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Dielectrophoretic Particle Filtration in Porous Media (GRK 1860)

Dielectrophoresis (DEP), the migration of polarizable particles in inhomogeneous electric fields, is an effect that allows size- and material-selective manipulation of nano- and microparticles. It therefore provides unique possibilities for purification and recovery of high-value particles. Goal of the project is to investigate the possibilities of particle filtration and recovery by dielectrophoretic trapping in porous structures.

  • As shown in the figure, the porous filter is placed between two electrodes that generate an electric field. By polarization of the filter material the electric field is disturbed resulting in field inhomogeneities that pull particles to the pore wall, where they stay until the electric field is switched off. To prevent mechanical trapping the used particles (diameter: 0.2 µm – 10 µm) are at least one order of magnitude smaller than the pore diameter of the porous structures. This allows switchable filtration with low pressure loss and negligible fouling.

  • Microscopic photograph of fluorescent 5 µm polystyrene particles (green) in a microchannel containing feld disturbing pillars. Without field (left), the particles pass the structure unaffected. When a field is applied (right), particles are trapped due to positive DEP forces at the pillar surfaces.

  • DEP filter chanber containing the porous ceramics sandwiched between the electrodes.

  • Photograph of the ceramic filter.

  • Ceramic filter, colored green due to the amount of trapped particles.

Dielectrophoresis depends on an electric field inhomogeneity, which, in this project, is generated by electric field scattering in the porous medium. So, the porous medium employed in our work acts not only as immobilization matrix but also induces the field inhomogeneities required for DEP movement. In the first phase of the project we investigated the influence of geometry and material of the porous structure on DEP particle trapping by numerical methods. The calculations were validated by experiments in microchannels.

The gained insights are now used to design filters. In experiments we investigate the application of DEP in porous structures for size- and material-selective particle trapping at industrial scale throughputs. This allows for the development of electrically switchable and (material-)selective filters for the recovery of high-value products.

Relevant publications from the project

G.R. Pesch et al. (2014). Sep Purif Technol. 132https://doi.org/10.1016/j.seppur.2014.06.028.
G.R. Pesch et al. (2016). Electorphoresis 37https://doi.org/10.1002/elps.201500313.
G.R. Pesch et al. (2017). J Chrom A 1483https://doi.org/10.1016/j.chroma.2016.12.074.
G.R. Pesch et al. (2018). Sci Rep 8, http://doi.org/10.1038/s41598-018-28735-w.
Georg Pesch's PhD thesis

 

Relevant files

Contact:

Lorenz, Malte, M. Sc.
Room UFT 2190
Phone 0421- 218 - 63392

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