Controlled Separation and Trapping of Particles Using Two-frequency DEP

We present numerical simulations and experiments on dielectrophoretic (DEP) separation and trapping performed in a titanium-based microchannel linear electrode array. The use of electric fields and in particular dielectrophoresis (DEP) have a great potential to help miniaturize and increase the speed of biomedical analysis. Precise control and manipulation of micro/nano/bio particles inside those miniaturized devices depend greatly on our understanding of the phenomena induced by AC electric fields inside microchannels and how we take advantage of them. The studied DEP devices are composed of two parts: the inter-digitated titanium electrodes and the channel. The electrode substrate is constituted of two layers to form 4-phase traveling wave. Each electrode is 20 μm wide and separated from the other by a gap of 20 μm. The channel is 200 μm wide, 50 μm deep and 6 mm long. The device is designed to generate inhomogeneities in electric-field magnitude. This allows positive and negative DEP (p-DEP and n-DEP). Moreover, it can also produce inhomogeneities in electric-field phase, hence authorizing traveling wave DEP (twDEP). It is also capable of inducing two-frequency DEP, in contrast with most of the previous, single-frequency, designs. The advantages of two-frequency DEP were shown by theoretical work (Chang et al. 2003) and permit precise and optimal control of particles movements. We show that fluid flow effects are substantial and can affect the particle motion in a positive (enhanced trapping) and negative (trapping when separation is desired) way. We discuss the effects of AC-electroosmosis, electrothermal and dielectrophoresis combined. We discuss the advantages of two-frequency dielectrophoretic handling of bioparticles. We investigate the limits of particle size that can be accurately controlled.

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Electric Field-Assisted Positioning of Neurons on Pt Microelectrode Arrays

MRS Proceedings ◽

10.1557/proc-773-n4.6 ◽

2003 ◽

Vol 773 ◽

Author(s):

Shalini Prasad ◽

Mo Yang ◽

Xuan Zhang ◽

Yingchun Ni ◽

Vladimir Parpura ◽

...

Keyword(s):

Electric Field ◽

Electrical Activity ◽

Electric Fields ◽

Microelectrode Array ◽

Electrode Array ◽

Sprague Dawley ◽

A Cell ◽

Neuron Patterning

AbstractCharacterization of electrical activity of individual neurons is the fundamental step in understanding the functioning of the nervous system. Single cell electrical activity at various stages of cell development is essential to accurately determine in in-vivo conditions the position of a cell based on the procured electrical activity. Understanding memory formation and development translates to changes in the electrical activity of individual neurons. Hence, there is an enormous need to develop novel ways for isolating and positioning individual neurons over single recording sites. To this end, we used a 3x3 multiple microelectrode array system to spatially arrange neurons by applying a gradient AC field. We characterized the electric field distribution inside our test platform by using two dimensiona l finite element modeling (FEM) and determined the location of neurons over the electrode array. Dielectrophoretic AC fields were utilized to separate the neurons from the glial cells and to position the neurons over the electrodes. The neurons were obtained from 0-2-day-old rat (Sprague-Dawley) pups. The technique of using electric fields to achieve single neuron patterning has implications in neural engineering, elucidating a new and simpler method to develop and study neuronal activity as compared to conventional microelectrode array techniques.

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ELECTRIC FIELD INFLUENCE ON TRAVELING WAVE PROPAGATION AND STATIONARY PATTERN FORMATION

International Journal of Bifurcation and Chaos ◽

10.1142/s0218127495000582 ◽

1995 ◽

Vol 05 (03) ◽

pp. 797-807 ◽

Cited By ~ 2

Author(s):

J. MOSQUERA ◽

M. GÓMEZ-GESTEIRA ◽

V. PÉREZ-MUÑUZURI ◽

A.P. MUÑUZURI ◽

V. PÉREZ-VILLAR

Keyword(s):

Wave Propagation ◽

Pattern Formation ◽

Electric Field ◽

Electric Fields ◽

Traveling Wave ◽

Traveling Fronts ◽

Spatial Terms ◽

Oregonator Model ◽

Field Influence ◽

Good Agreement

The electric field influence on pattern formation and traveling wave propagation is investigated in the framework of the Oregonator model. When an electric field is applied to a system that can suffer spatial instabilities, Turing and Turing-like patterns (traveling fronts that become stationary patterns when reaching a zero-flux boundary) are observed. On the other hand, when an electric field is applied to a system that cannot become unstable by spatial terms and where wavefronts are propagating in the absence of electric fields, the velocity of these wavefronts is modified and can even be reversed. This is in good agreement with previous experimental results.

