Design of liquid metal bionic sensors for decoupling multi-degree-of-freedom deformation in soft robots

Abstract The efficient environmental interaction of soft robots relies on multi-degree-of-freedom deformation perception capabilities compatible with their bodies. However, existing flexible sensors generally face the challenges of difficult multi-modal strain decoupling and complex manufacturing processes. Inspired by the multi-layer perception mechanism of human skin, this paper designs a bionic double-layer liquid metal sensor. Its upper and lower layers adopt spiral and orthogonal micro-channels, respectively, and are precisely manufactured through 3D printing technology, aiming to sensitively decouple bending and compressive strains. The experimental results demonstrate that the sensor achieves a high sensitivity of 2.83, an excellent linearity with a correlation coefficient of 0.99, and an exceptionally low hysteresis of 0.73%. With a rapid response time of 63 ms, the sensor exhibits remarkable durability under repeated cyclic testing. In application verification, the pneumatic soft gripper integrated with this sensor can distinguish the shape and hardness of the grasped objects in real time. This work not only provides an effective biomimetic solution to the problem of multi-degree-of-freedom deformation perception in soft robots, but also lays a solid foundation for the development of high-performance soft sensing systems with its integrated design framework of ‘structure-manufacturing-decoupling’.