Abstract
Dielectric elastomer actuators (DEAs) are an emerging type of soft actuation technology. As a fundamental unit of a DEA, the characteristics of compliant electrodes play a crucial role in the actuation performances of DEAs. Generally, the compliant electrodes can be categorized into uncured and cured types, of which the cured one commonly involves mixing conductive particles into an elastomeric matrix before curing, thus demonstrating a better long-term performance. Along with the increasing proportion of conductive particles, the electrical conductivity increases at the cost of a stiffer electrode and lower elongation at break ratio. For different DEA applications, it can be more desirable to minimize the electrode stiffness or to maximize its conductivity. In examination of the papers published in recent years, few works have characterized the effects of elastomeric electrodes on the outputs of DEAs, or of their optimizations under different application scenarios. In this work, we propose an experimental framework to characterize the performances of elastomeric electrodes with different formulas based on the two key parameters of stiffness and conductivity. An optimizing method is developed and verified by two different application cases (e.g., quasi-static and dynamic). The findings and the methods developed in this work can offer potential approaches for developing high-performance DEAs.
Highlights
Dielectric elastomer actuators (DEAs), an emerging type of soft actuation technology, demonstrate advantages over conventional actuators in terms of large actuation strain, high energy density, fast responses, and low cost [1,2]
A fundamental DEA consists of a piece of dielectric elastomer (DE)
Despite the fact that acrylic DE has a high quasi-static actuation strain due to the low elastic modulus and high dielectric constant, its high viscoelasticity leads to a slow response speed and a reduced dynamic output
Summary
Dielectric elastomer actuators (DEAs), an emerging type of soft actuation technology, demonstrate advantages over conventional actuators in terms of large actuation strain, high energy density, fast responses, and low cost [1,2]. The most widely adopted DE materials include acrylic (e.g., 3M VHB 4910 [3,4] and silicone (e.g., Wacker ELASTOSIL 2030 [5,6], Wacker RT 625 [7]). Despite the fact that acrylic DE has a high quasi-static actuation strain due to the low elastic modulus and high dielectric constant, its high viscoelasticity leads to a slow response speed and a reduced dynamic output. Silicone elastomers show a significantly lower viscoelasticity, an improved dynamic output performance with a peak output power density (~600 W/kg) higher than natural muscles reported to date [8]. The promising applications of silicone-based DEAs have been widely demonstrated in the literature, including a soft pump [9,10], soft crawling robot [11], flapping wing micro-air-vehicles [12] and a versatile soft gripper [13]
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