Controllable Stiffness Origami “Skeletons” for Lightweight and Multifunctional Artificial Muscles

Abstract

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.

Optimization of Phase-Change Material–Elastomer Composite and Integration in Kirigami-Inspired Voxel-Based Actuators

“…In previous work, reconfigurable robots capable of locomotion have been built by assembling pneumatically actuated voxels able only of contraction and expansion Zou et al (2018) , Sui et al (2019) . Lin et al designed more complex and versatile soft robots, using bending and contractile pneumatic voxels Lin et al (2020) , but requiring an important amount of pressure lines and complex pressure signals. The heat-actuated fixed kinematic voxels presented in this work compromise among the design simplicity, ease of actuation, and the loss of reconfigurability of the voxels.…”

Programmable Stimuli-Responsive Actuators for Complex Motions in Soft Robotics: Concept, Design and Challenges

“…Elastomers (Ecoflex [6][7][8][9][10][11][12][13][14][15][16], Dragon Skin [17], Sylgard 184 [18,19], other [20][21][22][23][24][25]), fabric [15,26,27], Filaflex [28], hydrogels [29], Diels-Alder polymer [30], polypropylene [31], FC72 fluid [24], ethanol [16], paper [32], urethane [27], gelatin-based biogel [33] Phase Change Material Elastomer Composite (PCMEC) Elastomers [34][35][36], phase change material (wax [35], ethanol [34])…”

“…Ze et al [74] used a custom SMP with stiffness varying between 2.4 MPa and 2.9 GPa in a similar temperature range. Finally, granular or layer jamming is another common tunable stiffness solution [12,32]. When a vacuum is applied on a granular medium or on a stack of layers (e.g., paper [32]), the friction forces between the grains/layers increase, leading to a higher stiffness.…”

“…Finally, granular or layer jamming is another common tunable stiffness solution [12,32]. When a vacuum is applied on a granular medium or on a stack of layers (e.g., paper [32]), the friction forces between the grains/layers increase, leading to a higher stiffness. This solution presents the advantage of being fast, but the stiffness change is generally more limited compared to material-based solutions [155].…”

“…As illustrated in Figure 7m, a variable stiffness layer can be added to control the actuation behaviour of a transducer and to lock it in the actuated configuration [25] (orange layer in the bottom of the schematic). A similar principle can be applied for the other basic kinematics [32]. Variable stiffness can be used to control the actuator kinematics by reducing the stiffness of a given point or segment of an actuator, which will consequently deform under the transducer action [75,159].…”