Dielectric Elastomer Energy Harvesting and its Application to Human Walking

2011 ◽  
Author(s):  
Heather Lai ◽  
Chin An Tan ◽  
Yong Xu
Keyword(s):  
Energy Harvesting ◽  
Knee Joint ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
High Energy ◽  
Dielectric Elastomer ◽  
Metabolic Energy ◽  
High Energy Density ◽  
Human Walking ◽  
Wide Range

Human walking requires sophisticated coordination of muscles, tendons, and ligaments working together to provide a constantly changing combination of force, stiffness and damping. In particular, the human knee joint acts as a variable damper, dissipating greater amounts of energy when the knee undergoes large rotational displacements during walking, running or hopping. Typically, this damping results from the dissipation, or loss, of metabolic energy. It has been proven to be possible however; to collect this otherwise wasted energy through the use of electromechanical transducers of several different types which convert mechanical energy to electrical energy. When properly controlled, this type of device not only provides desirable structural damping effects, but the energy generated can be stored for use in a wide range of applications. A novel approach to an energy harvesting knee joint damper is presented using a dielectric elastomer (DE) smart material based electromechanical transducer. Dielectric elastomers are extremely elastic materials with high electrical permittivity which operate based on electrostatic effects. By placing compliant electrodes on either side of a dielectric elastomer film, a specialized capacitor is created, which couples mechanical and electrical energy using induced electrostatic stresses. Dielectric elastomer energy harvesting devices not only have a high energy density, but the material properties are similar to that of human tissue, making it highly suitable for wearable applications. A theoretical framework for dielectric elastomer energy harvesting is presented along with a mapping of the active phases of the energy harvesting to the appropriate phases of the walking stride. Experimental results demonstrating the energy harvesting capability of a DE generator undergoing strains similar to those experienced during walking are provided for the purpose of verifying the theoretical results. The work presented here can be applied to devices for use in rehabilitation of patients with muscular dysfunction and transfemoral prosthesis as well as energy generation for able-bodied wearers.

scholarly journals Dielectric Elastomer Generator for Electromechanical Energy Conversion: A Mini Review

2021 ◽  
Vol 13 (17) ◽  
pp. 9881
Author(s):  
Kui Di ◽  
Kunwei Bao ◽  
Haojie Chen ◽  
Xinjun Xie ◽  
Jianbo Tan ◽  
...  
Keyword(s):  
Large Scale ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
Fast Response ◽  
High Energy ◽  
Dielectric Elastomer ◽  
Human Motion ◽  
High Energy Density ◽  
Small Scale ◽  
Electromechanical Energy Conversion

The dielectric elastomer generator (DEG) has attracted attention in converting mechanical energy into electrical energy, due to its high energy density, fast response, and light weight, which together make DEG a promising technology for electromechanical conversion. In this article, recent research papers on DEG are reviewed. First, we present the working principles, parameters, materials, and deformation modes of DEG. Then, we introduce DEG prototypes in the field of collecting mechanical energy, including small-scale applications for wind energy and human motion energy, and large-scale applications for wave energy. At the end of the review, we discuss the challenges and perspectives of DEG. We believe that DEG will play an important role in mechanical energy harvesting in the future.

Multiple Resonances Piezoelectric Energy Harvesting Generator

2009 ◽  
Author(s):  
Shaofan Qi ◽  
Roger Shuttleworth ◽  
S. Olutunde Oyadiji
Keyword(s):  
Energy Harvesting ◽  
Energy Harvester ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
Limited Bandwidth ◽  
Piezo Element ◽  
Piezoelectric Energy ◽  
Wide Range ◽  
Environmental Vibration ◽  
Design And Testing

Energy harvesting is the process of converting low level ambient energy into usable electrical energy, so that remote electronic instruments can be powered without the need for batteries or other supplies. Piezoelectric material has the ability to convert mechanical energy into electrical energy, and cantilever type harvesters using this material are being intensely investigated. The typical single cantilever energy harvester design has a limited bandwidth, and is restricted in ability for converting environmental vibration occurring over a wide range of frequencies. A multiple cantilever piezoelectric generator that works over a range of frequencies, yet has only one Piezo element, is being investigated. The design and testing of this novel harvester is described.

