Abstract
We introduce a dielectric elastomer actuator (DEA) composed of liquid-phase Gallium-Indium (GaIn) alloy electrodes embedded between layers of poly(dimethylsiloxane) (PDMS) and examine its mechanics using a specialized elastic shell theory. Residual stresses in the dielectric and sealing layers of PDMS cause the DEA to deform into a saddle-like geometry (Gaussian curvature K<0). Applying voltage Φ to the liquid metal electrodes induces electrostatic pressure (Maxwell stress) on the dielectric and relieves some of the residual stress. This reduces the longitudinal bending curvature and corresponding angle of deflection ϑ. Treating the elastomer as an incompressible, isotropic, NeoHookean solid, we develop a theory based on the principle of minimum potential energy to predict the principal curvatures as a function of Φ. Based on this theory, we predict a dependency of ϑ on Φ that is in strong agreement with experimental measurements performed on a GaIn-PDMS composite. By accurately modeling electromechanical coupling in a soft-matter DEA, this theory can inform improvements in design and fabrication.
Highlights
Dielectric elastomer actuators (DEAs) represent a promising alternative to conventional actuator technologies for powering soft bio-inspired robots, assistive wearable technologies, and other systems that depend on mechanical “impedance matching” with soft biological tissue
We introduce a dielectric elastomer actuator (DEA) composed of liquid-phase Gallium-Indium (GaIn) alloy electrodes embedded between layers of poly(dimethylsiloxane) (PDMS) and examine its mechanics using a specialized elastic shell theory
We introduce a DEA composed of liquid-phase Gallium-Indium (GaIn) alloy electrodes embedded between layers of poly(dimethylsiloxane) (PDMS)
Summary
Dielectric elastomer actuators (DEAs) represent a promising alternative to conventional actuator technologies for powering soft bio-inspired robots, assistive wearable technologies, and other systems that depend on mechanical “impedance matching” with soft biological tissue. In contrast to electrical motors and hydraulics, DEAs can be made entirely out of soft elastic materials and fluids and remain functional under extreme bending and stretching. They operate with very little electrical power and can exhibit as much as 90% efficiency of electrical energy input to mechanical work output. While there have been significant improvements since early studies in the late 1990s, progress in DEA performance and robotics implementation continues to depend on advancements in materials selection, design, and predictive theoretical modeling of the underlying elasticity and electromechanical coupling. Electronic mail: DEAs are composed of a soft insulating elastomer film coated with conductive fluid or rubber electrodes. DEA designs include diaphragms, bimorphs, rolls, and reinforced planar stacks and exhibit a variety of motions, load capacities, and electromechanical coupling
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