Bioinspired bicipital muscle with fiber-constrained dielectric elastomer actuator

Dielectric elastomers have become promising candidates for applications of artificial muscle, due to their outstanding properties on large deformation, fast response and high energy density. Diverse functional devices based on dielectric elastomer actuators have been developed. To mimic a slender shape muscle-like actuator with the capability of large actuation, however still remains a challenge. The fiber constrained dielectric elastomer actuator (FCDEA) was previously presented but only 30% unidirectional actuation strain was obtained. In this work, By using suitable stiff fibers to withstand large horizontal pre-stretch, up to 142% linear actuation strain is achieved. We demonstrate that the actuator is independent of the length ratio, making it possible to mimic natural muscle of slender shape. Theoretical predictions agree remarkably well with the experimental results. As a demonstration, we incorporate the FCDEA into a bioinspired artificial arm. After applying voltage, 70 degree rotation is achieved for the forearm relative to the fixed upper arm. The bioinspired design with the unique properties of dielectric elastomers shows the potential to use FCDEA to function as artificial muscle.