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.

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.

Manufacture and Experimental Investigation of a Multi-Layer Generator Based on Dielectric Elastomer

2014 ◽  
Vol 960-961 ◽  
pp. 1336-1341
Author(s):  
Xue Jing Liu ◽  
Gong Zhang ◽  
Yong Quan Wang ◽  
Shu Hai Jia
Keyword(s):  
Energy Harvesting ◽  
Light Emitting Diode ◽  
Electrical Energy ◽  
Dielectric Elastomer ◽  
Maximum Energy ◽  
Open Circuit ◽  
Light Emitting ◽  
Energy Harvesting Efficiency ◽  
Open Circuit Condition ◽  
Constant Charge

As a member of Electroactive Polymers (EAPs), dielectric elastomer (DE) has shown considerable potential for energy harvesting applications. After the basic principle of DE energy harvesting is studied, a multi-layer DE generator using VHB 4910 (3M, USA) is specially designed and fabricated. Then, an improved energy harvesting circuit is designed to make use of harvested electrical energy. Finally, energy harvesting experiments are implemented under the constant charge (open-circuit) condition and the results prove that the multi-layer DE generator fabricated can produce enough energy to constantly drive a light emitting diode. The harvested electrical energy has good consistent with generated electrical energy and the maximum energy harvesting efficiency ηh can reach 89%.

scholarly journals Adaptive PEH-QoS Aware Management Control Scheme Based on Peltier and Piezoelectric Hybrid Model for WBAN Applications

2019 ◽  
Vol 8 (11) ◽  
pp. 89-94
Keyword(s):  
Energy Harvesting ◽  
Hybrid Approach ◽  
Threshold Level ◽  
Management Control ◽  
Packet Transmission ◽  
The Body ◽  
Sensor Nodes ◽  
Neighboring Node ◽  
Asthma Attack ◽  
Human Energy Harvesting

Energy harvesting in the medical field is a reliable and effective method to charge the body sensor nodes in Wireless Body Area Networks (WBANs) for medical applications. WBANs provides health monitoring with real time updates for patient’s record. In WBANs, the nodes are used to detect events, which give significant contribution to maintain the Quality of Service (QoS) demands in terms of delay in packet transmission and reception, throughput and packet loss during communication. However, harvesting energy from motion of human body with health is always a challenge for WBANs. This simply increases the need to apt a new hybrid approach of Peltier and Piezoelectric human energy harvesting model for WBANs application. In recent years, a lot of researches related to Piezoelectric and Peltier that are shown in this literature. This paper proposes a hybrid approach of Piezoelectric and Peltier sensors for a WBAN Application. Work involves energy harvesting from movements and temperature gradients (body to ambient). Moreover, to use both of energies at the same time needs effective algorithm which is possible with the optimized way proposed in this paper. Proposed work uses the approach to pass emergency data to neighboring nodes if neighboring node elected as forward node. Election of forward node is selected on the basis of threshold level (α). In WBAN systems criticalness of data depends upon the applications. There are some cases like heart attack, asthma attack, diabetic attack etc requires immediate attention. These cases are considered as critical in nature. As proposed work uses the concept of data forwarding even if the node has not the power to send data up to BNC. Using this concept node which needs to send critical/emergency packets with low battery condition is possible. Proposed approach enhances data delivery and reduces the packet drop

scholarly journals Emerging Energy Harvesting Technology for Electro/Photo-Catalytic Water Splitting Application

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 142
Author(s):  
Jianfei Tang ◽  
Tianle Liu ◽  
Sijia Miao ◽  
Yuljae Cho
Keyword(s):  
Energy Harvesting ◽  
Water Splitting ◽  
Social Impact ◽  
Electrical Energy ◽  
Future Research ◽  
Daily Lives ◽  
Energy Applications ◽  
Sustainable Environment ◽  
Energy Technologies ◽  
Splitting System

In recent years, we have experienced extreme climate changes due to the global warming, continuously impacting and changing our daily lives. To build a sustainable environment and society, various energy technologies have been developed and introduced. Among them, energy harvesting, converting ambient environmental energy into electrical energy, has emerged as one of the promising technologies for a variety of energy applications. In particular, a photo (electro) catalytic water splitting system, coupled with emerging energy harvesting technology, has demonstrated high device performance, demonstrating its great social impact for the development of the new water splitting system. In this review article, we introduce and discuss in detail the emerging energy-harvesting technology for photo (electro) catalytic water splitting applications. The article includes fundamentals of photocatalytic and electrocatalytic water splitting and water splitting applications coupled with the emerging energy-harvesting technologies using piezoelectric, piezo-phototronic, pyroelectric, triboelectric, and photovoltaic effects. We comprehensively deal with different mechanisms in water splitting processes with respect to the energy harvesting processes and their effect on the water splitting systems. Lastly, new opportunities in energy harvesting-assisted water splitting are introduced together with future research directions that need to be investigated for further development of new types of water splitting systems.

scholarly journals Identification of Dynamic Parameters of Pedestrian Walking Model Based on a Coupled Pedestrian–Structure System

