Polarizability-Dependent Sorting of Microparticles Using Continuous-Flow Dielectrophoretic Chromatography with a Frequency Modulation Method

Jasper Giesler,Jorg Thöming,Laura Weirauch,Marc-Peter Schmidt,Georg R Pesch,Michael Baune

doi:10.3390/mi11010038

Jasper Giesler, Jorg Thöming + Show 4 more

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https://doi.org/10.3390/mi11010038

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Abstract

The separation of microparticles with respect to different properties such as size and material is a research field of great interest. Dielectrophoresis, a phenomenon that is capable of addressing multiple particle properties at once, can be used to perform a chromatographic separation. However, the selectivity of current dielectrophoretic particle chromatography (DPC) techniques is limited. Here, we show a new approach for DPC based on differences in the dielectrophoretic mobilities and the crossover frequencies of polystyrene particles. Both differences are addressed by modulating the frequency of the electric field to generate positive and negative dielectrophoretic movement to achieve multiple trap-and-release cycles of the particles. A chromatographic separation of different particle sizes revealed the voltage dependency of this method. Additionally, we showed the frequency bandwidth influence on separation using one example. The DPC method developed was tested with model particles, but offers possibilities to separate a broad range of plastic and metal microparticles or cells and to overcome currently existing limitations in selectivity.

Highlights

Separating microparticles according to specific properties such as size, material, and shape is a research area of great interest for instance in cell or biomolecule manipulation [1,2,3,4,5] and waste recovery [6,7]
The electrode chip forms the bottom of a microfluidic device, where a polydimethylsiloxane (PDMS) channel is used as the separation column
We further show the separation of predominantly nDEP experiencing particles (10 μm) from particles experiencing balanced pDEP/nDEP

Summary

Introduction

Separating microparticles according to specific properties such as size, material, and shape is a research area of great interest for instance in cell or biomolecule manipulation [1,2,3,4,5] and waste recovery [6,7]. A related technique to manipulate micrometer sized particles is using traveling wave dielectrophoretic separators [29,30] In these microfluidic devices, a 90◦ phase angle is present between adjacent electrodes, which changes the dielectrophoretic movement a particle experiences [31,32]. A 90◦ phase angle is present between adjacent electrodes, which changes the dielectrophoretic movement a particle experiences [31,32] Such traveling wave systems offer versatile particle separation techniques, but are usually complex to fabricate and operate [30,33]. The other presented dielectrophoretic chromatography techniques have in common that they depend on strongly diverging polarizabilities (e.g., one type of particle showing positive dielectrophoresis, whereas the other particles show negative dielectrophoresis or exhibit no dielectrophoretic movement) This requirement limits the applicability when addressing particle mixtures with less pronounced differences in polarizability. Addressing binary (or more) mixtures in which there is heterogeneity in the two (or more) classes is even more complex, especially when the cross-over frequencies of the classes are so close that the heterogeneity causes an overlap (an example is the separation of cells according to only small differences in their expression)

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