Special Issue "Dielectric Elastomer Actuators (DEAs)"

A special issue of Actuators (ISSN 2076-0825).

Deadline for manuscript submissions: closed (30 September 2020).

Special Issue Editor

Prof. Dr. Jun Shintake
E-Mail Website
Guest Editor
Graduate School of Informatics and Engineering, Department of Mechanical and Intelligent Systems Engineering, The University of Electro-Communications, Tokyo 182-8585, Japan
Interests: dielectric elastomer actuators; soft robotics; soft actuators; soft sensors

Special Issue Information

Dear Colleagues,

We are pleased to invite you to submit your paper(s) to our Special Issue on “Dielectric elastomer actuators (DEAs)” in Actuators (ISSN 2076-0825). Both original research and review articles are welcome. Deadline: 30 September 2020.

Along with recent advances in materials sciences, stretchable electronics, and mechatronics, the research and development of dielectric elastomer actuators (DEAs) is rapidly increasing. The reasons lie in their multifunctionality, scalability, and performance characteristics resembling skeletal muscles, making them a promising solution for the creation of next-generation machines and devices driven by soft intelligent materials. DEAs are a type of electroactive polymers made of compliant elastomers and are able to generate large actuation strokes, exhibit a fast response, and have theoretically high electro-mechanical efficiency compared to other soft actuator technologies. Applications of DEAs cover a wide range of fields such as soft robotics, optics, and medical and biological engineering, to name a few, which are expected to expand substantially in the years and decades ahead. To highlight the current status and perspectives, this Special Issue invites contributions from all aspects of DEAs, including but not limited to:

  • Novel robots, actuator configurations, and other mechatronic devices;
  • Switches, generators, and other transducers;
  • Theory and modeling;
  • Design, fabrication, and control;
  • Applications in research, industry, and education.

Prof. Dr. Jun Shintake
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Actuators is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Dielectric elastomer actuators (DEAs)
  • Electroactive polymers (EAPs)
  • Smart materials
  • Artificial muscles
  • Soft robotics
  • Soft transducers
  • Haptics
  • Electroadhesion

Published Papers (5 papers)

