Controllable Stiffness Origami "Skeletons" for Lightweight and Multifunctional Artificial Muscles

Flexible, material-based, artificial muscles enable compliant and safe technologies for human-machine interaction devices and adaptive soft robots, yet there remain long-term challenges in the development of artificial muscles capable of mimicking flexible, controllable, and multifunctional human activity. Inspired by human limb's activity strategy, combining muscles' adjustable stiffness and joints' origami folding, controllable stiffness origami "skeletons," which are created by laminar jamming and origami folding of multiple layers of flexible sandpaper, are embedded into a common monofunctional vacuumed-powered cube-shaped (CUBE) artificial muscle, thereby enabling the monofunctional CUBE artificial muscle to achieve lightweight and multifunctionality as well as controllable force/motion output without sacrificing its volume and shape. Successful demonstrations of arms self-assembly and cooperatively gripping different objects and a "caterpillar" robot climbing different pipes illustrate high operational redundancy and high-force output through "building blocks" assembly of multifunctional CUBE artificial muscles. Controllable stiffness origami "skeletons" offer a facile and low-cost strategy to fabricate lightweight and multifunctional artificial muscles for numerous potential applications such as wearable assistant devices, miniature surgical instruments, and soft robots.