Nanocomposite‐Enhanced Iontronic Tactile Sensor With High Sensitivity and Wide‐Range Linearity for Underwater Robotic Manipulation

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 SiO 2 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.