Dielectrophoresis of nanoparticles

Kadaksham, A.; Singh, Pushpendra; Aubry, Nadine

doi:10.1002/elps.200406092

Cited by 101 publications

(73 citation statements)

References 17 publications

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“…Similarly, the electrostatic interactions among polarized particles, which normally cause the particles to cluster in the direction of the electric field when particles are suspended in a bulk fluid (mutual attraction leading to chain formation), create here repulsive forces instead, thus preventing the particles from clustering. To further explain this, we note that when the line joining the centers of two particles is perpendicular to the electric field, the force acting on them is repulsive and when it is parallel the force is attractive (16)(17)(18)(19)(20)(21)(22)(23). The former orientation, however, is typically unstable, and therefore, particles of an electrorheological suspension cluster into chains aligned with the electric field direction.…”

Section: Resultsmentioning

confidence: 99%

“…However, the repulsive forces caused by the interparticles electrostatic interactions (Eq. 2) decay relatively faster (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23) with the distance between the particles (these forces decay as r Ϫ4 ). Because the repulsive force decays faster than the attractive capillary force, there is an equilibrium distance at which the two curves intersect and the total lateral force acting on the particles is zero.…”

Section: Resultsmentioning

confidence: 99%

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Micro- and nanoparticles self-assembly for virtually defect-free, adjustable monolayers

Aubry

Singh

Janjua

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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As chips further shrink toward smaller scales, fabrication processes based on the self-assembly of individual particles into patterns or structures are often sought. One of the most popular techniques for two-dimensional assembly (self-assembled monolayers) is based on capillary forces acting on particles placed at a liquid interface. Capillarity-induced clustering, however, has several limitations: it applies to relatively large (radius > Ϸ10 m) particles only, the clustering is usually non-defect-free and lacks long-range order, and the lattice spacing cannot be adjusted. The goal of the present article is to show that these shortcomings can be addressed by using an external electric field normal to the interface. The resulting self-assembly is capable of controlling the lattice spacing statically or dynamically, forming virtually defect-free monolayers, and manipulating a broad range of particle sizes and types including nanoparticles and electrically neutral particles.nterparticle force-driven self-assembly processes are often used to form materials with desired micro-and nanostructures (1, 2). In these processes, the forces, such as intermolecular or capillary forces, bring the particles together and cause them to arrange locally according to a pattern that depends on the orientational nature of these forces (1-5). Many envisioned applications of nanotechnology and fabrication of mesoscopic objects strongly rely on the manufacturing of such micro-and nanostructured materials (6-8). Future progress in this area will critically depend on our ability to accurately control the particle arrangement (e.g., lattice spacing, defect-free capability, and long-range order) in three dimensions (3D) and in two dimensions (2D) for a broad range of particle sizes, shapes, and types. Such a control in 2D will lead to the manufacture of controlled monolayers or ultrafine porous membranes with adjustable, but regular, pore sizes, and therefore with adaptable mechanical, thermal, electrical, and/or optical properties (e.g., controlled nanofluidic drug delivery patches with adjustable mass transfer properties across the patch, nanofilters for protein separation based on their sizes, electronic nanocircuits with improved performance in absence of defects, photonic devices, etc.).A popular mean used to assemble particles is based on the phenomenon of capillarity (3-5, 9-15). A common example of capillarity-driven self-assembly is the clustering of cereal flakes floating on the surface of milk. The floating cereal particles experience attractive capillary forces, because when two such particles are close to each other, the deformed interface around them is not symmetric because the interface height between the particles is lowered owing to the interfacial tension (9-15). This lowering of the interface between the particles gives rise to lateral forces that cause them to come together. Capillarityinduced clustering has several deficiencies: (i) the resulting particle structure is usually not defect-free: defects take place because...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Micro- and nanoparticles self-assembly for virtually defect-free, adjustable monolayers

