Multiscale-structured miniaturized 3D force sensors.

Flexible tactile sensors are pivotal for advancing neuroprosthetics, human-machine interactions and intelligent robotics. However, achieving highly sensitive tactile sensing to differentiate normal and tangential forces, particularly in mimicking the high-resolution multidimensional haptics of human fingers, remains a challenge. Here we propose a triaxial force microsensor array made from graphene-liquid-metal composites. Using anisotropic particle networks in microporous composites with pyramid geometries, we achieve normal-tangential force decoupling through multiscale structuring. Our approach offers exceptional sensitivity of 110 kPa-1 over a 500 kPa linear range (R2 > 0.998), with <2° force direction measurement deviation. The sensor array demonstrates force decoupling and slip detection via self-adjusted grasping of unknown objects. Our microsensor improves on the state of the art by an order of magnitude in size and detection limit, enabling 3D force sensing in micromanipulators and microrobots and unlocking advanced robotic dexterity.