AC electrokinetics: applications for nanotechnology

Hughes, Michael

doi:10.1088/0957-4484/11/2/314

Cited by 266 publications

(180 citation statements)

References 53 publications

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“…The torque causes an alignment of the induced dipole along the electric field lines. 3 The behavior of charged polymeric molecules such as DNA when pulled by external forces, for example in an electric field, can be described by the wormlike chain (WLC) model. 30 The WLC model is a special limit of the KratkyPorod (KP) model, 31 where the molecule is approximated as a succession of N segments of length b.…”

Section: A Frequency and Amplitude Dependence Of Dna Elongationmentioning

confidence: 99%

“…The reorientation of the charges along the backbone of the DNA starts lagging behind the switch in the polarity of the electrodes in the ac field with increasing frequencies, leading to a decrease of the effective dipole moment and thus torque. 3,24 Figure 5(a) shows the normalized length L n = L / L 0 , where L is the measured length and L 0 the contour length, of the four elongated DNA fragments as a function of frequency at an electric field of 0.5 MV/ m across a 40 m gap. As also shown before, all the different fragments were fully elongated at frequencies of 200-300 kHz.…”

Section: A Frequency and Amplitude Dependence Of Dna Elongationmentioning

confidence: 99%

“…In the molecule itself, a dipole is induced as a result of the redistribution of charges at the molecule-electrolyte interface, 1 which, in a nonuniform field, leads to a dielectrophoretic force on the molecule. In addition, a torque, which aligns the dipole with the electric field, [1][2][3][4] is exerted on the molecule. This phenomenon is known as electro-orientation.…”

Section: Introductionmentioning

confidence: 99%

“…3 The applied ac electric field can also lead to fluid flow, which in turn can result in movement of the molecule. 3,5,6 The manipulation of small particles using dielectrophoresis and ac electrokinetic techniques in general has recently received considerable attention as an alternative to optical tweezers 7,8 or scanning probe techniques, 9,10 and is becoming a useful tool in molecular biology and biotechnology. Dielectrophoretic forces have been used to separate and manipulate cells, 2,11 bacteria, 12,13 viruses, 14 and submicron latex spheres.…”

Section: Introductionmentioning

confidence: 99%

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Influence of alternating current electrokinetic forces and torque on the elongation of immobilized DNA

Germishuizen

Tosch

Middelberg

et al. 2004

Journal of Applied Physics

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Articles you may be interested inThe authors investigate the elongation and orientation of different-sized deoxyribose nucleic acid (DNA) molecules, tethered onto gold electrodes via a terminal thiol, under the influence of high frequency ac electric fields. The DNA molecules are elongated from a random coil into an extended conformation and orientated along the electric field lines as a result of the forces acting on the molecules during the application of the ac electric fields. Elongation was observed in the frequency range 100 kHz-1 MHz, with field strengths of 0.06-1.0 MV/ m. Maximum elongation for all DNA fragments tested, irrespective of size, was found for frequencies between 200 and 300 kHz. The torque acting on the induced dipole in the DNA molecules, complemented by a directional bias force, opposite in direction to the dielectrophoretic force, provides the main contribution to the elongation process. The length of elongation is limited to either half the distance between opposing electrodes or to the contour length of the DNA, whichever is shorter. Further, the authors show that the normalized length of the elongated DNA molecules is independent of the contour length of the DNA.

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Section: A Frequency and Amplitude Dependence Of Dna Elongationmentioning

confidence: 99%

Section: A Frequency and Amplitude Dependence Of Dna Elongationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of alternating current electrokinetic forces and torque on the elongation of immobilized DNA

Germishuizen

Tosch

Middelberg

et al. 2004

Journal of Applied Physics

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“…The phase sequence addressing employed has been described by many investigators. 5,7,3,4,1,8 The two parallel electrode arrays offer advantages for cell manipulation and positioning. The methods allow cells to move either toward the electrode tips or along the electrode track simultaneously as a result of two orthogonal forces.…”

Section: Introductionmentioning

confidence: 99%

Dielectrophoretic spectra of translational velocity and critical frequency for a spheroid in traveling electric field

et al. 2010

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An analysis has been made of the dielectrophoretic ͑DEP͒ forces acting on a spheroidal particle in a traveling alternating electric field. The traveling field can be generated by application of alternating current signals to an octapair electrode array arranged in phase quadrature sequence. The frequency dependent force can be resolved into two orthogonal forces that are determined by the real and the imaginary parts of the Clausius-Mossotti factor. The former is determined by the gradient in the electric field and directs the particle either toward or away from the tip of the electrodes in the electrode array. The force determined by the imaginary component is in a direction along the track of the octapair interdigitated electrode array. The DEP forces are related to the dielectric properties of the particle. Experiments were conducted to determine the DEP forces in such an electrode arrangement using yeast cells ͑Saccharomyces cervisiate TISTR 5088͒ with media of various conductivities. Experimental data are presented for both viable and nonviable cells. The dielectric properties so obtained were similar to those previously reported in literature using other DEP techniques.

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Coupled Electrorotation: Two Proximate Microspheres Spin in Registry with an AC Electric Field

Simpson¹,

Wilson²,

Gericke³

et al. 2002

ChemPhysChem

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We report a novel approach to micro‐ and nanoparticle rotation, uniting the fine translational control afforded by optical trapping with the flexibility and simplicity of dipole–field‐induced coupled electrorotation (CER). Fluorescence imaging using a microparticle photopatterning technique was combined with optical trapping to quantify both the senses and speeds of rotation for individual pairs of particles. Laser tweezers allowed controlled positioning of a pair of particles within a dipole field while simultaneously providing an axis about which the particles rotated. The particle–particle interactions inherent in CER offer several distinct advantages compared with electrorotation in multipole fields. Results from several investigations highlight the utility of this approach, including quantification of rotation in spheres as small as 750 nm in diameter, observation of rotation rates as high as 1800 rpm, fabrication of coupled electrorotational ”antigears”, trapping and rotation of sphere dimers, and exploitation of the registry of sphere rotation to probe the dielectric properties of immobile objects.

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AC electrokinetics: applications for nanotechnology

Cited by 266 publications

References 53 publications

Influence of alternating current electrokinetic forces and torque on the elongation of immobilized DNA

Influence of alternating current electrokinetic forces and torque on the elongation of immobilized DNA

Dielectrophoretic spectra of translational velocity and critical frequency for a spheroid in traveling electric field

Coupled Electrorotation: Two Proximate Microspheres Spin in Registry with an AC Electric Field

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