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Ac electrokinetics: a review of forces in microelectrode structures

Ac electrokinetics: a review of forces in microelectrode structures
Ac electrokinetics: a review of forces in microelectrode structures
Ac electrokinetics is concerned with the study of the movement and behaviour of particles in suspension when they are subjected to ac electrical fields. The development of new microfabricated electrode structures has meant that particles down to the size of macromolecules have been manipulated, but on this scale forces other than electrokinetic affect particles behaviour. The high electrical fields, which are required to produce sufficient force to move a particle, result in heat dissipation in the medium. This in turn produces thermal gradients, which may give rise to fluid motion through buoyancy, and electrothermal forces. In this paper, the frequency dependency and magnitude of electrothermally induced fluid flow are discussed. A new type of fluid flow is identified for low frequencies (up to 500 kHz). Our preliminary observations indicate that it has its origin in the action of a tangential electrical field on the diffuse double layer of the microfabricated electrodes. The effects of Brownian motion, diffusion and the buoyancy force are discussed in the context of the controlled manipulation of sub-micrometre particles. The orders of magnitude of the various forces experienced by a sub-micrometre latex particle in a model electrode structure are calculated. The results are compared with experiment and the relative influence of each type of force on the overall behaviour of particles is described.
0022-3727
2338
Ramos, Antonio
511ab594-f312-45ce-b7ff-ef348fd9b559
Morgan, Hywel
de00d59f-a5a2-48c4-a99a-1d5dd7854174
Green, Nicolas G
d9b47269-c426-41fd-a41d-5f4579faa581
castellanos, Antonio
aa989a75-63b0-4f3e-a36b-370545034d7b
Ramos, Antonio
511ab594-f312-45ce-b7ff-ef348fd9b559
Morgan, Hywel
de00d59f-a5a2-48c4-a99a-1d5dd7854174
Green, Nicolas G
d9b47269-c426-41fd-a41d-5f4579faa581
castellanos, Antonio
aa989a75-63b0-4f3e-a36b-370545034d7b

Ramos, Antonio, Morgan, Hywel, Green, Nicolas G and castellanos, Antonio (1998) Ac electrokinetics: a review of forces in microelectrode structures. Journal of Physics D: Applied Physics, 31, 2338. (doi:10.1088/0022-3727/31/18/021).

Record type: Article

Abstract

Ac electrokinetics is concerned with the study of the movement and behaviour of particles in suspension when they are subjected to ac electrical fields. The development of new microfabricated electrode structures has meant that particles down to the size of macromolecules have been manipulated, but on this scale forces other than electrokinetic affect particles behaviour. The high electrical fields, which are required to produce sufficient force to move a particle, result in heat dissipation in the medium. This in turn produces thermal gradients, which may give rise to fluid motion through buoyancy, and electrothermal forces. In this paper, the frequency dependency and magnitude of electrothermally induced fluid flow are discussed. A new type of fluid flow is identified for low frequencies (up to 500 kHz). Our preliminary observations indicate that it has its origin in the action of a tangential electrical field on the diffuse double layer of the microfabricated electrodes. The effects of Brownian motion, diffusion and the buoyancy force are discussed in the context of the controlled manipulation of sub-micrometre particles. The orders of magnitude of the various forces experienced by a sub-micrometre latex particle in a model electrode structure are calculated. The results are compared with experiment and the relative influence of each type of force on the overall behaviour of particles is described.

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J7_Ramos_Morgan_Green_Castellanos_J_Physics_D_Applied_Physics_1998.pdf - Other
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Published date: 1998
Organisations: Electronics & Computer Science

Identifiers

Local EPrints ID: 372368
URI: https://eprints.soton.ac.uk/id/eprint/372368
ISSN: 0022-3727
PURE UUID: 8a59ca66-80fe-4011-a6ee-0548e13f99fd
ORCID for Hywel Morgan: ORCID iD orcid.org/0000-0003-4850-5676
ORCID for Nicolas G Green: ORCID iD orcid.org/0000-0001-9230-4455

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Date deposited: 01 Dec 2014 17:18
Last modified: 10 Sep 2019 00:45

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Contributors

Author: Antonio Ramos
Author: Hywel Morgan ORCID iD
Author: Nicolas G Green ORCID iD
Author: Antonio castellanos

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