Development and Manufacturing of Dielectric Elastomer Actuators via Material Extrusion

This Doctoral thesis presents the potential of Additive Manufacturing (AM) in the field of Dielectric Elastomer Actuators. The first fully 3D printed uni-morph dielectric elastomer actuator (DEA) was manufactured using fused filament fabrication (FFF), also classified as filament-based Material Extrusion (MEX). The study demonstrates that commercially available FFF 3D printers and filaments can be utilized to fabricate functional DEAs without requiring modifications to the printing process. A key contribution of this research is the identification of optimal FFF 3D printing parameters for DEA fabrication, ensuring uniform dielectric membrane properties and reliable actuator performance. To achieve this, different membrane thicknesses and layer configurations were evaluated. The results showed that a 0.15 mm dielectric layer, consisting of three layers of 0.05 mm each, provided the best balance between dielectric properties and mechanical behavior. Electrode optimization was further investigated to enhance actuator performance. Through a systematic design of experiments, it was determined that an electrode infill density of 40 % and an electrode infill orientation of 90 degrees resulted in the maximum actuator displacement of 91 % relative to its free length. These results were validated through both experimental testing and simulations, which provided deeper insights into the relationship between electrode structure and the resulting electric field distribution. The findings highlight the substantial impact of electrode geometry on the efficiency and reliability of 3D printed DEAs, offering valuable guidelines for future electrode designs. Building on these developments, a more complex soft dielectric assembly was designed in the form of a fully 3D printed three-finger soft gripper. By incorporating a third material into the FFF 3D printing process, the study successfully fabricated a soft dielectric actuator assembly with integrated structural support. Given the widespread availability of FFF machines, this approach enables the production of user-customized actuators that are both easily accessible and cost-effective. The combination of dielectric elastomers and structural components in a single multi-material print highlights the potential of this method for future applications in soft robotics, where integrated functionality and flexibility are critical. Furthermore, this study introduces the first lockable DEA, manufactured using FFF, with external and intrinsic heating, utilizing shape memory polymer (SMP) filaments to enable reversible actuation locking. Experimental validation confirmed the actuator’s ability to maintain its deformed state without continuous electrical input. The integration of an SMP-based locking mechanism represents a significant advancement in DEA design, addressing a major limitation of previous actuator concepts. The concept was patented, marking a novel contribution to DEA manufacturing by enabling a single multi-material 3D-printed actuator with embedded locking functionality. To summarize, this PhD thesis highlights the potential of the FFF process for the fabrication of fully 3D-printed dielectric elastomer actuators. Suitable printing parameters for dielectric membranes and electrodes were identified, and their influence on actuator performance was analyzed. Additionally, a fully 3D printed soft dielectric gripper was successfully fabricated, demonstrating the feasibility of integrating actuation and structural support within a single print. Finally, a lockable DEA with external and intrinsic heating was developed and validated, introducing new functionalities in fully 3D printed DEAs technology. These findings establish a strong foundation for future advancements in soft robotics and additive manufacturing, showcasing the potential of FFF technology for accessible and customizable soft dielectric actuators.