2021 ◽  
Vol 11 (14) ◽  
pp. 6407
Author(s):  
Huiqi Liang ◽  
Wenbo Xie ◽  
Peizi Wei ◽  
Dehao Ai ◽  
Zhiqiang Zhang
Keyword(s):  
Negative Correlation ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Field Testing ◽  
The Body ◽  
Structural Vibration ◽  
Pedestrian Dynamics ◽  
Structure Interaction ◽  
Mass Spring ◽  
Stiffness And Damping

As human occupancy has an enormous effect on the dynamics of light, flexible, large-span, low-damping structures, which are sensitive to human-induced vibrations, it is essential to investigate the effects of pedestrian–structure interaction. The single-degree-of-freedom (SDOF) mass–spring–damping (MSD) model, the simplest dynamical model that considers how pedestrian mass, stiffness and damping impact the dynamic properties of structures, is widely used in civil engineering. With field testing methods and the SDOF MSD model, this study obtained pedestrian dynamics parameters from measured data of the properties of both empty structures and structures with pedestrian occupancy. The parameters identification procedure involved individuals at four walking frequencies. Body frequency is positively correlated to the walking frequency, while a negative correlation is observed between the body damping ratio and the walking frequency. The test results further show a negative correlation between the pedestrian’s frequency and his/her weight, but no significant correlation exists between one’s damping ratio and weight. The findings provide a reference for structural vibration serviceability assessments that would consider pedestrian–structure interaction effects.

Experimental Research of Energy Harvesting and Storage Based on Ferroelectric Materials

2012 ◽  
Vol 476-478 ◽  
pp. 1336-1340
Author(s):  
Kai Feng Li ◽  
Rong Liu ◽  
Lin Xiang Wang
Keyword(s):  
Energy Harvesting ◽  
Electromagnetic Waves ◽  
Vibrational Energy ◽  
Waste Heat ◽  
Mechanical Strain ◽  
Electrical Potential ◽  
Electrical Energy ◽  
Ferroelectric Materials ◽  
Energy Scavenging ◽  
And Storage

The concept of energy harvesting works towards developing self-powered devices that do not require replaceable power supplies. Energy scavenging devices are designed to capture the ambient energy surrounding the electronics and convert it into usable electrical energy. A number of sources of harvestable ambient energy exist, including waste heat, vibration, electromagnetic waves, wind, flowing water, and solar energy. While each of these sources of energy can be effectively used to power remote sensors, the structural and biological communities have placed an emphasis on scavenging vibrational energy with ferroelectric materials. Ferroelectric materials have a crystalline structure that provide a unique ability to convert an applied electrical potential into a mechanical strain or vice versa. Based on the properties of the material, this paper investigates the technique of power harvesting and storage.

BIOMECHANICAL ANALYSIS OF THE STANDING LONG JUMP

2003 ◽  
Vol 15 (05) ◽  
pp. 186-192 ◽  
Author(s):  
WEN-LAN WU ◽  
JIA-HROUNG WU ◽  
HWAI-TING LIN ◽  
GWO-JAW WANG
Keyword(s):  
Knee Joint ◽  
Motion Analysis ◽  
Joint Angle ◽  
Three Dimensional ◽  
The Body ◽  
Initial Angle ◽  
Knee Joint Angle ◽  
Standing Long Jump ◽  
Long Jump ◽  
Arm Motion

The purposes of the present study were to (1) investigate the effects of the arm movement and initial knee joint angle employed in standing long jump by the ground reaction force analysis and three-dimensional motion analysis; and (2) investigate how the jump performance of the female gender related to the body configuration. Thirty-four healthy adult females performed standing long jump on a force platform with full effort. Body segment and joint angles were analyzed by three-dimensional motion analysis system. Using kinetic and kinematic data, the trajectories on mass center of body, knee joint angle, magnitude of peak takeoff force, and impulse generation in preparing phase were calculated. Average standing long jump performances with free arm motion were +1.5 times above performance with restricted arm motion in both knee initial angles. The performances with knee 90° initial flexion were +1.2 times above performance with knee 45° initial flexion in free and restricted arm motions. Judging by trajectories of the center mass of body (COM), free arm motion improves jump distance by anterior displacement of the COM in starting position. The takeoff velocity with 90° knee initial angle was as much as 11% higher than in with 45° knee initial angle. However, the takeoff angles on the COM trajectory showed no significant differences between each other. It was found that starting jump from 90° bend knee relatively extended the time that the force is applied by the leg muscles. To compare the body configurations and the jumping scores, there were no significant correlations between jump scores and anthropometry data. The greater muscle mass or longer leg did not correlated well with the superior jumping performance.

Note: Analysis of the efficiency of a dielectric elastomer generator for energy harvesting

2011 ◽  
Vol 82 (4) ◽  
pp. 046101 ◽  
Author(s):  
Gyungsoo Kang ◽  
Kyung-Soo Kim ◽  
Soohyun Kim
Keyword(s):  
Energy Harvesting ◽  
Dielectric Elastomer

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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