C m factor, and therefore on the permittivity and conductivity of both the carbon nanotube particles and the suspending medium, as well as the frequency of the applied electric field. Colloids and nanoparticles, research studies press, baldock, uk 2003 3 lyklema j. A theoretical study is provided for determining the angular rotation rate of an ideally polarized metallic spheroidal particle freely suspended in a symmetric electrolyte under general alternating current ambient electric excitations. Electrostatic stabilization of charged colloidal particles. Modeling the ac electrokinetic behavior of semiconducting. Huang y, wang xb, tame j and pethig r 1993 electrokinetic behaviour of colloidal particles in travelling electric. Manipulation of micro and nano particles with electric fields is a topic of research with applications in diverse fields such as biotechnology and microelectronics 1,2. Center for advanced processing green materials, yamagata university. Fluid properties at nano meso scale dyson et al september 2008 introduction to microsystem technology gerlach march 2008 ac electrokinetics. Electrohydrodynamics and dielectrophoresis in microsystems. The homework is due at the beginning of the thursday lecture of the next week. Ac electrokinetics of nanoparticles refers to methods of exerting electrical force and or torque on particles of nanometer dimensions, examples of which are viruses, macromolecules, and. Colloids and nanoparticles, baldock, hertfordshire.
The theoretical problems of electrokinetics at large induced voltages will be exposed. Modeling the ac electrokinetic behavior of semiconducting spheres. This paper describes the analytical and numerical modeling methods for eis of single cell analysis in a microfluidic cytometer. An ac electric field is applied to induce particle and fluid motion in a wedgeshaped microchannel. Remotely powered selfpropelling particles and micropumps. Colloidal particles near an electrode surface aloke kumar, jaesung kwon, stuart j. Supporting information physiological media based on. As a child, you may have made suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water, known as tempera paint. However, these advantages come with the added complexity of particle manipulation in a microscale environment. By performing desired analysis in picoliter to nanoliter volumes at high throughput, microfluidic devices outperform some of the conventional benchtop technologies. A castellanos, a ramos, a gonzalez, ng green, h morgan. The ac electrokinetic behavior of conducting particles turns to. The authors show how electrokinetic phenomena can be employed to manipulate and characterise particles within such microsystems. Simulations of the electric field gradient variation using various ratios of the semimajor and the semiminor axis were carried out to determine the optimum elliptic geometry for the dielectrophoretic electrokinetics of specimen in an assay with laminar low reynolds number fluid flow.
Implication of hybrid electrokinetics in nanoparticles manipulation previously. Ac electrophoretic mobility of individual microscale colloidal particles measured using holographic video microscopy appl. Analysis of parasites by electrorotation dalton 2004. Signal outputs are frequently limited by diffusion 12. Colloids and nanoparticles microtechnologies and microsystems series 2 philadelphia, pa. The dependence of these quantities is very similar for bare charged latex particles and the same particles in the presence of the different oppositely charged polyelectrolytes. The method differs from other focusing methods in that it manipulates the particles and not the fluid. Optoelectrical microfluidics as a promising tool in. Colloids and nanoparticles morgan and green, january 2003 micro. In terms of labonachip loc technology, cells pass sequentially through the microfluidic channel at high speed and are analyzed individually, rather than as traditionally done on a mixture of particles in suspension. This force does not require the particle to be charged.
Introduction the need and ability to manipulate and assemble colloidal micro and nanoparticles is highly relevant for a broad range of microengineeringapplications. Ac dielectrophoresis using elliptic electrode geometry. The use of ac electric fields for manipulating and characterising small particles in suspension is wellknown 1, 2 and many applications have appeared over the last decades in fields such as colloidal science and biotechnology. A stable colloidal system is one in which the particles resist flocculation or aggregation and exhibits a long shelflife. Sorry, our data provider has not provided any external links therefor we are unable to provide a pdf. Further, conductivity differences between the particle and the medium may cause charges to build up on the interface morgan and green, 2001. Depends upon the balance of the repulsive and attractive forces that exist between particles as they approach one another. Green n g and morgan h 1997 dielectrophoretic separation of nanoparticles j. Morgan h, green n g and castellanos a 1999 ac electricfield induced fluid flow in microelectrodes j. Uniquely, under the application of a uniform ac electric field, metallodielectric janus particles where one hemisphere is conducting and the other dielectric respond as active colloids 10,11. Another electrokinetic technique, called dielectrophoresis dep, uses alternating current ac electric fields and can also be used for sample focussing. An ac electrokinetics facilitated biosensor cassette for rapid pathogen identi. Review of the theory of generalised dielectrophoresis.
In biological studies, these particles have included proteins, viruses, bacteria, cells and micro. Morgan, dielectrophoretic separation of nano particles. Microraman spectroscopy was found to be a suitable technique for detecting. May 20, 20 ac electrokinetics is becoming a strategic tool for labonachip systems due to its versatility and its high level of integration.