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Electrode Cooling Effect on Out-of-Phase Electrothermal Streaming in Rotating Electric Fields

10.20944/preprints201709.0137.v1 ◽

2017 ◽

Author(s):

Weiyu Liu ◽

Yukun Ren ◽

Ye Tao ◽

Xiaoming Chen ◽

Qisheng Wu

Keyword(s):

Electric Field ◽

Electric Fields ◽

Heat Dissipation ◽

Electrode Array ◽

Substrate Material ◽

Microfluidic Chips ◽

Metal Electrodes ◽

Bulk Fluid ◽

Dependent Flow ◽

Electrothermal Flow

In this work, we focus on investigating electrothermal flow in a rotating electric field (ROT-ETF), with primary attention paid to the horizontal traveling-wave electrothermal (TWET) vortex induced at the center of the electric field. The frequency-dependent flow profiles in the microdevice are analyzed using different heat transfer models. Accordingly, we address in particular the importance of electrode cooling in ROT-ETF as metal electrodes of high thermal conductivity while substrate material of low heat dissipation capability are employed to develop such microfluidic chips. Under this circumstance, cooling of electrode array due to external natural convection on millimeter-scale electrode pads for external wire connection occurs and makes the internal temperature maxima shift from the electrode plane to a bit of distance right above the cross-shaped interelectrode gaps, giving rise to reversal of flow rotation from a typical repulsion-type to attraction-type induction vortex, which is in good accordance with our experimental observations of co-field TWET streaming at frequencies on the order of reciprocal charge relaxation time of the bulk fluid. These results point out a way to make a correct interpretation of out-of-phase electrothermal streaming behavior, which holds great potential for handing high-conductivity analytes in modern microfluidic systems.

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UNDERSTANDING ELECTRIC INTERACTIONS IN SUSPENSIONS IN GRADIENT AC ELECTRIC FIELDS I: EXPERIMENTAL

International Journal of Modern Physics B ◽

10.1142/s0217979211058481 ◽

2011 ◽

Vol 25 (07) ◽

pp. 919-925

Author(s):

YAN SHEN ◽

ZHIYONG QIU ◽

SHIGERU TADA

Keyword(s):

Electric Field ◽

Electric Fields ◽

Corn Oil ◽

Electrode Array ◽

Ac Electric Fields ◽

Ac Electric Field ◽

Alpha Olefin ◽

Dilute Suspensions ◽

Spatially Periodic ◽

Neutrally Buoyant

When neutrally buoyant poly alpha olefin particles in corn oil were exposed to a gradient ac electric field generated by a spatially periodic electrode array, these particles experienced the negative dielectrophoresis and instability in all the suspensions of concentration range from 0.01% to 5% (v/v). One critical particle concentration was experimentally determined as 1% (v/v) below which the particles in corn oil were segregated to form island-like structures in the lower electric field regions; and above which, particles only formed straight stripes. The island-like structure was suspended in the lowest electric field area. Specially designed experiments with a suspension of 1.126% (v/v) confirmed that there exists particle instability. Anisotropic properties of electric interactions are responsible for particle instability in all the suspensions of different concentrations and island-like structures were formed only in the dilute suspensions in which the particle instability has enough space to be developed.

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Dynamic Control of Sliding Directions of Kinesin-Driven Microtubules With Rotating Electric Fields

ASME 2008 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2008-192496 ◽

2008 ◽

Author(s):

Shukei Sugita ◽

Naoya Sakamoto ◽

Toshiro Ohashi ◽

Masaaki Sato

Keyword(s):

Angular Velocity ◽

Electric Field ◽

Electric Fields ◽

Dynamic Control ◽

Rate Of Change ◽

Precise Control ◽

Biomolecular Motors ◽

Random Direction

Kinesins, biomolecular motors that move along microtubules (MTs) can potentially be utilized as an actuator in nanoscale transporting systems. Recent studies have reported inverted geometry in vitro, in which MTs randomly moved on kinesins fixed to substrates. To develop the transporting systems, one of key elements includes precise control of the direction of sliding MTs. One possible method is to utilize electric field (EF) to direct the MTs because MTs are negatively charged in neutral solutions [1,2]. For example, MTs have been shown to orient to the direction of uniaxially or biaxially applied EFs [3,4]. However, for a reliable transporting system, further studies are still required to control the direction of sliding MTs dynamically and effectively. In our previous study [5], we applied EF to MTs in random direction and showed that the rate of change in angle (angular velocity) was proportional to the sin of the angle between the directions of MTs and the generated electrophoretic force. The result indicates that it is most efficient to continuously apply EF perpendicular to the direction of MTs. In this study, the direction of sliding MTs was dynamically controlled with EF, particularly demonstrating a circular movement of MTs.

