Dynamic-coupling analyses of cells localization by the negative dielectrophoresis

2020 ◽  
pp. 095440622092905
Author(s):  
Jianlong Ji ◽  
Jingxiao Wang ◽  
Liu Wang ◽  
Qiang Zhang ◽  
Qianqian Duan ◽  
...  
Keyword(s):  
Coupling Effect ◽  
Electrode Spacing ◽  
Cell Diameter ◽  
Specific Cell ◽  
Dynamic Coupling ◽  
Ac Electroosmosis ◽  
Ac Electrokinetics ◽  
Cell Localization ◽  
Electrothermal Flow ◽  
Medium Conductivity

Negative dielectrophoresis is widely used in cell localization for long-term observations such as the impedance analysis, in vivo drug screening, and cell patterns. However, the coupling effect of AC electrokinetics, including negative dielectrophoresis, AC electroosmosis, and electrothermal flow is still unclear. This work investigated cell localization based on the dynamic-coupling of dielectrophoresis, AC electroosmosis, and electrothermal flow. A two-dimensional finite element model that consisted of interdigitated array electrodes was established. The effects of system parameters on the capture efficiency were investigated, when the medium conductivity was in the range of 0.001–1 S/m. The selection of the medium conductivity is suggested to be the first step of the experiment design. Then, the choice of AC frequency and AC amplitude requires balancing the effects of transmembrane potential and temperature rise on cell viability. Besides, particular electrode spacing is evidenced to be only efficient for a specific cell diameter. Thus, the electrode spacing of the microfluidic chip needs to be optimized according to the cell's diameter.

AC Electrokinetics for Biosensors

2004 ◽  
Author(s):  
M. Sigurdson ◽  
C. Meinhart ◽  
D. Wang
Keyword(s):  
Electric Fields ◽  
Dna Hybridization ◽  
Fluid Motion ◽  
Diffusive Transport ◽  
Analyte Concentration ◽  
Ac Electrokinetics ◽  
Ac Electric Fields ◽  
Binding Rate ◽  
Electrothermal Flow ◽  
Biosensor Device

We develop here tools for speeding up binding in a biosensor device through augmenting diffusive transport, applicable to immunoassays as well as DNA hybridization, and to a variety of formats, from microfluidic to microarray. AC electric fields generate the fluid motion through the well documented but unexploited phenomenon, Electrothermal Flow, where the circulating flow redirects or stirs the fluid, providing more binding opportunities between suspended and wall-immobilized molecules. Numerical simulations predict a factor of up to 8 increase in binding rate for an immunoassay under reasonable conditions. Preliminary experiments show qualitatively higher binding after 15 minutes. In certain applications, dielectrophoretic capture of passing molecules, when combined with electrothermal flow, can increase local analyte concentration and further enhance binding.

Manipulation of Clinical Materials Using AC Electrokinetics

2010 ◽  
Author(s):  
Mandy L. Y. Sin ◽  
Pak Kin Wong
Keyword(s):  
Experimental Data ◽  
Sample Preparation ◽  
Theoretical Prediction ◽  
Fluid Motion ◽  
Lab On A Chip ◽  
Clinical Samples ◽  
Electrochemical Reactions ◽  
Ac Electrokinetics ◽  
Wide Range ◽  
Electrothermal Flow

AC electrokinetics is a promising approach for sample preparation and reaction enhancement in lab-on-a-chip devices. However, relative little has been done on the electrokinetic manipulation of physiological fluids and buffers with similar properties, such as conductivity. Herein, electrokinetic manipulation of fluids with a wide range of conductivities has been studied as a function of voltage and frequency. AC electrothermal flow is determined to dominate the fluid motion when the applied frequency of the AC potential is above 100 kHz. Interestingly, experimental data deviate from theoretical prediction for fluids with high conductivities (> 1 Sm−1). The deviation can be understood by voltage modulated electrochemical reactions and should be accounted for when manipulating clinical materials with high conductivities. The study will provide useful in sights in designing lab-on-a-chip devices for manipulating clinical samples in the future.

Sloshing Effects Accounting for Dynamic Coupling Between Vessel and Tank Liquid Motion

2007 ◽  
Author(s):  
Mirela Zalar ◽  
Louis Diebold ◽  
Eric Baudin ◽  
Jacqueline Henry ◽  
Xiao-Bo Chen
Keyword(s):  
Coupling Effect ◽  
Scale Model ◽  
Small Scale ◽  
Induced Response ◽  
Linear Potential ◽  
Dynamic Coupling ◽  
Liquid Motion ◽  
Violent Behaviour ◽  
Standard Size ◽  
Vessel Motion

