Soft Robots With Reconfigurable and Deactivatable Endoskeloton

Soft robots have been attracting great attention for high flexibility and versatility. One of the most significant shortcomings of soft robots is their low bending stiffness due to the intrinsic soft nature of their body. Therefore, as their aspect ratio increases (e.g. long and slender), they have difficulty in maintaining their shape due to gravity. To address this inherent drawback, here we present a soft robot with deactivatable endoskeleton. It consists of a soft elastomeric body reinforced internally with a rigid shape memory polymer (SMP) skeleton. Exploiting tunable viscoelasticity, the stiffness of the SMP skeleton can be varied from ~1 MPa to ~1 GPa by resistive heating through an embedded liquid metal channel. At room temperature, the rigid SMP skeleton provides structural stability, making it possible for a large-scale soft robot to maintain its shape against gravity as vertebrates do. When flexible soft robotic actuation is needed, resistive heating is applied to soften the SMP, thereby deactivating the SMP endoskeleton to render the soft robot flexible and pneumatically actuatable. Furthermore, the SMP allows the soft robot to be reconfigured into different shapes. We demonstrate a large-scale gripper composed of three soft robotic limbs with an aspect ratio of 15:1. Reconfigurable and deactivatable endoskeleton may expand the applications of soft robots to diverse practical and industrial uses.

Soft robots have been attracting great attention for high flexibility and versatility. One of the most significant shortcomings of soft robots is their low bending stiffness due to the intrinsic soft nature of their body. Therefore, as their aspect ratio increases (e.g. long and slender), they have difficulty in maintaining their shape due to gravity. To address this inherent drawback, here we present a soft robot with deactivatable endoskeleton. It consists of a soft elastomeric body reinforced internally with a rigid shape memory polymer (SMP) skeleton. Exploiting tunable viscoelasticity, the stiffness of the SMP skeleton can be varied from ~1 MPa to ~1 GPa by resistive heating through an embedded liquid metal channel. At room temperature, the rigid SMP skeleton provides structural stability, making it possible for a large-scale soft robot to maintain its shape against gravity as vertebrates do. When flexible soft robotic actuation is needed, resistive heating is applied to soften the SMP, thereby deactivating the SMP endoskeleton to render the soft robot flexible and pneumatically actuatable. Furthermore, the SMP allows the soft robot to be reconfigured into different shapes. We demonstrate a large-scale gripper composed of three soft robotic limbs with an aspect ratio of 15:1. Reconfigurable and deactivatable endoskeleton may expand the applications of soft robots to diverse practical and industrial uses.