Silicone dielectric elastomers optimized by crosslinking pattern – a simple approach to high-performance actuators

AbstractDielectric elastomer actuators (DEAs) with large electrically-actuated strain can build light-weight and flexible non-magnetic motors. However, dielectric elastomers commonly used in the field of soft actuation suffer from high stiffness, low strength, and high driving field, severely limiting the DEA’s actuating performance. Here we design a new polyacrylate dielectric elastomer with optimized crosslinking network by rationally employing the difunctional macromolecular crosslinking agent. The proposed elastomer simultaneously possesses desirable modulus (~0.073 MPa), high toughness (elongation ~2400%), low mechanical loss (tan δm = 0.21@1 Hz, 20 °C), and satisfactory dielectric properties ($${\varepsilon }_{{{{{{\rm{r}}}}}}}$$ ε r = 5.75, tan δe = 0.0019 @1 kHz), and accordingly, large actuation strain (118% @ 70 MV m−1), high energy density (0.24 MJ m−3 @ 70 MV m−1), and rapid response (bandwidth above 100 Hz). Compared with VHBTM 4910, the non-magnetic motor made of our elastomer presents 15 times higher rotation speed. These findings offer a strategy to fabricate high-performance dielectric elastomers for soft actuators.

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Hydrostatically Coupled Dielectric Elastomer Actuators: New Opportunities for Haptics

MRS Proceedings ◽

10.1557/opl.2011.668 ◽

2011 ◽

Vol 1312 ◽

Cited By ~ 2

Author(s):

Federico Carpi ◽

Gabriele Frediani ◽

Danilo De Rossi

Keyword(s):

High Performance ◽

New Technology ◽

Relative Displacement ◽

Dielectric Elastomer ◽

Tactile Feedback ◽

Haptic Interfaces ◽

Silicone Grease ◽

Performance Technology ◽

Hydrostatic Transmission ◽

Dielectric Elastomer Actuators

ABSTRACTDielectric elastomer actuators (DEAs) have been demonstrated to represent today a high-performance technology for electromechanical transducers based on electroactive polymers. As a means to improve versatility and safety of DEAs for several fields of application, so-called ‘hydrostatically coupled’ DEAs (HC-DEAs) have recently been described. HC-DEAs are based on an incompressible fluid that mechanically couples a DE-based active part to a passive part interfaced to the load, so as to enable hydrostatic transmission. This paper presents ongoing developments of bubble-like HC-DEAs and their promising potential application in the field of haptics. In particular, the first part of the paper describes a static and dynamic characterization of a prototype actuator made of two pre-stretched membranes (20 mm wide, 1.8 mm high, and 60 μm thick) of 3M VHB acrylic elastomer, coupled via silicone grease. The actuator exhibited a maximum stress of 1.3 kPa at 4.4 kV, a relative displacement of -80% at 4.4 kV, a -3dB bandwidth of 3 Hz, and a resonance frequency of 160 Hz. The second part of the paper presents possible applications of the tested actuator configuration for haptic interfaces. Two specific examples are considered. The first deals with a wearable tactile/haptic display used to provide users with tactile feedback during electronic navigation in virtual environments. The display consists of HC-DEAs arranged in contact with finger tips. As a second example of usage, an up-scaled prototype version of an 8-dots refreshable cell for dynamic Braille displays is shown. Each Braille pin consists of a miniature HC-DEA, with a diameter lower than 2 mm. Both types of applications clearly show the potential of the new technology and the prospective opportunities for haptics.

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ZnO as a cheap and effective filler for high breakdown strength elastomers

RSC Advances ◽

10.1039/c7ra09479e ◽

2017 ◽

Vol 7 (72) ◽

pp. 45784-45791 ◽

Cited By ~ 9

Author(s):

Liyun Yu ◽

Anne Ladegaard Skov

Keyword(s):

High Performance ◽

Breakdown Strength ◽

New Products ◽

Dielectric Elastomer ◽

Dielectric Elastomers ◽

High Demand

Cheap, high-performance dielectric elastomers are in high demand from industry concerning new products based on dielectric elastomer transducers.

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Inkjet 3D printing of UV and thermal cure silicone elastomers for dielectric elastomer actuators

Smart Materials and Structures ◽

10.1088/1361-665x/aa9695 ◽

2017 ◽

Vol 26 (12) ◽

pp. 125022 ◽

Cited By ~ 44

Author(s):

David McCoul ◽

Samuel Rosset ◽

Samuel Schlatter ◽

Herbert Shea

Keyword(s):

3D Printing ◽

Dielectric Elastomer ◽

Thermal Cure ◽

Silicone Elastomers ◽

Dielectric Elastomer Actuators

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Characterization of slide ring materials for dielectric elastomer actuators

Smart Materials and Structures ◽

10.1088/1361-665x/ac42e9 ◽

2021 ◽

Author(s):

Jun Shintake ◽

Koya Matsuno ◽

Kazumasa Baba ◽

Hiromitsu Takeuchi

Keyword(s):

