A soft polymer actuator has been constructed based on the volume change of a conducting polymer. The linear expansion (12 % at a load of 0.5 MPa) is the highest yet reported for a centimeter‐scale conducting polymer actuator. This is achieved by controlling the structure on several length scales: Choice of molecular structure, synthesis from a structured medium, and forming the polymer actuator on a compliant, microstructured gold electrode.

Progress in research and development in the field of electro-active polymers has enabled prototype fabrication, which demonstrates the future potential and versatility offered by this technology. These prototypes can be qualified as laboratory demonstrators. A new design of dielectric elastomer linear actuators is presented here. These actuators have the unique properties of being self-supporting and core-free. They are capable of large push forces and are fabricated based on large-scale industrial manufacturing processes. Actuators can be easily scaled to fit specific application needs. Actuator design and construction principles, as well as modelling are presented and discussed for push InLastor  actuators. The actuators exhibit modest strokes and high actuation forces. Current design considerations indicate that the achievable force output is reduced by about 40% due to the passive ends of the actuator. Dielectric electro-active polymer DEAP film manufacturing challenges contribute to reducing the achievable breakdown strength to 35 V µm −1 and limit the strain to modest figures. It is shown that push InLastor actuators can be operated at field strength levels above 45 V µm −1 , and exhibit larger strokes and forces in good agreement with the model. At these elevated electric field levels, risks of catastrophic breakdown increase, resulting in reduced actuator lifetime. A major milestone in the manufacturing of actuators based on the DEAP technology has been achieved by Danfoss PolyPower. Large-scale manufacturing of robust and reliable push tubular actuators is possible. Roll-to-roll manufacturing processes make it possible to manufacture these powerful actuators, based on PolyPower compliant electrode design.

In this paper we investigate the performance of liquid silicone rubbers (LSRs) as dielectric elastomer transducers. Commonly used silicones in this application include room-temperature vulcanisable (RTV) silicone elastomers and composites thereof. Pure LSRs and their composites with commercially available fillers (an anatase TiO 2 , a core-shell TiO 2 -SiO 2 and a CaCu 3 Ti 4 O 12 filler) are evaluated with respect to dielectric permittivity, elasticity (Young's modulus) and electrical breakdown strength. Film formation properties are also evaluated. The best-performing formulations are those with anatase TiO 2 nanoparticles, where the highest relative dielectric permittivity of 5.6 is obtained, and with STX801, a core-shell morphology TiO 2 -SiO 2 filler from Evonik, where the highest breakdown strength of 173 V μm −1 is obtained.

No abstract

In practice, the electrical breakdown strength of dielectric electroactive polymers (DEAPs) determines the upper limit for transduction. During DEAP actuation, the thickness of the elastomer decreases, and thus the electrical field increases and the breakdown process is determined by a coupled electro-mechanical failure mechanism. A thorough understanding of the mechanisms behind the electro-mechanical breakdown process is required for developing reliable transducers. In this study, two experimental configurations were used to determine the stretch dependence of the electrical breakdown strength of polydimethylsiloxane (PDMS) elastomers. Breakdown strength was determined for samples with and without volume conservation and was found to depend strongly on the stretch ratio and the thickness of the samples. PDMS elastomers are shown to increase breakdown strength by a factor of ∼3 when sample thickness decreases from 120 to 30 μm, while the biaxial pre-stretching (λ = 2) of samples leads similarly to an increase in breakdown strength by a factor of ∼2.5.