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Modelling and Fabrication of 3-D Carbon-MEMS for Dielectrophoretic Manipulation of Micro/Nanoparticles in Fluids

Materials Science Forum ◽

10.4028/www.scientific.net/msf.628-629.435 ◽

2009 ◽

Vol 628-629 ◽

pp. 435-440 ◽

Cited By ~ 1

Author(s):

Zi Rong Tang ◽

M.Rizwan Malik ◽

Tie Lin Shi ◽

J. Gong ◽

L. Nie ◽

...

Keyword(s):

Electric Field ◽

Electric Fields ◽

Cross Sections ◽

Microelectrode Array ◽

Three Dimensional ◽

Electrode Array ◽

Nano Particles ◽

Nano Technology ◽

Aspect Ratios ◽

Carbon Mems

Carbon-MEMS (C-MEMS) have emerged as a new category of devices for micro/nano technology with many potential applications. Dielectrophoretic manipulation of micro/nanoparticles with C-MEMS is studied in this paper. Through electric field distribution modeling in carbon electrode array, we analyze the strongest simulation effect results of electric field in three dimensional (3-D) surface plots depicting the magnitude of electric field in various cross sections at different heights above the channel floor for 2, 10, 30 and 50 μm high carbon electrodes. It is represented here that maximum intensity of electric field generates with the equality between the height above the channel floor and the height of the electrodes. Simulation parameters involved are for dielectrophoretic manipulation of micro/nano particles based on 3-D C-MEMS. The advantages of using 3-D C-MEMS electrodes over other techniques of creating high-throughput systems for dielectrophoretic manipulation environment surrounded by micro/nano horizons are: (i) complex microscale 3-D electrodes with high-aspect ratios can easily be shaped and patterned using conventional lithography (ii) carbon has a high window of stability thus allowing application of higher voltages (iii) there is no need for bulk micromachining or patterning electrodes on multiple planes (iv) the distance between electrodes can precisely be controlled through the lithography process. FEMLAB 3.4 Multiphysics Modeling software (COMSOL, Stockholm, Sweden) is used for the modeling of electric fields and one-layer C-MEMS microelectrode array was fabricated with SU-8 photoresist.

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Tuning the Electric Field Response of MOFs by Rotatable Dipolar Linkers

10.26434/chemrxiv.8153198.v1 ◽

2019 ◽

Author(s):

Johannes P. Dürholt ◽

Babak Farhadi Jahromi ◽

Rochus Schmid

Keyword(s):

Electric Field ◽

Electric Fields ◽

Structural Changes ◽

Dielectric Behavior ◽

Two Dimensions ◽

Dielectric Constants ◽

Electric Response ◽

Dipole Strength ◽

Metal Organic ◽

Dynamics Simulations

Recently the possibility of using electric fields as a further stimulus to trigger structural changes in metal-organic frameworks (MOFs) has been investigated. In general, rotatable groups or other types of mechanical motion can be driven by electric fields. In this study we demonstrate how the electric response of MOFs can be tuned by adding rotatable dipolar linkers, generating a material that exhibits paralectric behavior in two dimensions and dielectric behavior in one dimension. The suitability of four different methods to compute the relative permittivity κ by means of molecular dynamics simulations was validated. The dependency of the permittivity on temperature T and dipole strength μ was determined. It was found that the herein investigated systems exhibit a high degree of tunability and substantially larger dielectric constants as expected for MOFs in general. The temperature dependency of κ obeys the Curie-Weiss law. In addition, the influence of dipolar linkers on the electric field induced breathing behavior was investigated. With increasing dipole moment, lower field strength are required to trigger the contraction. These investigations set the stage for an application of such systems as dielectric sensors, order-disorder ferroelectrics or any scenario where movable dipolar fragments respond to external electric fields.

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Meta-Deflectors Made of Dielectric Nanohole Arrays with Anti-Damage Potential

Photonics ◽

10.3390/photonics8040107 ◽

2021 ◽

Vol 8 (4) ◽

pp. 107

Author(s):

Haichao Yu ◽

Feng Tang ◽

Jingjun Wu ◽

Zao Yi ◽

Xin Ye ◽

...

