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Animals make use of soft tissues and muscles to produce fluidic motion with superior deformability and adaptability. Soft robotics focuses on mimicking these natural soft systems to produce similar motion. Common approaches to achieve actuation in soft robotics are pneumatics, fluidics, shape memory materials, magnetic fields, chemical reactions and electroactive polymers (EAPs). EAPs are particularly interesting due to their high efficiencies, lightweight design and superior structural compliance. Dielectric elastomer actuators (DEAs), an EAP, can produce large strains, low cost and complexity of fabrication. Performance of a DEA depends on intrinsic material properties like relative permittivity and Young’s modulus. Conventional approaches to manipulate either of these material properties have made use of solid fillers, chemical additives and modifications of polymer backbone, and are generally accompanied with undesirable effects on other properties. In the present work, we demonstrate the fabrication of self-contained liquid filler-polymer composite, with synergetic effects on electrical and mechanical properties of the resulting matrix. A high-k, non-reactive liquid filler was hand mixed with PDMS (polydimethylsiloxane). These composites show an increase of 2 times in the relative permittivity (dielectric constant) and softening of the matrix (more than 50 times decrease in the Young’s modulus), compared to the pristine polymer. The composites can be actuated without pre-stretch with visibly detectable deformations and the figure of merit for electro-mechanical performance was calculated at an impressive value of 94. These ultra-soft composites can be used for applications such as soft robotics, optoelectronics and wearable electronics.
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