Multilayer Dielectric Elastomer Actuator with Enhanced Breakdown Strength via Regulating the Layer Thickness Ratio

Dielectric elastomers, characterized by their rapid response speed, large actuated strain, and high energy density, presented significant advantages in the realm of flexible actuators. Enhancing the breakdown strength of dielectric elastomer actuators is crucial for ensuring actuated stability and achieving higher strain at elevated voltages. In this work, the theory of bilayer electric field redistribution was further investigated to guide the structural design of multilayer dielectric elastomers. The 11-layer (MWCNT-Ecoflex)/Ecoflex composites with tailorable insulating layer/polarization layer thickness ratios (<i>r</i>) were prepared by alternately stacking the insulating layer (Ecoflex) and the polarization layer (MWCNT-Ecoflex). We theoretically and experimentally demonstrated that increasing the layer thickness ratio (<i>r</i>) between the insulating layer (characterized by a low dielectric constant) and the polarization layer (exhibiting a high dielectric constant) can enhance the breakdown strength of multilayer dielectric elastomers. When the layer thickness ratio was 3.31, (MWCNT-Ecoflex)/Ecoflex composites exhibited an actuated strain of 22.79% at 13.6 MV m^-1.