Multiscale-structured miniaturised 3D force sensors

Flexible tactile sensors are pivotal for advancing neuroprosthetics, human-machine interaction, 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 multi-scale 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 surpasses 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.