Handedness-controlled and solvent-driven actuators with twisted fibers

2019 ◽  
Vol 6 (6) ◽  
pp. 1207-1214 ◽  
Author(s):  
Bo Fang ◽  
Youhua Xiao ◽  
Zhen Xu ◽  
Dan Chang ◽  
Bo Wang ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Kinetic Energy ◽  
Energy Conversion ◽  
Conversion Coefficient ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
High Energy ◽  
Polar Solvents ◽  
Start Up

Handedness-controlled actuating systems are constructed from continuous twisted fibers with mirrored handedness, superb flexibility and mechanical robustness, affording impressive start-up torques driven by polar solvents, and controllably outputting rotor kinetic energy, harvesting electrical energy, and delivering mechanical energy with a high energy conversion coefficient.

Modeling of Inhomogeneous Deformation in a Dielectric Elastomer Generator for Energy Harvesting

2010 ◽  
Author(s):  
Tiefeng Li ◽  
Christoph Keplinger ◽  
Liwu Liu ◽  
Richard Baumgartner ◽  
Shaoxing Qu
Keyword(s):  
Energy Harvesting ◽  
Low Voltage ◽  
High Energy ◽  
Dielectric Elastomer ◽  
Optimal Operation ◽  
High Energy Density ◽  
Chamber Pressure ◽  
Inhomogeneous Deformation ◽  
Air Chamber ◽  
Compliant Electrodes

Dielectric elastomer transducers promise to combine high energy density at low cost and lightweight when used as actuators or for energy harvesting generators. A cornucopia of possible applications have been demonstrated over the last years including soft matter based actuators for robotics, tunable optics, medical devices, space robotics and energy harvesters. Prestretch effects and the electromechanical instability have been shown to highly influence the performance of dielectric elastomer transducers. Nevertheless only sparse research has been done on instability and prestretch effects of dielectric elastomer membranes under inhomogeneous deformation. Dielectric elastomer transducers consist of an elastomer membrane sandwiched between a pair of compliant electrodes and can be considered as deformable capacitors with variable capacitance. Here we focus on a specific experimental setup well suited to study the performance of dielectric elastomer materials for energy harvesting. In this setup an elastomer membrane is equibiaxially prestretched and fixed on top of an air chamber which is connected to a compressed air reservoir, the source of mechanical energy for thegenerator. From the electrical point of view the compliant electrodes on the elastomer membrane can be connected to both a high and low voltage charge reservoir. Thus the change in capacitance during deformation can be used to boost charges from the low voltage reservoir to the high voltage reservoir. Experimentally, different constant voltages are applied to the elastomer membrane during inflation and the air chamber pressure is recorded together with the shape and the volume of the balloon for different initial prestretches. The usual instability in the pressure-volume curves of ballon inflation experiments are shown to be influenced by applied voltage and prestretch. Theoretically, the setup is modeled as a thermodynamic system, with static electric and mechanical load where quasi-static equilibrium states can be achieved. To describe the inhomogeneous deformation and to correctly account for the hyperelastic behavior of the material over the whole deformation range an asymmetric model is built based on the Arruda-Boyce material model. The results of the numerical simulation are fitted to the experimental data to obtain significant material parameters in order to predict the optimal operation regime of the dielectric elastomer generator. The experimental results accompanied by the theoretical analysis may be used as a benchmark for the applicability of dielectric elastomer generators and pave ways for understanding the dielectric elastomer behavior under inhomogeneous deformation.

