Fabrication technologies for the electrode structure of a dielectric elastomer bending tube actuator

A new concept for a tube-like dielectric elastomer actuator (DEA) utilizes rigid micro-electrodes to stabilize the tube structure in azimuthal direction. A number of those electrodes are electrically and mechanically interconnected and fully embedded into a silicone layer. Those electromechanical networks represent individual actuator groups. An axial arrangement of a number of those electrode groups forms a single actuator filament. Applying an electrical voltage induces mechanical tension into those electrode groups by the effect of Maxwell-stress. The interaction of individual electrodes causes a change of the total length of selected actuator filaments. A circular arrangement of a number of actuator filaments allows bending of the tube in any direction. The electrode thickness appears as passive non compliant parameter within the axial length of an actuator filament. The desired tube actuator is focused on thin walled structures with an outer diameter less than 6 mm and an available width of the wall of less than 0.4 mm. The challenge for the fabrication of this electrode structure is mainly based on the elastic properties of the 2K-silicone substrate, unfavourable adhesion characteristics of the silicone, a desired minimal electrode thickness of less than 5 microns and a required homogeneon electrode body. The present work introduces the tube-actuator concept and details fabrication concepts for the embedded electrode structure considering actuator-related electrical and mechanical requirements.