Electrorheological Fluids of GO/Graphene-Based Nanoplates

Due to their unique anisotropic morphology and properties, graphene-based materials have received extensive attention in the field of smart materials. Recent studies show that graphene-based materials have potential application as a dispersed phase to develop high-performance electrorheological (ER) fluids, a kind of smart suspension whose viscosity and viscoelastic properties can be adjusted by external electric fields. However, pure graphene is not suitable for use as the dispersed phase of ER fluids due to the electric short circuit caused by its high electrical conductivity under electric fields. However, graphene oxide (GO) and graphene-based composites are suitable for use as the dispersed phase of ER fluids and show significantly enhanced property. In this review, we look critically at the latest developments of ER fluids based on GO and graphene-based composites, including their preparation, electrically tunable ER property, and dispersed stability. The mechanism behind enhanced ER property is discussed according to dielectric spectrum analysis. Finally, we also propose the remaining challenges and possible developments for the future outlook in this field.

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THE ELECTRORHEOLOGICAL FLUIDS WITH HIGH SHEAR STRESS

International Journal of Modern Physics B ◽

10.1142/s0217979205029869 ◽

2005 ◽

Vol 19 (07n09) ◽

pp. 1065-1070 ◽

Cited By ~ 28

Author(s):

KUNQUAN LU ◽

RONG SHEN ◽

XUEZHAO WANG ◽

GANG SUN ◽

WEIJIA WEN

Keyword(s):

Shear Stress ◽

Electric Field ◽

Yield Stress ◽

High Performance ◽

Electrorheological Fluids ◽

Stress Effect ◽

High Shear ◽

High Shear Stress ◽

Effective Factors ◽

Er Fluids

A series of high performance ER fluids newly manufactured in our laboratory are presented. The yield stress of those ER fluids can reach several tens of kPa, 100 kPa and even 200 kPa, respectively. For understanding the high shear stress effect a model is proposed base on the electric field induced molecular bounding effect. The main effective factors in fabricating the high performance ER are discussed.

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Surface Feedback for Virtual Environment Systems Using Electrorheological Fluids

International Journal of Modern Physics B ◽

10.1142/s0217979296001458 ◽

1996 ◽

Vol 10 (23n24) ◽

pp. 3011-3018 ◽

Cited By ~ 19

Author(s):

P.M. Taylor ◽

A. Hosseini-Sianaki ◽

C.J. Varley

Keyword(s):

Experimental Study ◽

Information System ◽

Virtual Environment ◽

Electric Fields ◽

Electrorheological Fluids ◽

Different Types ◽

Flexible Designs ◽

Er Fluids ◽

The Given

A tactile array system, when incorporated in an information system, provides a means of conveying tactile data to the user. Such arrays have many applications including simulators for training purposes and Braille systems for the blind. The use of ER fluids in these systems would provide an inexpensive alternative to the existing technologies because of the simple and flexible designs. An experimental study has been conducted which involves a simple 5×5 array of tactels, each tactel being independently energised in order to configure a variety of shapes. A series of tests are carried out on two different types of ER fluids under a range of electric fields and sensor speeds. The results show that for the given tactel spacing, the programmed shapes are easily detected for all conditions and are directly comparable to similar tests undertaken on a solid shape.

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YIELD STRESS MODELING OF ELECTRORHEOLOGICAL FLUIDS USING NEURAL NETWORK

International Journal of Modern Physics B ◽

10.1142/s0217979205032620 ◽

2005 ◽

Vol 19 (27) ◽

pp. 4093-4102

Author(s):

KEXIANG WEI ◽

GUANG MENG

Keyword(s):