Micronresolution particle image velocimetry piv is used to determine spatially resolved. Sin,ab mason mccomb,e janhvi joshi,e vincent gau,e pak kin wongd and joseph c. As shown in the work of okonski 25, the conductivity of a solid homogeneous spherical particle such as a latex sphere is given by the sum of the bulk conductivity, and a surface conductivity given by 3 where is a general surface conductance typically 1 ns for latex particles, and a the particle radius. An ac electrokinetic technique for collection and concentration of particles and cells on patterned electrodes ketan h. Hywel morgan university of southampton, uk 5 lectures on. The direction and magnitude of the induced motion depend on the polarity and amount of net electrical charge of the particle, respectively 28,52. Ohta 1, peiyu chiou 1, hsanyin hsu 1, peidong yang 2,3 and ming c. Assembly of ordered colloidal aggregates by electricfieldinduced fluid flow.
Electrophoresis ep is defined as the motion of a charged particle relative to a stationary fluid, driven by an external electric field 28,52,53, 72. In ac electrokinetics, the application of an ac electric field to a. Continuousflow trapping and localized enrichment of micro and nano particles using inducedcharge electrokinetics. Comprehensive analysis of alternating current electrokinetics. Pumping of liquids with traveling wave electroosmosis. Electrophoretic rotation and orientation of polarizable. A castellanos 1, a ramos 1, a gonzalez 1,2, n g green 3 and h morgan 3,4. These suspensions are heterogeneous mixtures composed of relatively large particles that are visible or that can be seen with a magnifying glass. Dielectrophoresis assembling cancer cells in a 3d microfluidic model. Dielectrophoretic separation of particles is achieved by the generation of electric forces on the particles by nonuniform electric fields. The ability to foreseen the behaviour of fluids and particles under nonuniform ac electric fields is important to allow new generations of devices. This is due to a sifting mechanism in which tiny grains. Li m, qu y, dong z, wang y, li wj 2008 limitations of au particle nanoassembly using dielectrophoretic force. Morgan, hywel, green, nicolas and sun, tao 2008 electrokinetics of particles and fluids.
Read ac elektrokinetics colloids and nanoparticles now. Molecular driving forces, by ken dill and sarina bromberg, garland science. Biddiss e, erickson d, li d 2004 heterogeneous surface charge enhanced micromixing for electrokinetic flows. Research studies press 19 chiou p y, ohta a t and wu m c 2005 massively parallel manipulation of single cells and microparticles using optical images nature 436 3702. Jun mizuno received his phd in applied physics from tohoku university miyagi, japan in.
Optically modulated rapid electrokinetic patterning for. Bibliography includes bibliographical references and index. Electrode polarisation, dielectrophoresis and electrorotation. This paper describes a method for focusing nanoparticles using dielectrophoresis. Semiconductor nanowire manipulation using optoelectronic tweezers arash jamshidi 1, peter j. Remotely powered selfpropelling particles and micropumps based on miniature diodes. More recently, the manipulation of metal and semiconducting particles has been explored in the context of microfluidics and nanoelectronics. Colloids and nanoparticles microtechnologies and microsystems morgan, hywel, green, nicolas g. Nov 29, 2016 ac electrokinetics is the name given to a group of techniques that utilize alternating ac electric fields to move dielectric particles in suspension.
Efficient mixing is needed to optimize overall signaltonoise ratio snr of the biosensor and reproducibility of the results. Request pdf on jan 1, 2003, hywel morgan and others published ac electrokinetics. Though most of studies predicted motion of particles in coplanar electrodes configurations, we explore a pure 3d. Optically induced electrokinetic concentration and sorting of. Microsensors and micromachines that are capable of selfpropulsion through fluids could revolutionize many aspects of technology. Surface conductance and other properties of latex particles. Few principles to propel such devices and supply them with energy.
Pdf experimental analysis of particle and fluid motion in. Green nano research group, school of electronics and computer science, university of southampton, so17 1bj, united kingdom. After presenting the classical picture of electroosmosis and electrophoresis, we will examine the basic equations of induced charge electroosmosis, induced charge electrophoresis and ac electroosmosis. A ramosdag, h morganddag, n g greenddag and a castellanosdag. Electric field, dielectrophoretic and travelingwave dielectrophoretic forces. Ac electrokinetics is one of the most promising techniques to simplify sample preparation steps and improve sensor performance 14. Within a single channel, ac electrokinetics can accomplish many essential onchip operations such as active micromixing, particle separation, particle positioning and micropattering. The lectures will start with some basic concepts of electrical forces on particles including nano particles in suspension. Although using dc electric fields is important for the manipulation of nanoscale particles, high voltage operation and consequently excessive electrochemical reactions and electrolysis at the electrodes makes it less attractive in nano.
