Dielectric elastomer actuators are soft electro-mechanical transducers with possible uses in robotic, orthopaedic and
automotive applications. The active material must be soft and have a high ability to store electrical energy. Hence, three
properties of the elastic medium in a dielectric elastomer actuator affect the actuation properties directly: dielectric
constant, electric breakdown strength, and mechanical stiffness. The dielectric constant of a given elastomer can be
improved by mixing it with other components with a higher dielectric constant, which can be classified as insulating or
conducting. In this paper, an overview of all approaches proposed so far for dielectric constant improvement in these soft
materials will be provided.
Insulating particles such as TiO2 nanoparticles can raise the dielectric constant, but may also lead to stiffening of the
composite, such that the overall actuation is lowered. It is shown here how a chemical coating of the TiO2 nanoparticles
leads to verifiable improvements. Conducting material can also lead to improvements, as has been shown in several
cases. Simple percolation, relying on the random distribution of conducting nanoparticles, commonly leads to drastic
lowering of the breakdown strength. On the other hand, conducting polymer can also be employed, as has been
demonstrated. We show here how an approach based on a specific chemical reaction between the conducting polymer
and the elastomer network molecules solves the problem of premature breakdown which is otherwise typically found.