Sloshing, a violent behaviour of liquid contents in tanks submitted to the forced vessels’ motion on the sea represents one of the major considerations in LNG vessels design over several past decades. State of the art of sloshing analysis relies on small-scale sloshing model tests supported by extensive developments of CFD computation techniques, commonly studying one isolated tank submitted to the forced motion without their mutual interaction. In reality, wave-induced response of the vessel carrying liquid cargo is affected by internal liquid motion, and consequently, tank liquid flow is altered by the vessel motion in return. An efficient numerical model for dynamic coupling between motions exerted by tank liquid (sloshing) and rigid body motions of the vessel (seakeeping) was developed in Bureau Veritas, formulated under the assumptions of linear potential theory in frequency domain. As already experienced with anti-rolling tanks, strong coupling effect is perceived on the first order transverse motions. However, consequences of coupled motions on sloshing loads have not been explored yet. This paper presents comparative analysis of sloshing effects induced by coupled and non-coupled vessel motion, introduced as the excitation to 6 d.o.f. small-scale model test rig. Possible risk of coupled effects is demonstrated on the example of standard size of LNG carrier operating with partly filled cargo tanks.

Two-Color Micro PIV Measurements of Particle and Fluid Motion in AC Electrokinetics

Materials ◽  
2003 ◽  
Author(s):  
Dazhi Wang ◽  
Carl Meinhart ◽  
Marin Sigurdson
Keyword(s):  
Electric Fields ◽  
Fluorescent Dyes ◽  
Fluid Velocity ◽  
A Priori ◽  
Fluid Motion ◽  
Ac Electroosmosis ◽  
Ac Electrokinetics ◽  
Piv Measurements ◽  
Drag Forces ◽  
Micro Piv

Two-Color μ-PIV is developed and used to uniquely determine the fluid velocity based on the micron-resolution Particle Image Velocimetry (μ-PIV) technique [1–3]. The fluid velocity field was obtained by measuring the motion of two different sizes particles, 0.7 and 1.0 μm. The different sizes of particles contain different fluorescent dyes, allowing them to be distinguished using fluorescent filter cubes. By comparing the velocity fields from the two different size particles, the underlying fluid motion can be uniquely determined, without a priori knowledge of the electrical properties of the particles, or the electrical field. The test section is formed by two wedge-shaped electrodes sandwiched between two glass wafers. In the presence of nonuniform ac electric fields, the particles experience dielectrophoretic (DEP) forces due to polarization and drag forces due to viscous interaction with the suspending medium, and the fluid motion is induced by the electrothermal effect and/or ac electroosmosis. The micro-PIV measurements are used to determine quantitatively the physical characteristics of the AC electrokinetic effects.

Biological Applications of Programmable Optoelectrofluidic Manipulation

2009 ◽  
Vol 1173 ◽  
Author(s):  
Je-Kyun Park
Keyword(s):  
Liquid Crystal Display ◽  
Particle Diameter ◽  
Discrimination Performance ◽  
Local Concentration ◽  
Display Device ◽  
Ac Electroosmosis ◽  
Friction Forces ◽  
Ac Electrokinetics ◽  
Virtual Electrodes

AbstractThis paper presents a new programmable particle manipulation using a lab-on-a-display platform, which is a kind of optoelectrofluidic platform applying a liquid crystal display (LCD) as a display device for generating virtual electrodes in optoelectronic tweezers. The reconfigurable virtual electrodes in the lab-on-a-display are more advantageous than other devices which apply the micro-patterned electrodes, because we can freely control the size and position of electrodes as well as the voltage conditions, which affect the particle movements such as concentration and separation of particles. Due to its simple structures, cheap manufacturing costs, and high performances, this new LCD-based optoelectrofluidic platform can be applied to the interactive manipulation of polystyrene microspheres and blood cells. In addition, a method to discriminate normal oocytes for in vitro fertilization is demonstrated by combining the gravity effect with the optically induced positive dielectrophoresis (DEP). The discrimination performance can be enhanced due to the reduction of friction forces acting on the oocytes which are relatively large and heavy cells being affected by the gravity field. With the same device, we also demonstrate the size-dependent microparticle separation as well as the local concentration and assembly of microparticles originated from the image-driven AC electrokinetics such as DEP and AC electroosmosis. The particle movements result from the frequency-dependent behavior according to the particle diameter. This novel technique can be applied to rapidly concentrate, separate and pattern micro-/nanoparticles and biomolecules in many biological and chemical applications.