Electric Fields ◽

High Performance ◽

Mechanical Performance ◽

Dielectric Strength ◽

Dielectric Elastomer ◽

Elongation At Break ◽

Dielectric Elastomer Actuators ◽

Elastomeric Materials ◽

Mechanical Performances

Abstract This paper investigates the characteristics of sliding ring materials (SRMs), which are promising elastomeric materials for dielectric elastomer actuators (DEAs). Two different types of SRMs with Young's modulus of 0.8 MPa and 3.3 MPa, respectively, are prepared, and their material and mechanical properties and electro-mechanical performances at electric fields of up to 30 V/um are characterized. For comparison, the same tests are also performed on several commercially available elastomers: Elastosil 2030, Ecoflex 00-30, CF19-2186, and VHB 4905. The results reveal that SRMs demonstrate negligible Mullins effect and hysteresis, while their dielectric strength (62.4‒112.4 V/µm) and viscoelasticity (tan⁡δ 0.07‒0.24 at 10 Hz) are comparable or even superior to those of other elastomers. In addition, elongation at break is found to be 163.8‒172.1%. SRMs exhibit excellent electro-mechanical performance; for instance, one of the two types has an actuation force 293.2 mN at 24.9 V/µm and a strain of 5.2% at 22.3 V/µm. These values are the largest or larger than most of the tested elastomers. The high performance of SRMs results from their dielectric constant, which ranges from 10.3‒13.4, leading to an electro-mechanical sensitivity of up to 15.3 MPa-1. These results illustrate SRMs as attractive material options for DEAs.

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Instability in Nonlinear Oscillation of Dielectric Elastomers

Journal of Applied Mechanics ◽

10.1115/1.4030075 ◽

2015 ◽

Vol 82 (6) ◽

Cited By ~ 13

Author(s):

Jian Zhu

Keyword(s):

Nonlinear Oscillation ◽

Electromechanical Coupling ◽

Haptic Feedback ◽

Dynamic Instability ◽

Dielectric Elastomer ◽

Dielectric Elastomers ◽

Critical Amplitude ◽

Dielectric Elastomer Actuators ◽

Coupling Dynamic ◽

Static Instability

A membrane of a dielectric elastomer oscillates when subject to AC voltage. Its oscillation is nonlinear due to large deformation and nonlinear electromechanical coupling. Dynamic instability in dielectric elastomers—the oscillation with an unbounded amplitude—is investigated in this paper. The critical amplitude of AC voltage for dynamic instability varies with the frequency of AC voltage and reaches a valley when the superharmonic, harmonic, or subharmonic resonance is excited. Prestretches can improve dielectric elastomer actuators' capabilities to resist dynamic instability. The critical deformation at the onset of dynamic instability can be much larger than that at the onset of static instability. Oscillation of dielectric elastomers can be used for applications, such as vibration shakers for haptic feedback, soft loudspeakers, soft motors, and soft pumps. We hope that the current analyses can improve the understanding of dynamic behavior of dielectric elastomers and enhance their stability and reliability.

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Characterization and Optimization of Elastomeric Electrodes for Dielectric Elastomer Artificial Muscles

Materials ◽

10.3390/ma13235542 ◽

2020 ◽

Vol 13 (23) ◽

pp. 5542

Author(s):

Guangqiang Ma ◽

Xiaojun Wu ◽

Lijin Chen ◽

Xin Tong ◽

Weiwei Zhao

Keyword(s):

High Performance ◽

Dielectric Elastomer ◽

Elastomeric Matrix ◽

Dielectric Elastomer Actuators ◽

Lower Elongation ◽

The Cost ◽

Long Term Performance ◽

Term Performance ◽

Conductive Particles ◽

Compliant Electrodes

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.

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Improved Materials for Dielectric Elastomer Actuators

Volume 1: Advanced Energy Systems; Advanced and Digital Manufacturing; Advanced Materials; Aerospace ◽

10.1115/esda2008-59193 ◽

2008 ◽

Author(s):

Dorina Opris ◽

Martin Molberg ◽

Christiane Lo¨we ◽

Frank Nu¨esch ◽

Christopher Plummer ◽

...

Keyword(s):

Mechanical Properties ◽

Dielectric Constant ◽

Electroactive Polymers ◽

Dielectric Elastomer ◽

Electromechanical Properties ◽

Silicone Elastomers ◽

Broad Application ◽

Dielectric Elastomer Actuators ◽

Electromechanical Transduction ◽

Doped Polyaniline

Dielectric elastomers are an emerging class of electroactive polymers for electromechanical transduction. A broad application of dielectric elastomer actuators (DEA) is limited by the high voltage necessary to drive such devices. The development of novel elastomers offering better intrinsic electromechanical properties is one way to solve the problem. Therefore we prepared composites from thermoplastic or thermoset silicone elastomers and organic fillers as phthalocyanines or doped polyaniline (PANI). We studied the mechanical properties of silicones, synthesized, modified and characterized phthalocyanines and doped PANI. The influence of humidity onto the dielectric properties of CuPc(COOH)8 and ZnPc(COOH)8 was analyzed in detail. First measurements of silicone/PANI blends results in a hundredfold increase for the dielectric constant and an electromechanically strain of 8.5%.

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