Dielectric elastomer actuators as artificial muscles for wearable robots

Abstract

Current powered prosthetic and orthotic devices are mostly based on rigid actuators, which exhibit some intrinsic limitations, such as the reduced number of degrees of freedom, high weight, and limited flexibility. As progress is made in the soft robotics field, artificial muscles arise as potential candidates to replace current rigid actuator technologies. Dielectric elastomer actuators (DEAs) are a very promising class of soft actuator and are attracting attention due to their high energy density, fast response, and high actuation strains, similar or even superior to natural muscles. Such remarkable properties can lead the DEAs to be the next generation of actuators for wearable robots, and overcome the limitations imposed by the rigid actuators currently used. This paper reviews the state of art of the applications of DEAs to prostheses, orthoses, and rehabilitation devices. We analyzed the main configurations that are suitable as artificial muscles for the above-mentioned applications and presented the basic model of a dielectric elastomer transducer. When compared to the properties of natural skeletal muscle, some of these configurations stand out. However, there are still some drawbacks that prevent the large-scale application of DEAs, for instance the high operating voltages, durability issues, and nonlinearities that make them difficult to control. We investigated recent advances in materials, control strategies and fabrication methods that tackle these drawbacks, and they indicate that dielectric elastomers are great candidates to be the next generation of actuators for bionic devices.

Exploring stimuli-responsive elastin-like polypeptide for biomedicine and beyond: potential application as programmable soft actuators

“…Due to these electromechanical properties, PVDF has been one of the most investigated EAPs for actuators. Dielectric elastomers such as polysiloxane are also widely used because of their flexibility and mechanical compliance allowing larger strain Novelli et al (2023) . For the actuator to deform freely in all directions, the electrode also must be flexible enough to undergo similar shape deformation.…”

Design and Force/Angle Independent Control of a Bionic Mechanical Ankle Based on an Artificial Muscle Matrix

“…In recent decades, a large number of scholars have conducted, and are still conducting, research on imitating the form and function of skeletal muscles. Different types of actuators have been put forth and extensively studied for their potential applications as “artificial muscles” [ 2 ], including traditional actuator devices (such as electric motors [ 3 , 4 ], hydraulic actuators [ 5 , 6 , 7 , 8 ] and pneumatic actuators [ 9 , 10 , 11 , 12 ]) and smart materials (such as electroactive polymers [ 13 , 14 , 15 , 16 ], high-strength polymer fibers [ 17 ], magnetostrictive alloys [ 16 ] and shape memory alloys [ 1 , 2 , 18 , 19 , 20 ]).…”

Network Formation, Properties, and Actuation Performance of Functionalized Liquid Isoprene Rubber

“…To the best of our knowledge, no previous study has reported on the use of liquid isoprene rubber and the opted cross-linking chemistry to develop an electronically deformable elastomer for soft actuator applications. ,− …”