Neural Network ◽

Theoretical Model ◽

Yield Stress ◽

Electric Fields ◽

Smart Materials ◽

Back Propagation ◽

Industrial Applications ◽

Operating Conditions ◽

Back Propagation Algorithm ◽

Er Fluids

Electrorheological (ER) fluids are a kind of smart materials whose rheological properties can be rapidly changed by applied electric fields. Many potential industrial applications of ER technology have been proposed. In order to formulate better ER fluids and design ER devices, it is important to predict the yield stress of ER fluids based on the ER fluids components and the operating conditions. This paper proposes a new method for predicting the yield stress of ER fluids with neural network (NN). A multilayer perceptron with a single hidden layer of neurons is used to model the ER effect. The data for training and test were produced from the simulation of previous proposed mathematical models. The Levernberg–Marquardt back propagation algorithm was selected for fast learning. The results show the neural network model can well approximate the previous theoretical model, and the predicted outputs of NN agree nearly with the theoretical model values under the same input, all of which demonstrate that it is possible to generate a robust NN model for rapidly predicting the yield stress of ER fluids under different input parameters.

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POLAR MOLECULE TYPE ELECTRORHEOLOGICAL FLUIDS

International Journal of Modern Physics B ◽

10.1142/s0217979207045682 ◽

2007 ◽

Vol 21 (28n29) ◽

pp. 4798-4805 ◽

Cited By ~ 13

Author(s):

KUNQUAN LU ◽

RONG SHEN ◽

XUEZHAO WANG ◽

GANG SUN ◽

WEIJIA WEN ◽

...

Keyword(s):

Electric Field ◽

High Performance ◽

Polar Molecule ◽

Electrorheological Fluids ◽

High Yield ◽

Polar Molecules ◽

Dynamic Shear ◽

Effective Factors ◽

Er Fluids ◽

Molecule Type

The static and dynamic shear stress of newly developed electrorheological (ER) fluids can reach more than 100 kPa and over 60 kPa at 3 kV/mm, respectively. The high yield stress of those ER fluids and its near linear dependence on the electric field are different from the conventional ER fluids and can not be explained with traditional dielectric theory. Experiment demonstrates that the polar molecules adsorbed on the particles play crucial role in those ER fluids, which can be named as polar molecule type electrorheological (PM-ER) fluids. To explain PM-ER effect a model is proposed based on the interaction of polar molecule-charge in between the particles, where the local electric field is much higher than the external one and can cause the polar molecules aligning. The main effective factors for achieving high-performance PM-ER fluids are discussed.

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PRACTICE-RELEVANT ASPECTS OF CONSTRUCTING ER FLUID ACTUATORS

International Journal of Modern Physics B ◽

10.1142/s0217979296001690 ◽

1996 ◽

Vol 10 (23n24) ◽

pp. 3243-3255 ◽

Cited By ~ 8

Author(s):

H. Janocha ◽

B. Rech ◽

R. Bölter

Keyword(s):

Electric Fields ◽

Electrorheological Fluids ◽

Flow Mode ◽

Process Automation ◽

Rotational Viscometer ◽

Energy Transducer ◽

The Individual ◽

Er Fluids ◽

The University ◽

Er Fluid

The flow resistance of electrorheological fluids (ER fluids) can be controlled by applying electric fields. Thus, ER fluids are suitable for the application in actuators, using high-voltage sources for the generation of the field. The behaviour of an ER fluid actuator not only depends on the properties of the individual actuator components (ER fluid, energy transducer and energy source) but especially on their combined efforts as a system. Based on a possible scheme for the design of ER fluid actuators, this paper presents important practice-relevant aspects of a systematic actuator construction. Here the behaviour of a commercial ER suspension is examined and compared to a homogeneous ER fluid without yield point using a rotational viscometer and a flow-mode damper realized at the Laboratory of Process Automation (LPA) of the University of Saarland.

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High-Performance Micro-Electrohydrodynamic Pump Actuator

Volume 5: 19th Biennial Conference on Mechanical Vibration and Noise, Parts A, B, and C ◽

10.1115/detc2003/vib-48543 ◽

2003 ◽

Author(s):

Kazim M. Ali ◽

Reza Kashani ◽

Kevin Hallinan

Keyword(s):

Electric Fields ◽

Smart Materials ◽

High Performance ◽

Active Vibration Control ◽

Dielectric Fluid ◽

Noise Abatement ◽

Fluid Medium ◽

Active Structure ◽

Magnetostrictive Actuators ◽

Active Vibration

The research aims at building a highly effective, miniaturized electrohydrodynamic pumped actuator. The actuator would provide greater performance in terms of higher force, higher displacement and equivalent bandwidth to the so-called smart materials (piezoelectric and magnetostrictive) actuators of comparable size. The EHD actuators find applications in active structure-borne noise abatement, active vibration control, precision pointing. The on-going research aims at parametrically understanding the actuator with respect to its geometry, contained dielectric fluid medium and electric fields. A multitude of prototypes will be designed, fabricated and tested to provide experimental benchmarking of the model predictions. At the same time, this experimental bench marking will provide practical expertise in both fabricating the concept and incorporating it into smart structures.

