The role of chemical microstructures and compositions on the actuation performance of dielectric elastomers: A materials research perspective

Dielectric elastomer actuators (DEAs) are one of the emerging areas of investigation in smart elastomer research and have attracted considerable interests due to their wide-ranging applications, for instance in automation and soft robotic components. Commonly utilized dielectric elastomers (DEs) such as nitrile butadiene rubber (NBR) and its hydrogenated and carboxylated derivatives along with the dielectric fillers (titanium oxide, barium titanate, etc.) were considered to be one of the most established composite systems demonstrating high actuation performance. When subjected to external electrical field, the DEAs derived from the composites were, therefore, capable of reproducing high energy density and large deformation with fast response time. The recent research emphasizes that tunable material properties eventually triggered the improved actuation performance. The exploration of compliant electrodes fabricated by the conventional and state-of-the-art lithographic methods was also crucial to improve actuation performance for the soft robotic applications. This review summarizes the commonly used DEs and dielectric fillers, their performances and challenges, and outlines the research progress (experimental and theoretical) in the field of actuators. Finally, a brief introduction to DEA-based soft robotics application is also presented.