Concept and Fabrication of Silicone-based Rolled Dielectric Elastomer Actuators (RDEAs) for Soft Robots

Abstract:
In this work, we present the concept, fabrication and initial experimental evaluation of our silicone-based rolled dielectric elastomer actuators (RDEAs). In general, dielectric elastomer actuators (DEAs) consist of a dielectric, compliant film sandwiched between two electrodes. By applying a voltage to these electrodes, the electrostatic forces squeeze the film. Due to its incompressibility, the film expands in the planar directions. This behavior can be exploited to produce electromechanical actuators. In the application of soft robotics, soft and compact actuators with high energy densities are required. RDEAs offer an ideal solution. They offer characteristics similar to human muscles in terms of energy density and bandwidth. Each RDEA is fabricated by screen printing an electrode of conductive and flexible carbon-black-based ink onto one side of a 50micrometer thick silicone-film (Wacker Elastosil 2030). Two of those films are stacked and rolled in a spiral-like configuration. A combination of wire ferrules and threaded nylon rods are used as mechanical and electrical interfaces. At first, the components of the system are analyzed and an appropriate concept for each of them is presented. Afterward, the manufacturing process is outlined. One notable challenge was the development of a process that prevents wrinkling and undesired sticking of the film to itself. Finally, an experimental evaluation of mechanical and electrical characteristics of the developed RDEA is performed. Our measurements show a change of blocking force of 0.18 N under constant load conditions and we predict a stroke of 2.5 % at 2 N.