• Transactions of the KSME C: Technology and Education
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• v.3 no.3
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• pp.217-223
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• 2015

The patterning of microbead in microfluidics channel is a practical technique for application in bio and medical areas. An approach is described for a direct patterning of magnetically active microbeads in microfluidic devices without inner structure. Local magnet arrangements - flat arrangement and stack arrangement - contacting same poles or opposite poles of magnet were utilized for generating trapping magnetic fields. The arrangement of magnets contacting same poles generated isolated patterns by repelling of magnetic field. The flat arrangement of vertically reverse magnet arrays shaped trapping patterns repelling magnetic field line between same poles. Spatially, the stack compositions of magnet arrangements allow diverse isolated trapped patterns of magnetic particles. Trapped magnetic particles in fluidic channels were stable on the $18m{\ell}/hr$ flow conditions and magnetic force of 1.08 mT in the all experiments. This experimental study suggests the simple and versatile methods to pattern magnetic particles, and has potential of wide application to bio and medical area.

• Journal of the Korean Society of Visualization
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• v.17 no.1
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• pp.69-77
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• 2019

This paper introduces microfluidic manipulation of microorganism by opto-electrokinetic technique, named rapid electrokinetic patterning (REP). REP is a hybrid method that utilizes the simultaneous application of a uniform electric field and a focused laser to manipulate various kinds and types of colloidal particles. Using the technique in preliminary experiments, we have successfully aggregated, translated, and trapped not only spherical polystyrene, latex, and magnetic particles but also ellipsoidal glass particles. Extending the manipulation target to cells, we attempted to manipulate saccharomyces cerevisiae (S. cerevisiae), the most commonly used microorganism for food fermentation and biomass production. As a result, S. cerevisiae were assembled and dynamically trapped by REP at arbitrary location on an electrode surface. It firmly establishes the usefulness of REP technique for development of a high-performance on-chip bioassay system.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.9.2-9.2
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• 2011

Ultrathin polyelectrolyte (PE) multilayer films prepared by the versatile layer-by layer (LbL) assembly method have been utilized for the preparation of light-emitting diodes, electrochromic, membrane, and drug delivery system, as well as for selective area patterning and particle surface modification because the various materials with specific properties can be inserted into the film with nano-level thickness irrespective of the size or the shape of substrate. Since the introduction of the LbL technique in 1991 by Decher and Hong, various hydrophilic materials can be inserted within LbL films through complementary interactions (i.e., electrostatic, hydrogen-bonding or covalent interaction). In this study, it is demonstrated that LbL SA multilayer films based on nucleophilic substitution reaction can allow the preparation of the highly efficient magnetic and/or optical films and nonvolatile memory devices.