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Dual-cycle dielectrophoretic collection rates for probing the dielectric properties of nanoparticles

Bakewell, DJ; Holmes, D; (2013) Dual-cycle dielectrophoretic collection rates for probing the dielectric properties of nanoparticles. Electrophoresis , 34 (7) 987 - 999. 10.1002/elps.201200422. Green open access

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Abstract

A new DEP spectroscopy method and supporting theoretical model is developed to systematically quantify the dielectric properties of nanoparticles using continuously pulsed DEP collection rates. Initial DEP collection rates, that are dependent on the nanoparticle dielectric properties, are an attractive alternative to the crossover frequency method for determining dielectric properties. The new method introduces dual-cycle amplitude modulated and frequency-switched DEP (dual-cycle DEP) where the first collection rate with a fixed frequency acts as a control, and the second collection rate frequency is switched to a chosen value, such that, it can effectively probe the dielectric properties of the nanoparticles. The application of the control means that measurement variation between DEP collection experiments is reduced so that the frequency-switched probe collection is more effective. A mathematical model of the dual-cycle method is developed that simulates the temporal dynamics of the dual-cycle DEP nanoparticle collection system. A new statistical method is also developed that enables systematic bivariate fitting of the multifrequency DEP collection rates to the Clausius–Mossotti function, and is instrumental for determining dielectric properties. A Monte-Carlo simulation validates that collection rates improve estimation of the dielectric properties, compared with the crossover method, by exploiting a larger number of independent samples. Experiments using 200 nm diameter latex nanospheres suspended in 0.2 mS/m KCl buffer yield a nanoparticle conductivity of 26 mS/m that lies within 8% of the expected value. The results show that the dual-frequency method has considerable promise particularly for automated DEP investigations and associated technologies.

Type: Article
Title: Dual-cycle dielectrophoretic collection rates for probing the dielectric properties of nanoparticles
Open access status: An open access version is available from UCL Discovery
DOI: 10.1002/elps.201200422
Publisher version: http://dx.doi.org/10.1002/elps.201200422
Language: English
Additional information: © 1999-2013 John Wiley & Sons, Inc. All Rights Reserved. PubMed ID: 23172363
Keywords: AC electrokinetics, Amplitude modulation, Dielectrophoretic spectroscopy, Nanoparticle characterization, Pulsed dielectrophoresis
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology
URI: http://discovery.ucl.ac.uk/id/eprint/1406300
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