imaging. Integrated into an underwater robotic gripper, the array supports neural-network-assisted recognition of nine representative benthic biological targets, achieving a mean classification accuracy of 97.8% under temporally separated window-level evaluation. This work establishes a materials-level strategy for hydrostatic-pressure-tolerant iontronic sensing and advances tactile perception for underwater robotic manipulation.