Drastic breakdown field reduction in multilayer DEA

The electrical properties such as the electrical breakdown and the permittivity but also the softness of the elastomer are key factors for the performance of DEA. In order to have the best use of elastomer films, single-layer actuators have been deeply studied, regarding the breakdown and its dependence on the stretch and on the thickness. Multilayer DEAs boost the volume of active material, without any voltage or surface increase. Such multilayer structure is mandatory to achieve high power actuator. Nevertheless, our experiments show a significant reduction of the breakdown field when multilayer configuration are used. Whatever the film thickness staked in the multilayer DEA (200 or 100 micrometers) the breakdown voltage is half the one obtained for single layer. Various factors could explain this discrepancy. A careful analysis of breakdown location in several configurations suggest electrical field concentration at edges of the electrode, as possible cause for this unusual low breakdown field. Even if the numerical simulations suffer from a lack of data on conduction phenomena in the elastomer, it shows the key role of the air in the reduction of the field concentration in single layer structure. Different breakdown mechanisms, such as the electromechanical instability or the electrothermal, have already been pointed out. This work brings up that the field concentration at edges is a tremendous limiting factor of multilayer DEA.