Keyword(s):

Electric Field ◽

Electric Fields ◽

Laser Cutting ◽

High Complexity ◽

Damage Potential ◽

Optical Components ◽

Nanohole Arrays ◽

Intense Light ◽

Polarization Of Light ◽

Air Hole

In intense-light systems, the traditional discrete optical components lead to high complexity and high cost. Metasurfaces, which have received increasing attention due to the ability to locally manipulate the amplitude, phase, and polarization of light, are promising for addressing this issue. In the study, a metasurface-based reflective deflector is investigated which is composed of silicon nanohole arrays that confine the strongest electric field in the air zone. Subsequently, the in-air electric field does not interact with the silicon material directly, attenuating the optothermal effect that causes laser damage. The highest reflectance of nanoholes can be above 99% while the strongest electric fields are tuned into the air zone. One presentative deflector is designed based on these nanoholes with in-air-hole field confinement and anti-damage potential. The 1st order of the meta-deflector has the highest reflectance of 55.74%, and the reflectance sum of all the orders of the meta-deflector is 92.38%. The optothermal simulations show that the meta-deflector can theoretically handle a maximum laser density of 0.24 W/µm2. The study provides an approach to improving the anti-damage property of the reflective phase-control metasurfaces for intense-light systems, which can be exploited in many applications, such as laser scalpels, laser cutting devices, etc.

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Integrating flexible electronics for pulsed electric field delivery in a vascularized 3D glioblastoma model

npj Flexible Electronics ◽

10.1038/s41528-021-00115-x ◽

2021 ◽

Vol 5 (1) ◽

Author(s):

Marie C. Lefevre ◽

Gerwin Dijk ◽

Attila Kaszas ◽

Martin Baca ◽

David Moreau ◽

...

Keyword(s):

Electric Field ◽

Electric Fields ◽

Flexible Electronics ◽

Soft Tissues ◽

Multiphoton Microscopy ◽

Membrane Integrity ◽

Tumor Model ◽

Pulsed Electric Fields ◽

In Ovo ◽

Cell Membrane Integrity

AbstractGlioblastoma is a highly aggressive brain tumor, very invasive and thus difficult to eradicate with standard oncology therapies. Bioelectric treatments based on pulsed electric fields have proven to be a successful method to treat cancerous tissues. However, they rely on stiff electrodes, which cause acute and chronic injuries, especially in soft tissues like the brain. Here we demonstrate the feasibility of delivering pulsed electric fields with flexible electronics using an in ovo vascularized tumor model. We show with fluorescence widefield and multiphoton microscopy that pulsed electric fields induce vasoconstriction of blood vessels and evoke calcium signals in vascularized glioblastoma spheroids stably expressing a genetically encoded fluorescence reporter. Simulations of the electric field delivery are compared with the measured influence of electric field effects on cell membrane integrity in exposed tumor cells. Our results confirm the feasibility of flexible electronics as a means of delivering intense pulsed electric fields to tumors in an intravital 3D vascularized model of human glioblastoma.

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Sensing Electrochemical Signals Using a Nitrogen-Vacancy Center in Diamond

Nanomaterials ◽

10.3390/nano11020358 ◽

2021 ◽

Vol 11 (2) ◽

pp. 358

Author(s):

Hossein T. Dinani ◽

Enrique Muñoz ◽

Jeronimo R. Maze

Keyword(s):

Electric Field ◽

Electron Spin ◽

Electrolyte Solution ◽

High Sensitivity ◽

Theoretical Work ◽

Coherence Time ◽

Nitrogen Vacancy ◽

Local Concentration ◽

Concentration Of Ions ◽

Nv Center

Chemical sensors with high sensitivity that can be used under extreme conditions and can be miniaturized are of high interest in science and industry. The nitrogen-vacancy (NV) center in diamond is an ideal candidate as a nanosensor due to the long coherence time of its electron spin and its optical accessibility. In this theoretical work, we propose the use of an NV center to detect electrochemical signals emerging from an electrolyte solution, thus obtaining a concentration sensor. For this purpose, we propose the use of the inhomogeneous dephasing rate of the electron spin of the NV center (1/T2★) as a signal. We show that for a range of mean ionic concentrations in the bulk of the electrolyte solution, the electric field fluctuations produced by the diffusional fluctuations in the local concentration of ions result in dephasing rates that can be inferred from free induction decay measurements. Moreover, we show that for a range of concentrations, the electric field generated at the position of the NV center can be used to estimate the concentration of ions.

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