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Research

Article
A Simple Dynamic Characterization Method for Thin Stacked Dielectric Elastomer Actuators by Suspending a Weight in Air and Electrical Excitation
Actuators 2021, 10(3), 40; https://doi.org/10.3390/act10030040 - 24 Feb 2021
Viewed by 591
Abstract
This paper proposes a simple but effective method for characterizing dielectric elastomer actuators (DEAs), especially for thin stacked DEAs, which are promising for haptic devices but which measure the dynamic elastic modulus with great difficulty. The difficulty of the measurement of such a [...] Read more.
This paper proposes a simple but effective method for characterizing dielectric elastomer actuators (DEAs), especially for thin stacked DEAs, which are promising for haptic devices but which measure the dynamic elastic modulus with great difficulty. The difficulty of the measurement of such a thin stacked DEA arises from the friction and local deformation of the surface between the DEA and a contact, as shown in this paper. In the proposed method, a DEA is vertically suspended and a weight is attached to it. The proposed method requires no contact with the surface of a DEA and uses only a weighting mass. Experimental results demonstrated the proposed method can estimate almost essential constants, such as the dynamic elastic modulus (Young’s modulus and damping time constant), the electrical constants (permittivity and resistivity), and the coefficient of electromechanical coupling, through the forced vibration induced by voltage actuation. Full article
(This article belongs to the Special Issue Dielectric Elastomer Actuators (DEAs))
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Article
Effects of Thinner Compliant Electrodes on Self-Clearability of Dielectric Elastomer Actuators
Actuators 2020, 9(4), 121; https://doi.org/10.3390/act9040121 - 26 Nov 2020
Viewed by 636
Abstract
A metalized plastic capacitor stands a higher chance to clear faults when embodied with thinner electrodes. However, it is not clear whether the same thickness effect applies to carbon-based compliant electrodes in clearing the defects in dielectric elastomer actuators (DEA). This experimental study [...] Read more.
A metalized plastic capacitor stands a higher chance to clear faults when embodied with thinner electrodes. However, it is not clear whether the same thickness effect applies to carbon-based compliant electrodes in clearing the defects in dielectric elastomer actuators (DEA). This experimental study showed that charcoal-powder compliant electrodes act like fuses and current limiters to successfully clear the defects of an acrylic dielectric elastomer actuator, provided a very thin electrode coating. For example, DEAs with 3 μm thick (average) charcoal-powder electrodes fast cleared faults and sustained high breakdown strength (300 to 400 MV/m), but the ones with thicker charcoal-powder electrodes (30 μm thick on average) succumbed to persisting breakdowns in a weaker electric field (200 to 300 MV/m). Thermo-gravitational analysis and differential scanning calorimetry showed that dielectric elastomer (3M VHB F9473PC) started to ignite at 350 C, and charcoal powders (Mungyo charcoal pastel MP-12CP) started burning above 450 C. This confirmed that flash ignition and its damping of charcoal powder is possible only with a very thin electrode coating relative to acrylic elastomer substrate thickness. Too thick of a charcoal-powder coating could lead to the spread of burning beyond the initial flash point, and incomplete burning that punctures the dielectric layer but shorts across opposite electrodes. With this insight, one can design self-clearable electrodes to improve the dielectric strength of dielectric elastomer actuators. Full article
(This article belongs to the Special Issue Dielectric Elastomer Actuators (DEAs))
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Communication
Energy Harvesting of Ionic Polymer-Metal Composites Based on Microcellular Foamed Nafion in Aqueous Environment
Actuators 2020, 9(3), 71; https://doi.org/10.3390/act9030071 - 17 Aug 2020
Cited by 1 | Viewed by 1195
Abstract
The purpose of this study was to determine how to improve the energy-harvesting properties of polymer electrolyte membranes by varying their porosity. We achieved this by applying microcellular foaming process (MCP) to Nafion-based ionic polymer–metal composites (IPMCs). We manufactured an IPMC by forming [...] Read more.
The purpose of this study was to determine how to improve the energy-harvesting properties of polymer electrolyte membranes by varying their porosity. We achieved this by applying microcellular foaming process (MCP) to Nafion-based ionic polymer–metal composites (IPMCs). We manufactured an IPMC by forming a Pt electrode through an electroless plating method on the Nafion film, to which porosity was imparted by varying the foaming ratio and inducing deformation by vibrating the specimen using a prototype device that we developed ourselves. We attempted to harvest energy via fluid flow that occurred owing to displacement movement. When the Nafion film was foamed at a temperature of 140 °C or higher, it was observed that cells with size of approximately 1 µm or more were formed, and when the saturation temperature was lowered, a denser and larger number of cells were formed. Moreover, the cells formed on the electrolyte membrane allowed the retention of more water. Water retention generated charges contributed to the operational stability of IPMC. This was attributed to the difference in the amount of charge generated by changing only the internal morphology of the electrolyte membrane, without changing the substrate or the electrode material. Full article
(This article belongs to the Special Issue Dielectric Elastomer Actuators (DEAs))
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Article
Styrenic-Rubber Dielectric Elastomer Actuator with Inherent Stiffness Compensation
Actuators 2020, 9(2), 44; https://doi.org/10.3390/act9020044 - 05 Jun 2020
Cited by 1 | Viewed by 1683
Abstract
Up to date, Dielectric Elastomer Actuators (DEA) have been mostly based on either silicone or acrylic elastomers, whereas the potential of DEAs based on inexpensive, wide-spread natural and synthetic rubbers has been scarcely investigated. In this paper, a DEA based on a styrene-based [...] Read more.
Up to date, Dielectric Elastomer Actuators (DEA) have been mostly based on either silicone or acrylic elastomers, whereas the potential of DEAs based on inexpensive, wide-spread natural and synthetic rubbers has been scarcely investigated. In this paper, a DEA based on a styrene-based rubber is demonstrated for the first time. Using a Lozenge-Shaped DEA (LS-DEA) layout and following a design procedure previously proposed by the authors, we develop prototypes featuring nearly-zero mechanical stiffness, in spite of the large elastic modulus of styrenic rubber. Stiffness compensation is achieved by simply taking advantage of a biaxial pre-stretching of the rubber DE membrane, with no need for additional stiffness cancellation mechanical elements. In the paper, we present a characterization of the styrene rubber-based LS-DEA in different loading conditions (namely, isopotential, isometric, and isotonic), and we prove that actuation strokes of at least 18% the actuator side length can be achieved, thanks to the proposed stiffness-compensated design. Full article
(This article belongs to the Special Issue Dielectric Elastomer Actuators (DEAs))
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Article
Linear-Quadratic Regulator for Control of Multi-Wall Carbon Nanotube/Polydimethylsiloxane Based Conical Dielectric Elastomer Actuators
Actuators 2020, 9(1), 18; https://doi.org/10.3390/act9010018 - 13 Mar 2020
Viewed by 2168
Abstract
Conventional rigid actuators, such as DC servo motors, face challenges in utilizing them in artificial muscles and soft robotics. Dielectric elastomer actuators (DEAs) overcome all these limitations, as they exhibit complex and fast motions, quietness, lightness, and softness. Recently, there has been much [...] Read more.
Conventional rigid actuators, such as DC servo motors, face challenges in utilizing them in artificial muscles and soft robotics. Dielectric elastomer actuators (DEAs) overcome all these limitations, as they exhibit complex and fast motions, quietness, lightness, and softness. Recently, there has been much focus on studies of the DEAs material’s non-linearity, the non-linear electromechanical coupling, and viscoelastic behavior of VHB and silicone-based conical DEAs having compliant electrodes that are based on graphite powder and carbon grease. However, the mitigation of overshoot that arises from fast response conical DEAs made with solid electrodes has not received much research focus. In this paper, we fabricated a conical configuration of multi-walled carbon nanotube/polydimethylsiloxane (MWCNT/PDMS) based DEAs with a rise time of 10 ms, and 50% peak overshoot. We developed a full feedback state-based linear-quadratic regulator (LQR) having Luenberger observer to mitigate the DEAs overshoot in both the voltage ON and OFF instances. The cone DEA’s model was identified and a stable and well-fitting transfer function with a fit of 94% was obtained. Optimal parameters Q = 70,000, R = 0.1, and Q = 7000, R = 0.01 resulted in the DEA response having a rise time value of 20 ms with zero overshoot, in both simulations and experiments. The LQR approach can be useful for the control of fast response DEAs and this would expand the potential use of the DEAs as artificial muscles in soft robotics. Full article
(This article belongs to the Special Issue Dielectric Elastomer Actuators (DEAs))
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