Einstellung anisotroper Eigenschaften dielektrischer Elastomersysteme mittels eines selektiven Druckverfahrens

Description

Modern mechatronic systems often try to mimic biological principles to improve functionality. As a result, soft components are becoming increasingly important, but are lacking in terms of performance or portability. In this thesis, the isotropic motion of dielectric elastomers is adapted to an anisotropic behaviour, following a bionic design approach. To achieve this, an additive manufacturing technology is used that allows a defined and heterogeneous distribution of electrically conductive particles. A segmented electrode design is being tested for the actuators, while the sensors are based on heterogeneous particle clusters. As a result, the electromechanical coupling of the electrode segments of dielectric elastomer actuators leads to anisotropic motion, revealing an inverse correlation between the anisotropy ratio and the maximum uniaxial displacement. In particular, the special case where all the electrodes are rim electrodes shows advantageous anisotropic properties. For dielectric elastomer sensors, the heterogeneous particle distribution allowed the detection of force amplitude and direction. A linear correlation between electrode resistance and applied strain can be found for small deformations. Whereas the magnitude of the linear range depends on the path distance. The relevance of the results is demonstrated by two practical examples. As a functional iris implant, the diaphragm expansion can be increased due to the anisotropic design of the electrode segments. Furthermore, the defined heterogeneity of an anisotropic sensor allows the complete characterisation of wrist movements. In this first description printed anisotropic electrodes in dielectric elastomers are used as conventional membrane actuators. Further improvements are expected by implementing alternative designs or pre-stretching.
Die Bedeutung der Ergebnisse wird anhand von zwei praktischen Beispielen verdeutlicht. Als funktionelles Irisimplantat kann die Ausdehnung durch die anisotrope Gestaltung erhöht werden. Weiterhin ermöglicht ein anisotroper Sensor die vollständige Charakterisierung von Handgelenksbewegungen. In dieser Dissertationsschrift werden gedruckte anisotrope Elektroden als konventionelle Membranaktoren verwendet, wobei weitere Verbesserungen durch alternative Aufbauformen oder Vordehnung erwartet werden.