On the Lifetime Performance of a Styrenic Rubber Membrane for Dielectric Elastomer Transducers

2018 ◽  
Author(s):  
Chen Yi ◽  
Lorenzo Agostini ◽  
Marco Fontana ◽  
Giacomo Moretti ◽  
Rocco Vertechy
Keyword(s):  
Mechanical Energy ◽  
Experimental Studies ◽  
Electrical Energy ◽  
High Energy ◽  
Dielectric Elastomer ◽  
Rubber Membrane ◽  
Very High Energy ◽  
The Subject ◽  
Electrical Loads ◽  
Very High

Dielectric Elastomer Transducers (DETs) are solid-state electrostatic devices with variable capacitance that can convert electrical energy into mechanical energy and vice-versa. Recent theoretical and experimental studies demonstrated that DETs made of materials like silicone elastomer and natural rubber can operate at very high energy densities. Practical applicability of DETs is strongly affected by their reliability and lifetime, which depend on the maximum strain and electrical loads that are cyclically applied on such devices. To date, very little knowledge and experimental results are available on the subject. In this context, this paper reports on an extensive lifetime assessment campaign conducted on frame-stretched circular DET specimens made of a commercial styrenic rubber membrane subjected to cyclic electrical loading.

scholarly journals Deep Insight into the Influences of the Intrinsic Properties of Dielectric Elastomer on the Energy-Harvesting Performance of the Dielectric Elastomer Generator

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4202
Author(s):  
Yingjie Jiang ◽  
Yujia Li ◽  
Haibo Yang ◽  
Nanying Ning ◽  
Ming Tian ◽  
...  
Keyword(s):  
Energy Density ◽  
Energy Harvesting ◽  
Conversion Efficiency ◽  
High Energy ◽  
Dielectric Elastomer ◽  
High Energy Density ◽  
Breakdown Field ◽  
Intrinsic Properties ◽  
High Permittivity ◽  
The Relationship

The dielectric elastomer (DE) generator (DEG), which can convert mechanical energy to electrical energy, has attracted considerable attention in the last decade. Currently, the energy-harvesting performances of the DEG still require improvement. One major reason is that the mechanical and electrical properties of DE materials are not well coordinated. To provide guidance for producing high-performance DE materials for the DEG, the relationship between the intrinsic properties of DE materials and the energy-harvesting performances of the DEG must be revealed. In this study, a simplified but validated electromechanical model based on an actual circuit is developed to study the relationship between the intrinsic properties of DE materials and the energy-harvesting performance. Experimental verification of the model is performed, and the results indicate the validity of the proposed model, which can well predict the energy-harvesting performances. The influences of six intrinsic properties of DE materials on energy-harvesting performances is systematically studied. The results indicate that a high breakdown field strength, low conductivity and high elasticity of DE materials are the prerequisites for obtaining high energy density and conversion efficiency. DE materials with high elongation at break, high permittivity and moderate modulus can further improve the energy density and conversion efficiency of the DEG. The ratio of permittivity and the modulus of the DE should be tailored to be moderate to optimize conversion efficiency (η) of the DEG because using DE with high permittivity but extremely low modulus may lead to a reduction in η due to the occurrence of premature “loss of tension”.

scholarly journals Investigation of dielectric elastomer human energy harvesting to reduce knee joint torque deviation due to bracing

2019 ◽  
Vol 6 ◽  
pp. ???
Author(s):  
Heather Lai ◽  
Kristina Reid
Keyword(s):  
Energy Harvesting ◽  
Knee Joint ◽  
Electrical Energy ◽  
Dielectric Elastomer ◽  
The Body ◽  
Joint Torque ◽  
Knee Brace ◽  
Leg Extension ◽  
Human Energy Harvesting ◽  
Stiffness And Damping

