Publication
Dielectric Elastomer Actuators (DEAs) are a recent type of smart materials that show impressive performances as soft actuators and that have become new references when developing soft artificial muscles. Implementing dielectric elastomer actuators (DEAs) that mimic natural muscles has been proven difficult, as DEAs provide in-plane expansion when actuated, while natural muscles contract upon stimulation. Multiple solutions can be found in literature, namely stack DEAs and fiber reinforced DEAs. However, for thin artificial muscles, a stacked actuator inducing a contraction movement is challenging due to the space available; a planar actuator configuration can thus be considered by embedding fibers. Embedding fibers within the DEA allows to alter the DEA mechanical characteristics in order to obtain an anisotropic movement, notably a movement of contractile nature similar to biological muscles. The fibers resist length change while remaining flexible in bending, which can be useful for various applications. It is thus possible for DEAs to create planar contraction when compressed through the thickness due to orientation of the fibers. Currently, the fibers used for DEAs to achieve contractile motion rely on a fishnet design, where the angle between the fibers, the spacing, mechanical properties as well as the fiber dimensions can be set by establishing a fiber analytical model, characterized by hyper-elastic anisotropic models for reinforced DEAs. Contractile DEAs can be fabricated by embedding different fiber materials, both active and passive, and varying the mesh angle and applied loads.