scholarly journals Enhancing dynamic actuation performance of dielectric elastomer actuators by tuning viscoelastic effects with polar crosslinking

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Matthew Wei Ming Tan ◽  
Gurunathan Thangavel ◽  
Pooi See Lee
Keyword(s):  
Fast Response ◽  
Dielectric Elastomer ◽  
Buckling Mode ◽  
Polyethylene Glycol Diacrylate ◽  
Glycol Diacrylate ◽  
Dielectric Elastomer Actuators ◽  
Polyurethane Acrylate ◽  
Out Of Plane ◽  
Viscoelastic Effects ◽  
Chemical Crosslinks

Abstract Dielectric elastomer actuators (DEAs) have shown great potential in the field of robotics, energy harvesting, or haptics for wearables. However, existing DEA materials typically require prestretching and exhibit time-dependent deformations due to their inherent viscoelastic properties. In this work, we address these issues by designing and synthesizing a polyurethane acrylate (PUA) DEA copolymerized with a polar crosslinker, polyethylene glycol diacrylate (PEGDA), to reduce viscoelastic effects through chemical crosslinking. We realized a buckling-mode actuator that displays out-of-plane deformations triggered by an electric field without the need for prestretching. Copolymerization with PEGDA showed improved dynamic response actuation performances compared to pristine PUA, wherein the former reached 90% of its maximum actuation in <1 s. In addition, precise and stable actuation was achieved, reducing viscoelastic drifts to a negligible amount. Despite the higher elastic modulus of the DEA incurred by the chemical crosslinks, the polar groups present in the PEGDA comonomer effectively increased the dielectric constant. As such, a higher area strain was achieved in comparison to that exhibited by low viscoelastic elastomers such as silicone. By eliminating the need for prestretching, rigid components can be avoided, thereby enabling greater prospects for the integration of fast response and stable DEAs into soft bodies.

scholarly journals Soft Robotic Gripper Based on Multi-Layers of Dielectric Elastomer Actuators

2021 ◽  
Vol 33 (4) ◽  
pp. 968-974
Author(s):  
Witchuda Thongking ◽  
Ardi Wiranata ◽  
Ayato Minaminosono ◽  
Zebing Mao ◽  
Shingo Maeda ◽  
...  
Keyword(s):  
Response Time ◽  
Low Cost ◽  
Fast Response ◽  
Dielectric Elastomer ◽  
Heel Strike ◽  
Soft Robotics ◽  
Artificial Muscles ◽  
Light Weight ◽  
Dielectric Elastomer Actuators ◽  
The Relationship

Dielectric elastomer actuators (DEAs) are a promising technology for soft robotics. The use of DEAs has many advantages, including light weight, resilience, and fast response for its applications, such as grippers, artificial muscles, and heel strike generators. Grippers are commonly used as grasping devices. In this study, we focus on DEA applications and propose a technology to expand the applicability of a soft gripper. The advantages of gripper-based DEAs include light weight, fast response, and low cost. We fabricated soft grippers using multiple DEA layers. The grippers successfully held or gripped an object, and we investigated the response time of the grippers and their angle characteristics. We studied the relationship between the number of DEA layers and the performance of our grippers. Our experimental results show that the multi-layered DEAs have the potential to be strong grippers.

scholarly journals Linear-Quadratic Regulator for Control of Multi-Wall Carbon Nanotube/Polydimethylsiloxane Based Conical Dielectric Elastomer Actuators

Actuators ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 18
Author(s):  
Titus Mulembo ◽  
Waweru Njeri ◽  
Gakuji Nagai ◽  
Hirohisa Tamagawa ◽  
Keishi Naito ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Rise Time ◽  
Electromechanical Coupling ◽  
Linear Quadratic Regulator ◽  
Fast Response ◽  
Dielectric Elastomer ◽  
Soft Robotics ◽  
Artificial Muscles ◽  
Linear Quadratic ◽  
Dielectric Elastomer Actuators

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.

scholarly journals A Detailed Solution Framework for the Out-of-Plane Displacement of Circular Dielectric Elastomer Actuators

2021 ◽  
Author(s):  
Hector Medina ◽  
Carson Farmer ◽  
Daniel Korn
Keyword(s):  
Numerical Solution ◽  
Theoretical Work ◽  
Dielectric Elastomer ◽  
Differential Algebraic Equations ◽  
Algebraic Equations ◽  
Dielectric Elastomer Actuators ◽  
Rigid Frame ◽  
Out Of Plane ◽  
Plane Displacement ◽  
Range Of Values

The out-of-plane displacement (OPD) of a circular dielectric elastomer actuator (DEA) membrane has been explored in recent years for a variety of important applications. Circular DEAs consist of an elastomer membrane that is prestretched to a rigid frame and coated with compliant electrodes. Such a simple configuration has found many interesting applications such as in, pumps, pulse tracking, hopping search and rescue robots, dielectric elastomer (DE) generators for renewable energy harvesting, linear actuators, and many others. Here, we present an easy-to-follow implementation of the OPD equations for circular DEAs via a detailed numerical solution using the shooting method (SM) on a system of differential algebraic equations (DAE), based on previous theoretical work. The SM numerical solution to the system of DAEs is applied to a practical range of values based on the reported literature. Analysis of the results and comparison against other studies are provided. The current work provides a go-to framework for implementation in further research and development.

scholarly journals Cell Nanomechanics Based on Dielectric Elastomer Actuator Device

