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Numerical simulation of travelling wave induced electrothermal fluid flow

Numerical simulation of travelling wave induced electrothermal fluid flow
Numerical simulation of travelling wave induced electrothermal fluid flow
Many microdevices for manipulating particles and cells use electric fields to produce a motive force on the particles. The movement of particles in non-uniform electric fields is called dielectrophoresis, and the usual method of applying this effect is to pass the particle suspension over a microelectrode structure. If the suspension has a noticeable conductivity, one important side effect is that the electric field drives a substantial conduction current through the fluid, causing localized Joule-heating. The resulting thermal gradient produces local conductivity and permittivity changes in the fluid. dielectrophoretic forces acting upon these pockets of fluid will then produce motion of both the fluid and the particles. This paper presents a numerical solution of the electrical force and the resulting electrothermal driven fluid flow on a travelling wave structure. This common electrode geometry consists of interdigitated electrodes laid down in a long array, with the phase of the applied potential shifted by 90° on each subsequent electrode. The resulting travelling electric field was simulated and the thermal field and electrical body force on the fluid calculated, for devices constructed from two typical materials: silicon and glass. The electrothermal fluid flow in the electrolyte over the electrode array was then numerically simulated. The model predicts that the thermal field depends on the conductivity and applied voltage, but more importantly on the geometry of the system and the material used in the construction of the device. The velocity of the fluid flow depends critically on the same parameters, with slight differences in the thermal field for glass and silicon leading to diametrically opposite flow direction with respect to the travelling field for the two materials. In addition, the imposition of slight external temperature gradients is shown to have a large effect on the fluid flow in the device, under certain conditions leading to a reversal of the fluid flow direction.
0022-3727
2323-2330
Perch-Nielsen, Ivan R
046b4347-5d6d-4da1-8889-d48ff07c9498
Green, Nicolas G
d9b47269-c426-41fd-a41d-5f4579faa581
Wolff, Anders
925149b2-6e62-4883-8aa8-8b48484c2e08
Perch-Nielsen, Ivan R
046b4347-5d6d-4da1-8889-d48ff07c9498
Green, Nicolas G
d9b47269-c426-41fd-a41d-5f4579faa581
Wolff, Anders
925149b2-6e62-4883-8aa8-8b48484c2e08

Perch-Nielsen, Ivan R, Green, Nicolas G and Wolff, Anders (2004) Numerical simulation of travelling wave induced electrothermal fluid flow. Journal of Physics D: Applied Physics, 37, 2323-2330. (doi:10.1088/0022-3727/37/16/016).

Record type: Article

Abstract

Many microdevices for manipulating particles and cells use electric fields to produce a motive force on the particles. The movement of particles in non-uniform electric fields is called dielectrophoresis, and the usual method of applying this effect is to pass the particle suspension over a microelectrode structure. If the suspension has a noticeable conductivity, one important side effect is that the electric field drives a substantial conduction current through the fluid, causing localized Joule-heating. The resulting thermal gradient produces local conductivity and permittivity changes in the fluid. dielectrophoretic forces acting upon these pockets of fluid will then produce motion of both the fluid and the particles. This paper presents a numerical solution of the electrical force and the resulting electrothermal driven fluid flow on a travelling wave structure. This common electrode geometry consists of interdigitated electrodes laid down in a long array, with the phase of the applied potential shifted by 90° on each subsequent electrode. The resulting travelling electric field was simulated and the thermal field and electrical body force on the fluid calculated, for devices constructed from two typical materials: silicon and glass. The electrothermal fluid flow in the electrolyte over the electrode array was then numerically simulated. The model predicts that the thermal field depends on the conductivity and applied voltage, but more importantly on the geometry of the system and the material used in the construction of the device. The velocity of the fluid flow depends critically on the same parameters, with slight differences in the thermal field for glass and silicon leading to diametrically opposite flow direction with respect to the travelling field for the two materials. In addition, the imposition of slight external temperature gradients is shown to have a large effect on the fluid flow in the device, under certain conditions leading to a reversal of the fluid flow direction.

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Published date: 2004
Organisations: Electronics & Computer Science

Identifiers

Local EPrints ID: 259836
URI: http://eprints.soton.ac.uk/id/eprint/259836
ISSN: 0022-3727
PURE UUID: 92db6666-25d7-4547-8ff9-5c82992fc018
ORCID for Nicolas G Green: ORCID iD orcid.org/0000-0001-9230-4455

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Date deposited: 25 Aug 2004
Last modified: 15 Mar 2024 03:20

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Contributors

Author: Ivan R Perch-Nielsen
Author: Nicolas G Green ORCID iD
Author: Anders Wolff

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