Aubry

Singh

Janjua

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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“…Using this expression, it is easy to show that the electrostatic interaction force between two particles is attractive and also that it causes the particles to orient such that the line joining their centers is parallel to the electric field direction (except in the degenerate case when the line joining their centers is perpendicular to the electric field, in which case they repel). Similar interactions take place between particles in a nonuniform electric field [27,30,31]. Direct numerical simulations (DNS) conducted using this expression for the interaction force show that two particles subjected to a nonuniform electric field attract each other and orient such that the line joining their centers is parallel to the local electric field direction while they move together toward the location where the electric field strength is locally maximal or minimal, depending on the value of their dielectric constant relative to that of the two fluids [32][33][34].…”

Section: Dep Forces On Particlesmentioning

confidence: 98%

Concentrating particles on drop surfaces using external electric fields

et al. 2008

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We propose to use an externally applied uniform electric field to alter the distribution of particles on the surface of a drop immersed in another immiscible liquid. Specifically, we seek to generate well-defined concentrated regions at the drop surface while leaving the rest of the surface particle free. Experiments show that when the dielectric constant of the drop is greater than that of the ambient liquid the particles for which the Clausius-Mossotti factor is positive move along the drop surface to the two poles of the drop. Particles with a negative Clausius-Mossotti factor, on the other hand, move along the drop surface to form a ring near the drop equator. The opposite takes place when the dielectric constant of the drop is smaller than that of the ambient liquid, namely particles for which the Clausius-Mossotti factor is positive form a ring near the equator while those for which such a factor is negative move to the poles. This motion is due to the dielectrophoretic force that acts upon particles because the electric field on the surface of the drop is nonuniform, despite the uniformity of the applied electric field. Experiments also show that when small particles collect at the poles of a deformed drop the electric field needed to break the drop is smaller than without particles. These phenomena could be useful to concentrate particles at a drop surface within well-defined regions (poles and equator), separate two types of particles at the surface of a drop or increase the drop deformation to accelerate drop breakup.

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“…(10), (15), and (16)) offer a clear indication of the competing role of the particle dielectric constants and the surrounding medium. In particular, if they are equal the DEP forces extinguish.…”

Section: Dep Forcesmentioning

confidence: 99%

“…[11][12][13][14] This strategy can be easily integrated in lab-on-chip devices. 15 Following this strategy, domain structuring of ferroelectric surfaces [16][17][18] allows the use of the associated electrostatic fields and/or suitable electrochemical reactions for manipulation and patterning of molecules and nanoparticles. [19][20][21] Pyroelectric fields in domain structured ferroelectric surfaces have been also proposed to induce the dielectrophoretic (DEP) forces required for nanoparticle patterning.…”

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confidence: 99%

LiNbO3: A photovoltaic substrate for massive parallel manipulation and patterning of nano-objects

Carrascosa

Garcı́a-Cabañes

Jubera

et al. 2015

Applied Physics Reviews

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The application of evanescent photovoltaic (PV) fields, generated by visible illumination of Fe:LiNbO 3 substrates, for parallel massive trapping and manipulation of micro-and nano-objects is critically reviewed. The technique has been often referred to as photovoltaic or photorefractive tweezers. The main advantage of the new method is that the involved electrophoretic and/or dielectrophoretic forces do not require any electrodes and large scale manipulation of nano-objects can be easily achieved using the patterning capabilities of light. The paper describes the experimental techniques for particle trapping and the main reported experimental results obtained with a variety of micro-and nano-particles (dielectric and conductive) and different illumination configurations (single beam, holographic geometry, and spatial light modulator projection). The report also pays attention to the physical basis of the method, namely, the coupling of the evanescent photorefractive fields to the dielectric response of the nano-particles. The role of a number of physical parameters such as the contrast and spatial periodicities of the illumination pattern or the particle deposition method is discussed. Moreover, the main properties of the obtained particle patterns in relation to potential applications are summarized, and first demonstrations reviewed. Finally, the PV method is discussed in comparison to other patterning strategies, such as those based on the pyroelectric response and the electric fields associated to domain poling of ferroelectric materials.

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Dielectrophoresis of nanoparticles

Cited by 101 publications

References 17 publications

Micro- and nanoparticles self-assembly for virtually defect-free, adjustable monolayers

Micro- and nanoparticles self-assembly for virtually defect-free, adjustable monolayers

Concentrating particles on drop surfaces using external electric fields

LiNbO3: A photovoltaic substrate for massive parallel manipulation and patterning of nano-objects

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