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhichao Li ◽  
Chao Gao ◽  
Sisi Fan ◽  
Jiang Zou ◽  
Guoying Gu ◽  
...  
Keyword(s):  
Fast Response ◽  
Dielectric Elastomer ◽  
Dynamic Imaging ◽  
Time Dynamic ◽  
Interdisciplinary Field ◽  
Dielectric Elastomer Actuators ◽  
Potential Applications ◽  
Research Prospect ◽  
Extracellular Microenvironment ◽  
Cellular Mechanobiology

Abstract As a frontier of biology, mechanobiology plays an important role in tissue and biomedical engineering. It is a common sense that mechanical cues under extracellular microenvironment affect a lot in regulating the behaviors of cells such as proliferation and gene expression, etc. In such an interdisciplinary field, engineering methods like the pneumatic and motor-driven devices have been employed for years. Nevertheless, such techniques usually rely on complex structures, which cost much but not so easy to control. Dielectric elastomer actuators (DEAs) are well known as a kind of soft actuation technology, and their research prospect in biomechanical field is gradually concerned due to their properties just like large deformation (> 100%) and fast response (< 1 ms). In addition, DEAs are usually optically transparent and can be fabricated into small volume, which make them easy to cooperate with regular microscope to realize real-time dynamic imaging of cells. This paper first reviews the basic components, principle, and evaluation of DEAs and then overview some corresponding applications of DEAs for cellular mechanobiology research. We also provide a comparison between DEA-based bioreactors and current custom-built devices and share some opinions about their potential applications in the future according to widely reported results via other methods.

Modelling and Experimental Validation of Buckling Dielectric Elastomer Actuators

2011 ◽  
Author(s):  
Rocco Vertechy ◽  
Antonio Frisoli ◽  
Massimo Bergamasco ◽  
Federico Carpi ◽  
Gabriele Frediani ◽  
...  
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Experimental Validation ◽  
Element Model ◽  
Mechanical Analysis ◽  
Dielectric Elastomer ◽  
Elastic Instability ◽  
Dielectric Elastomer Actuators ◽  
Out Of Plane ◽  
Rubbery Material

Buckling dielectric elastomer actuators are special type of electro-mechanical transducers that exploit electro-elastic instability phenomena to generate large out-of-plane axial-symmetric deformations of circular membranes made of non-conductive rubbery material. In this paper a simplified explicit analytical model and a monolithic finite element model are described for the coupled electro-mechanical analysis and simulation of buckling dielectric elastomer membranes which undergo large electrically induced displacements. Experimental data are also reported which validate the developed models.

scholarly journals Mechanical behavior of a circular dielectric elastomer membrane under out-of-plane deformation

2020 ◽  
Vol 37 ◽  
pp. 184-191
Author(s):  
J W Zhang ◽  
J W Chen ◽  
Z Q Ren
Keyword(s):  
Mechanical Behavior ◽  
System Analysis ◽  
Plane Deformation ◽  
Dielectric Elastomer ◽  
Electrical Parameters ◽  
Dielectric Elastomer Actuators ◽  
Out Of Plane ◽  
Gent Model ◽  
Dielectric Elastomer Membrane ◽  
Theoretical Results

Abstract The mechanical behavior of a circular dielectric elastomer membrane (DEM) under the contact of a rigid ball is studied in this paper. The out-of-plane deformation of the DEM is unfolded to an equivalent in-plane deformation, and the mechanical behavior is further studied through the Helmholtz free energy theory and the Gent model. The theoretical results obtained from the proposed analysis approach are validated through the out-of-plane deformation experiments, and the influence of the DEM's thickness on the mechanical behavior is revealed and explained. Furthermore, the influences of some key dimensional, dynamical and electrical parameters on the DEM's mechanical behavior are investigated and discussed. The research results are helpful for the system analysis of dielectric elastomer actuators and dielectric elastomer generators with out-of-plane deformations.

scholarly journals Elucidating the Molecular Mechanisms for the Interaction of Water with Polyethylene Glycol-Based Hydrogels: Influence of Ionic Strength and Gel Network Structure

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 845
Author(s):  
Xin Yang ◽  
Bronwin Dargaville ◽  
Dietmar Hutmacher
Keyword(s):  
Polyethylene Glycol ◽  
Ionic Strength ◽  
Molecular Mechanisms ◽  
Repeat Unit ◽  
Bound Water ◽  
Weight Fraction ◽  
Swelling Ratio ◽  
Polyethylene Glycol Diacrylate ◽  
Glycol Diacrylate ◽  
Hydrogel System

The interaction of water within synthetic and natural hydrogel systems is of fundamental importance in biomaterial science. A systematic study is presented on the swelling behavior and states of water for a polyethylene glycol-diacrylate (PEGDA)-based model neutral hydrogel system that goes beyond previous studies reported in the literature. Hydrogels with different network structures are crosslinked and swollen in different combinations of water and phosphate-buffered saline (PBS). Network variables, polyethylene glycol (PEG) molecular weight (MW), and weight fraction are positively correlated with swelling ratio, while “non-freezable bound water” content decreases with PEG MW. The presence of ions has the greatest influence on equilibrium water and “freezable” and “non-freezable” water, with all hydrogel formulations showing a decreased swelling ratio and increased bound water as ionic strength increases. Similarly, the number of “non-freezable bound water” molecules, calculated from DSC data, is greatest—up to six molecules per PEG repeat unit—for gels swollen in PBS. Fundamentally, the balance of osmotic pressure and non-covalent bonding is a major factor within the molecular structure of the hydrogel system. The proposed model explains the dynamic interaction of water within hydrogels in an osmotic environment. This study will point toward a better understanding of the molecular nature of the water interface in hydrogels.

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