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Antireflection Improvement and Junction Quality Optimization of Si/PEDOT:PSS Solar Cell with the Introduction of Dopamine@Graphene

Energies ◽

10.3390/en13225986 ◽

2020 ◽

Vol 13 (22) ◽

pp. 5986

Author(s):

Tao Chen ◽

Hao Guo ◽

Leiming Yu ◽

Tao Sun ◽

Anran Chen ◽

...

Keyword(s):

Solar Cell ◽

Conversion Efficiency ◽

High Performance ◽

Electrochemical Impedance ◽

Short Circuit ◽

Short Circuit Current ◽

Electrochemical Impedance Spectra ◽

Solar Cell Performance ◽

Photovoltaic Conversion ◽

Photovoltaic Conversion Efficiency

Si/PEDOT: PSS solar cell is an optional photovoltaic device owing to its promising high photovoltaic conversion efficiency (PCE) and economic manufacture process. In this work, dopamine@graphene was firstly introduced between the silicon substrate and PEDOT:PSS film for Si/PEDOT: PSS solar cell. The dopamine@graphene was proved to be effective in improving the PCE, and the influence of mechanical properties of dopamine@graphene on solar cell performance was revealed. When dopamine@graphene was incorporated into the cell preparation, the antireflection ability of the cell was enhanced within the wavelength range of 300~450 and 650~1100 nm. The enhanced antireflection ability would benefit amount of the photon-generated carriers. The electrochemical impedance spectra test revealed that the introduction of dopamine@graphene could facilitate the separation of carriers and improve the junction quality. Thus, the short-circuit current density and fill factor were both promoted, which led to the improved PCE. Meanwhile, the influence of graphene concentration on device performances was also investigated. The photovoltaic conversion efficiency would be promoted from 11.06% to 13.15% when dopamine@graphene solution with concentration 1.5 mg/mL was applied. The achievements of this study showed that the dopamine@graphene composites could be an useful materials for high-performance Si/PEDOT:PSS solar cells.

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High performance tandem organic solar cells via a strongly infrared-absorbing narrow bandgap acceptor

Nature Communications ◽

10.1038/s41467-020-20431-6 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Zhenrong Jia ◽

Shucheng Qin ◽

Lei Meng ◽

Qing Ma ◽

Indunil Angunawela ◽

...

Keyword(s):

Solar Cells ◽

Power Conversion Efficiency ◽

Conversion Efficiency ◽

Organic Solar Cells ◽

High Performance ◽

Short Circuit ◽

Power Conversion ◽

High Power Conversion Efficiency ◽

Device Structure ◽

Narrow Bandgap

AbstractTandem organic solar cells are based on the device structure monolithically connecting two solar cells to broaden overall absorption spectrum and utilize the photon energy more efficiently. Herein, we demonstrate a simple strategy of inserting a double bond between the central core and end groups of the small molecule acceptor Y6 to extend its conjugation length and absorption range. As a result, a new narrow bandgap acceptor BTPV-4F was synthesized with an optical bandgap of 1.21 eV. The single-junction devices based on BTPV-4F as acceptor achieved a power conversion efficiency of over 13.4% with a high short-circuit current density of 28.9 mA cm−2. With adopting BTPV-4F as the rear cell acceptor material, the resulting tandem devices reached a high power conversion efficiency of over 16.4% with good photostability. The results indicate that BTPV-4F is an efficient infrared-absorbing narrow bandgap acceptor and has great potential to be applied into tandem organic solar cells.

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