Application Of Dielectric Elastomers Research Articles

Review of Dielectric elastomer based application for Soft robotics

Soft robotics is a growing field that is getting more and more attention. Unlike traditional rigid robots, soft robots have a simpler structure and control logic, a simple electric voltage change can activate the whole control system, with the capability of carrying out more complex tasks at the same time. Dielectric elastomer is thought to be a fundamental technology advancing the development of soft robots, with the advantages of fast response, great stretch capacity as well as resilience, less weight and higher energy density. Dielectric elastomer technology has many practical applications, such as grippers, robots on ground, swimming robots, artificial body tissues and so-called artificial muscles. In this paper, we mainly introduce the state-of-art application of Dielectric elastomer in the soft robotics field and also discuss the challenges that the DE-based soft robotics are encountering.

Arbitrarily Patterned Active Wrinkles in Highly Stretched Substrate-Free Dielectric Elastic Membrane

Abstract Dynamic wrinkle patterns provide an effective approach for on-demand tuning of membrane optical and mechanical properties to realize a smart membrane. Related applications depend on forming and controlling of a sophisticated wrinkling region. Herein, by using strip-structured electrode couples, we enable regular and ordered wrinkling patterns in an arbitrarily shaped region in a pre-stretched substrate-free dielectric elastic membrane. By considering the electromechanical coupling in a substrate-free hyperelastic membrane, the winkling condition and wavelength are predicated theoretically. Supported by the theoretical results, a series of experimental and numerical demonstrations are realized. The method proposed in this work provides a general framework for forming controllable highly ordered wrinkling patterns in a complex/large area of a substrate-free membrane, which could provide useful guidance for the application of dielectric elastomers in intelligent materials and structures.

A dielectric elastomer membrane integrated with protective passive layers under explicit and implicit prestretch

Dielectric elastomers (DEs) are a category of soft electro-active materials that can be used as sensors, actuators and generators. In order to provide protection, insulation layers are essential and thicker layers can lead to stronger protecion. However, the presence of the additional layers can certainly constrain the deformation of DEs. Thus a balance between protection and performance is needed. Prestretch is widely used for the enhancement of actuation performance. Thus the DE membrane integrated with protective passive layers is studied here, focusing on the effect of the coexistence of the prestretch and passive layers. We identify two approaches of prestretches, where the DE membrane and protective passive layers can be explicitly prestretched by external loads, or the DE membrane can be implicitly prestretched by solely protective passive layers. For the latter approach, it does not require additional components such as rigid clamps or dead weights. We then establish a coupled model for the DE membrane and passive layers. The effects of the prestretches and passive layers on the electromechanical behavior and voltage-induced deformation of the DE membrane are then revealed numerically. Furthermore, we theoretically study the detailed effects of specific mechanical properties of passive layers such as the thickness and shear modulus, which are useful for the design of the system. This theoretical research thus sheds insights for the design of dielectric elastomer applications where both safety and performance are required.

Influence of stretch and temperature on the energy density of dielectric elastomer generators

Application of dielectric elastomers (DE) has remarkably increased in mechatronics because they are suitable candidates for energy harvesting due to their low cost, light weight, and high energy density. The dielectric elastomer generators (DEGs) exhibit high performance regardless of the applications scale. However, functioning as a generator, a DE may lose its efficiency due to several failure modes including material rupture, loss of tension (LT), electrical breakdown (EB), and electromechanical instability (EMI). The failure modes confine the area of allowable states for generation process. Dielectric constant and dielectric strength of such elastomers depend on the amount of applied deformation and also working temperature, which are often ignored in theoretical simulations. In this paper, variations of the above-mentioned parameters are considered in mechanical and electrical modellings to investigate their effects on energy density and efficiency of generators. Obtained results show that, ignoring the variations of material dielectric constant and dielectric strength leads to overestimation of the specific energy. Furthermore, it is shown that, for an acrylic-based generator, the specific energy sharply decreases with temperature rise.

Post Curing as an Effective Means of Ensuring the Long-term Reliability of PDMS Thin Films for Dielectric Elastomer Applications

ABSTRACTPost curing can be used to facilitate volatile removal and thus produce polydimethylsiloxane (PDMS) films with stable elastic and electrical properties over time. In this study, the effect of post curing was investigated for commercial silicone elastomer thin films as a means of improving long-term elastomer film reliability. The Young’s moduli and electrical breakdown strengths of commercial (silica-reinforced) PDMS elastomer films, with and without additional 35 parts per hundred rubber titanium dioxide (TiO2), were investigated after high-temperature (200°C) post curing for various time spans. The elastomers were found to contain less than 2% of volatiles (significantly higher for TiO2-filled samples), but nevertheless a strong effect from post curing was observed. The young’s moduli as well as the strain-dependent behavior were found to change significantly upon post curing treatment, where Young’s moduli at 5% strain increase with post curing. Furthermore, the determined dielectric breakdown parameters from Weibull analyses showed that greater electrical stability and reliability could be achieved by post curing the PDMS films before usage, and this method therefore paves a way toward more reliable dielectric elastomers.