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Issue 6, 2012
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Single particle analysis using fluidic, optical and electrophoretic force balance in a microfluidic system

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Abstract

A unique microfluidic system is developed which enables the interrogation of a single particle by using multiple force balances from a combination of optical force, hydrodynamic drag force, and electrophoretic force. Two types of polystyrene (PS) particles with almost identical size and refractive index (plain polystyrene (PS) particle – mean diameter: 2.06 μm, refractive index: 1.59; carboxylated polystyrene (PS-COOH) particles – mean diameter: 2.07 μm, refractive index: 1.60), which could not be distinguished by optical chromatography, reveal different electrokinetic behaviors resulting from the difference in their surface charge densities. The PS-COOH particles, despite their higher surface charge density when compared to the PS particles, experience a lower electrophoretic force, regardless of ionic strength. This phenomenon can be understood when the more prominent polarization of the counter ion cloud surrounding the PS-COOH particles is considered. The surface roughness of the carboxylated particles also plays an important role in the observed electrokinetic behavior.

Graphical abstract: Single particle analysis using fluidic, optical and electrophoretic force balance in a microfluidic system

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Publication details

The article was received on 20 Oct 2011, accepted on 10 Jan 2012 and first published on 08 Feb 2012


Article type: Paper
DOI: 10.1039/C2LC21017G
Citation: Lab Chip, 2012,12, 1128-1134

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    Single particle analysis using fluidic, optical and electrophoretic force balance in a microfluidic system

    Q. Lu, A. Terray, G. E. Collins and S. J. Hart, Lab Chip, 2012, 12, 1128
    DOI: 10.1039/C2LC21017G

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