Introduction The use of a smart electromechanical material, dielectric elastomer, is investigated for the development of an active bracing technique, which modifies the stiffness and damping of the knee brace during energy harvesting so as to reduce knee joint torque deviation during late swing in braced walking. Methods The bracing technique considered involves a dielectric elastomer energy harvesting cycle, which activates only when the knee flexor muscles are contracting eccentrically during late swing. The brace reduces the leg extension deviation during late swing in braced walking by transforming a portion of the mechanical stored energy into electrical energy, reducing the required internal work performed within the body. Results Simulated behavior of the dielectric elastomer brace worn across the knee joint demonstrates that when properly activated, the dielectric elastomer brace’s reduction in stiffness and increase in damping minimize the added energy expenditure of knee joint bracing during late swing. Conclusions The modeling results demonstrate the effective application of a soft, circumferential, dielectric elastomer energy harvesting knee brace, which utilizes the changes in the dynamic behavior of the knee joint occurring during energy harvesting in order to reduce the added demand placed on the knee joint under braced conditions.

Conductive, self-healing and recyclable electrodes for dielectric elastomer generator with high energy density

2022 ◽  
Vol 429 ◽  
pp. 132258
Author(s):  
Wenpeng Zang ◽  
Xueying Liu ◽  
Junjie Li ◽  
Yingjie Jiang ◽  
Bing Yu ◽  
...  
Keyword(s):  
Energy Density ◽  
High Energy ◽  
Dielectric Elastomer ◽  
High Energy Density ◽  
Self Healing

Temperature relaxation in strongly-coupled binary ionic mixtures

2021 ◽  
Author(s):  
Robert Sprenkle ◽  
Luciano Silvestri ◽  
M. S. Murillo ◽  
Scott Bergeson
Keyword(s):  
Material Properties ◽  
Inertial Confinement Fusion ◽  
Coulomb Systems ◽  
High Energy ◽  
High Energy Density ◽  
Inertial Confinement ◽  
Relaxation Rates ◽  
Strongly Coupled ◽  
Wide Range ◽  
Temperature Relaxation

Abstract New facilities such as the National Ignition Facility and the Linac Coherent Light Source have pushed the frontiers of high energy-density matter. These facilities offer unprecedented opportunities for exploring extreme states of matter, ranging from cryogenic solid-state systems to hot, dense plasmas, with applications to inertial-confinement fusion and astrophysics. However, significant gaps in our understanding of material properties in these rapidly evolving systems still persist. In particular, non-equilibrium transport properties of strongly-coupled Coulomb systems remain an open question. Here, we study ion-ion temperature relaxation in a binary mixture, exploiting a recently-developed dual-species ultracold neutral plasma. We compare measured relaxation rates with atomistic simulations and a range of popular theories. Our work validates the assumptions and capabilities of the simulations and invalidates theoretical models in this regime. This work illustrates an approach for precision determinations of detailed material properties in Coulomb mixtures across a wide range of conditions.

Energy Harvesting Under Harsh Conditions for the Oil & Gas Upstream Industry

2021 ◽  
Author(s):  
José Correia ◽  
Cátia Rodrigues ◽  
Ricardo Esteves ◽  
Ricardo Cesar Bezerra de Melo ◽  
José Gutiérrez ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Oil And Gas ◽  
Electrical Energy ◽  
Development Stage ◽  
Gas Extraction ◽  
Power Monitoring ◽  
Operational Conditions ◽  
Wide Range ◽  
First Time ◽  
Harsh Conditions

Abstract Environmental and safety sensing is becoming of high importance in the oil and gas upstream industry. However, present solutions to feed theses sensors are expensive and dangerous and there is so far no technology able to generate electrical energy in the operational conditions of oil and gas extraction wells. In this paper it is presented, for the first time in a relevant environment, a pioneering energy harvesting technology based on nanomaterials that takes advantage of fluid movement in oil extraction wells. A device was tested to power monitoring systems with locally harvested energy in harsh conditions environment (pressures up to 50 bar and temperatures of 50ºC). Even though this technology is in an early development stage this work opens a wide range of possible applications in deep underwater environments and in Oil and Gas extraction wells where continuous flow conditions are present.

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