Beyond Planar: Enhanced Performance of Hollow Fiber Dielectric Elastomer Actuators.

Hollow fiber dielectric elastomer actuators (HFDEAs) offer several advantages over their conventional counterpart, planar dielectric elastomer actuators (DEAs). Due to their simple shape, flexibility, and conformability, HFDEAs are promising candidates for complex applications within soft robotics. This paper offers a comprehensive comparison between the actuation behavior of planar and HFDEAs using both analytical and numerical models. An electro-mechanical model establishes analytical correlations between the applied voltage and resulting strain. The results from the simplified model are subsequently compared with a numerical model in COMSOL Multiphysics, where simulations are run in more realistic conditions. Supporting experiments are conducted on HFDEAs with different geometries to validate the model. A geometric factor, β, is introduced to account for the influence of geometric parameters on actuator performance. The results show that HFDEAs exhibit higher strain compared to planar films. Among the different fiber geometries, those with smaller internal diameters and thinner walls exhibit higher axial strain and holding force while using the least amount of material. This study highlights the advantages of hollow fiber DEAs compared to their planar counterparts, especially in applications where lighter, more efficient structures with greater strain capabilities are essential.