Multilayer Dielectric Elastomer Actuators: Processing and Characterization in an Out-of-Plane Actuator Configuration

Dielectric elastomer transducers exhibit extraordinary actuator properties due to their huge actuation, small construction volume and low energy consumption. Dielectric elastomer actuators (DEA) consist of a thin dielectric elastomer (DE) film covered with stretchable electrodes on both surfaces. If a high voltage is applied, the electrodes attract each other which leads to a reduction of the elastomer film thickness and due to the incompressibility of the elastomer film to an actuator area enlargement. Based on extensive developments, a variety of actuator forms are standard in research and, in some cases, in application. With special designs, such as out-of-plane actuators, dielectric elastomer actuators are able to transmit larger forces with deflections in the range of around one millimeter. Here, we present the fabrication and characterization of DE multilayer actuators as well as their embedding in out-of-plane actuators. In detail, the multilayer actuator consists of eight elastomer layers with thicknesses of 100 mu m each and electrode widths of 30 mm and lengths of 50 mm or 80 mm. The developed multilayer actuators provide in-plane deflections of about 2% and out-of-plane deflections of about 400 mu m and 800 mu m for actuators with lengths of 50 mm and 80 mm, respectively, when operated with an electric field of 50 MV/m. The out-of-plane multilayer actuators exhibiting a blocking force of e.g. 1.8 N at an electric field of 70 MV/m. In order to describe the actuator behavior, an analytical model based on the neo-Hookean hyperelastic material model is developed. The comparison of the calculated and experimental data shows a good agreement for the in-plane investigations of the actuator multilayers and an approximate agreement for the out-of-plane actuators.