Dielectrophoresis is the movement of particles due to the interaction of a nonuniform electric field and the electrical dipole moment induced in the particle jones, 1995, morgan and green. Within a single channel, ac electrokinetics can accomplish many essential onchip operations such as active micromixing. Colloids and nanoparticles microtechnologies and microsystems. Ramos a, morgan h, green n g and castellanos a 1999 ac electric. Principles of colloid and surface chemistry, by hiemenz and rajagopalan, marcel dekker. Ac electrokinetics is the name given to a group of techniques that utilize alternating ac electric fields to move dielectric particles in suspension. Positively charged particles in the presence of anionic polyelectrolytes behave analogously to negatively charged particles in the presence of cationic polyelectrolytes. Wereley, birck nanotechnology center and school of mechanical engineering, purdue university, west lafayette. Active colloids as mobile microelectrodes for unified label. This paper presents negative ac dielectrophoretic investigations using elliptic electrode geometry. Ac electrokinetic manipulation of selenium nanoparticles for. In this book hywel morgan and nicolas green extend our understanding of the interaction of electric fields with particles and fluids in microsystems. Colloids and nanoparticles microtechnologies and microsystems microtechnologies and microsystems june 15, 2002, research studies press hardcover in english. They will then progress onto practical applications in microsystems and the lab on.
All particles exhibit dielectrophoretic activity in the presence of. Two types of electrokinetics are worth to consider, dc electric field application and ac electrokinetics. It, however, suffers from an intrinsic drawback of low throughput due to the linear dependence of the typically very low fluid permittivity. We describe a number of related phenomena, such as alternating current ac lcenabled electrophoresis of colloidal solid particles and fluid droplets in uniform and spatiallypatterned lcs, swarming of colloids guided by photoactivated surface patterns, control of lcek polarity through the material properties of the lc electrolyte, lcek. Analytical solutions of ac electrokinetics in interdigitated electrode arrays. Hybrid electrokinetics for separation, mixing, and concentration of colloidal particles. Microfluidics is ushering a new era in drug discovery 1, biological analysis, and pointofcare diagnostics 2,3. Ac electrokinetic phenomena generated by microelectrode. Recent experimental work has focused on conducting particles, and for example, semiconductor nanowires can be rotated and transported within microchannels with embedded. Manipulation of micro and nanoparticles with electric fields is a topic of research. The magnitude of the force depends on the dielectric properties of both the particle and the medium it is suspended in. Published 1 october 2003 2003 iop publishing ltd journal of physics d. Dynamic focusing of particles can be used to centre particles in a fluid stream, ensuring the passage of the particles through a specified detection volume. A nonuniform electric field exerts a force on a polarizable particle through the coulomb interaction with the electric dipole induced in the particle, resulting in a motion termed dielectrophoresis.
Ac electrokinetic phenomena use electric fields to generate forces that act on fluids or suspended particles including those made of dielectric or biological material and cause them to move in astonishing ways 1, 2. Ac electrokinetics of nanoparticles refers to methods of exerting electrical force andor torque on particles of nanometer dimensions, examples of which are viruses, macromolecules, and colloidal particles. Velev, department of chemical and biomolecular engineering, north carolina state university. Liaoab to develop a portable pointofcare system based on biosensors for common infectious diseases such as. On surface conduction and its role in electrokinetics. As a result, measurement of the dielectrophoretic force provides information. Jan 08, 2015 ac particle electrokinetics was shown to accelerate the focusing and capture of submicrometer sized bioparticles in antibodydecorated planar microelectrode arrays within only 20 s for the case of neutravidin particles 200 nm and 30 min for the case of m phage. Dynamic ellipsoidal model of polarization dispersion for colloids. A single device may accomplish several of those operations by simply adjusting operating parameters such as frequency or amplitude of the applied voltage. Ac electrokinetics alternating current ac electrokinetic techniques employ microelectrode structures to apply nonuniform, rotational or travelling ac electric fields to suspended particles. This is a pdf file of an unedited manuscript that has been accepted for publication. Che 596652 colloid science and nanoscale engineering. Electrokinetic manipulation refers to the control of particle and cell motions using an electric field.
Hybrid electrokinetics for separation, mixing, and. Optically modulated electrokinetic manipulation and. Design and generation of dielectrophoretic forces for. It is an efficient technique for microfluidic applications with the ease of operation and integration. In particular, we discuss cases of electrorotation rot and electroorientation eor of such nano micro particles incited by two orthogonal electric field. The class will include 4 discussion sections on recent trends and developments in colloids and nanoscience. Selfrotation of cells in an irrotational ac efield in an. Colloids and nanoparticles microtechnologies and microsystems microtechnologies and microsystems june 15, 2002, research studies press hardcover in english 1st edition. Green, ac electrokinetics colloids and nanoparticles research studies pressinstitute of physics publication. The authors show how electrokinetic phenomena can be employed to manipulate and characterise particles. Dielectrophoresis dep is a phenomenon in which a force is exerted on a dielectric particle when it is subjected to a nonuniform electric field.
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