Geometry-driven multimodal tactile sensors with high-fidelity perception enabled by strain-invariant oxidized liquid metal electrodes.

Multi-axis tactile sensors that simultaneously resolve normal and shear forces are indispensable for dexterous robotic manipulation and human-robot interaction. Capacitive platforms, however, suffer from microcrack-induced resistance fluctuations in conventional electrodes, which corrupt RC time constants and degrade signal fidelity under repeated deformation. Here, we introduce a geometry-driven multimodal capacitive tactile sensor employing oxidized liquid metal (O-LM) electrodes whose near-invariant conductivity eliminates this instability. An anisotropically offset 2 × 2 capacitor array decouples normal and shear components through purely geometric means, while a micro dome-pyramid hierarchical dielectric architecture yields a sensitivity of 3.14 × 10-3 kPa-1 over a 0-160 kPa range. Integrated onto a robotic gripper, the sensor enables real-time three-axis force mapping during object grasping and dynamic manipulation, demonstrating that a geometry-driven capacitive design can achieve reliable multimodal tactile perception for practical robotic applications.