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Alternating current electrokinetic properties of gold-coated microspheres

Alternating current electrokinetic properties of gold-coated microspheres
Alternating current electrokinetic properties of gold-coated microspheres
We present dielectrophoresis (DEP) and electrorotation (ROT) measurements of gold-coated polystyrene microspheres as a function of frequency and for several electrolyte conductivities. Particle rotation was counterfield with a maximum rotation rate observed at a single characteristic frequency. Negative DEP was observed for frequencies lower than this characteristic frequency and positive DEP for signal frequencies higher than this. These experimental observations are in agreement with predictions for the force and torque on the induced dipole of a perfectly polarizable metal sphere. We present a theoretical model for this case, and good agreement is found for both ROT and DEP measurements if we take into account the viscous friction for a spherical particle near a wall. From the characteristic frequency for rotation, we obtain the capacitance of the electrical double layer at the electrolyte–particle interface. Remarkably, no effect of induced charge electroosmosis around the particles can be inferred from DEP measurements.
0743-7463
13861-13870
García-Sánchez, Pablo
905183cb-9aa4-4e26-97b9-1917d762739d
Ren, Yukun
3273dba0-3e11-4743-8f29-b4e6df9217c6
Arcenegui, Juan J.
bfc61c9e-63af-41e6-9820-07e41521cf1a
Morgan, Hywel
de00d59f-a5a2-48c4-a99a-1d5dd7854174
Ramos, Antonio
511ab594-f312-45ce-b7ff-ef348fd9b559
García-Sánchez, Pablo
905183cb-9aa4-4e26-97b9-1917d762739d
Ren, Yukun
3273dba0-3e11-4743-8f29-b4e6df9217c6
Arcenegui, Juan J.
bfc61c9e-63af-41e6-9820-07e41521cf1a
Morgan, Hywel
de00d59f-a5a2-48c4-a99a-1d5dd7854174
Ramos, Antonio
511ab594-f312-45ce-b7ff-ef348fd9b559

García-Sánchez, Pablo, Ren, Yukun, Arcenegui, Juan J., Morgan, Hywel and Ramos, Antonio (2012) Alternating current electrokinetic properties of gold-coated microspheres. Langmuir, 28 (39), 13861-13870. (doi:10.1021/la302402v).

Record type: Article

Abstract

We present dielectrophoresis (DEP) and electrorotation (ROT) measurements of gold-coated polystyrene microspheres as a function of frequency and for several electrolyte conductivities. Particle rotation was counterfield with a maximum rotation rate observed at a single characteristic frequency. Negative DEP was observed for frequencies lower than this characteristic frequency and positive DEP for signal frequencies higher than this. These experimental observations are in agreement with predictions for the force and torque on the induced dipole of a perfectly polarizable metal sphere. We present a theoretical model for this case, and good agreement is found for both ROT and DEP measurements if we take into account the viscous friction for a spherical particle near a wall. From the characteristic frequency for rotation, we obtain the capacitance of the electrical double layer at the electrolyte–particle interface. Remarkably, no effect of induced charge electroosmosis around the particles can be inferred from DEP measurements.

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More information

Published date: 29 August 2012
Organisations: Electronics & Computer Science

Identifiers

Local EPrints ID: 354468
URI: https://eprints.soton.ac.uk/id/eprint/354468
ISSN: 0743-7463
PURE UUID: 3e4fb61f-1429-4553-969c-96ba1812f003
ORCID for Hywel Morgan: ORCID iD orcid.org/0000-0003-4850-5676

Catalogue record

Date deposited: 15 Jul 2013 12:29
Last modified: 10 Sep 2019 00:45

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