Cable arrangement to reduce electromagnetic coupling effects in spectral-induced polarization studies

Geophysics ◽  
2014 ◽  
Vol 79 (2) ◽  
pp. A1-A5 ◽  
Author(s):  
Myriam Schmutz ◽  
Ahmad Ghorbani ◽  
Pierre Vaudelet ◽  
Amélie Blondel
Keyword(s):  
Coupling Effect ◽  
Electromagnetic Coupling ◽  
Induced Polarization ◽  
Electrode Spacing ◽  
Coupling Effects ◽  
Array Type ◽  
Spectral Induced Polarization ◽  
Computer Codes ◽  
Lateral Offset ◽  
Phase Angles

Spectral-induced polarization (SIP) is widely used for environmental and engineering geophysical prospecting and hydrogeophysics, but one major limitation concerns the electromagnetic (EM) coupling effect. The phase angles related to EM coupling may increase even at frequencies as low as 1 Hz, depending on the ground resistivity, the array type, and the geometry. Most efforts to understand and quantify the EM coupling problem (e.g., theory and computer codes) have been developed for dipole-dipole arrays. However, we used a Schlumberger array to acquire SIP data. We found that with this array, the use of an appropriate cable arrangement during data acquisition can reduce EM coupling effects in the same proportion as for the use of a dipole-dipole array, which is the pure response of the studied earth. To measure the influence of the cable layout, four cable configurations with the same electrode spacing were compared for modeling and experimental data. We discovered that the classical DC inline array was the worst one. As soon as the cables were arranged in another shape (triangle or rectangle), the coupling effect decreased significantly. The best configuration we checked was the rectangular one with an acquisition unit located at a lateral offset of 100 m from the electrode line, even if there was still some difference between the modeled and measured data.

Rigid–flexible coupled dynamic response of steel–concrete bridges on expressways considering vehicle–road–bridge interaction

2019 ◽  
Vol 23 (1) ◽  
pp. 160-173
Author(s):  
Enli Chen ◽  
Xia Zhang ◽  
Gaolei Wang
Keyword(s):  
Dynamic Response ◽  
Mechanical Response ◽  
Coupling Effect ◽  
Interaction Model ◽  
Coupling Model ◽  
Concrete Bridges ◽  
Dynamic Coupling ◽  
Vehicle Model ◽  
Flexible Coupling ◽  
Bridge Model

Steel–concrete bridges on highways are now widely used, and their dynamic coupling effect is more prominent under heavy vehicles. At present, for the study of vehicle–bridge coupling, it is difficult to reflect the mechanical response characteristics of the bridge pavement because the bridge pavement (road) is often considered as a load. In order to get closer to reality, we use the whole vehicle model and the bridge model to realize the dynamic coupling of highway vehicle–bridge. Moreover, the vehicle model can take into account tire characteristics, such as various linear and nonlinear suspension characteristics, and tire–ground contact characteristics. So, a new vehicle–road–bridge interaction method with higher computational efficiency is proposed. This method can be used not only to analyze the overall mechanical response of bridge structure such as deflection and stress but also to analyze the dynamic characteristics of driving vehicles and the coupling force between tires and pavement and then to analyze the dynamic deformation and stress of asphalt pavement layers on the bridge. First, according to the construction drawings of a steel–concrete bridge on a highway and a Dongfeng brand three-axle vehicle, a vehicle–road–bridge interaction rigid–flexible coupling model was established. Second, the correctness and effectiveness of the vehicle–road–bridge interaction model were verified by field testing. Finally, the dynamic response of the vehicle–road–bridge interaction rigid–flexible coupling model was analyzed.

DC-Biased AC Electrokinetics Effect on V-Shaped Electrode Patterns for Microfluidics Applications

2019 ◽  
Author(s):  
Mohammad Salman Parvez ◽  
Mohammad Fazlay Rubby ◽  
Samir Iqbal ◽  
Nazmul Islam
Keyword(s):  
Research Work ◽  
Hydrophobic Surface ◽  
Surface Characteristics ◽  
The Other ◽  
Uniform Electric Field ◽  
Heat Sources ◽  
Ac Electroosmosis ◽  
Ac Electrokinetics ◽  
Mechanical Parts ◽  
Spatially Varying

Abstract AC electrokinetics is one of the widely used methods as an actuating mechanism in the lab-on-a-chip devices because of the absence of moving mechanical parts. In this paper, an analysis is done by using two perpendicular electrodes which are placed in V-shape to each other while maintaining an angle of 45 degrees with the third horizontal electrode. A semiconductive fluid was used to observe the microfluidic behavior and characteristics under the application of a DC biased AC signal. Applying the AC signal produced two different mechanisms of electrokinetics such as DC-biased AC electrothermal (ACET) and DC-biased AC electroosmosis (ACEO). In the ACEO process, a time-varying voltage was applied to the electrodes to create the double layer capacitance and zeta potential. This ACEO mechanism required lower voltage. On the other hand, the AC Electrothermal (ACET) flow produced a non-uniform electric field that generated spatially varying heat sources which in turn created a non-uniform temperature distribution. Two surface characteristics were also analyzed experimentally; one of these was by using the hydrophobic surface and the other used glass-surface only. At the microscale, mechanical microdevice encounter very high flow resistance and put stringent requirements on the strength of fluid channels, chambers and the interconnects. While many types of microfluidic manipulations can be effectively done by AC electrokinetics techniques, current research work focused on the observation of varying frequencies and voltages and their effects on microfluidic manipulations.

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