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Kanokkan Maswiwat

Electromanipulation of Ellipsoidal Cells in Fluidic Micro-Electrode Systems

Universität Rostock, 2007

Abstract: Recently, electromanipulation technologies for handling and characterizing individual cells or particles have been applied to lab-on-chip devices. These devices play a role in pharmacological and clinical applications as well as environmental and nanotechnologies. Electromanipulation of ellipsoidal cells in fluidic micro-electrode systems has been studied by numerical simulations, theoretical analysis and experiment. The field distributions in electrorotation chip chambers were analyzed using numerical field simulations in combination with analytical post-processing. The optimal design for two-dimensional electrorotation chips features electrodes with pyramidal rounded tips. Moreover, the three-dimensional electric field distributions in the electroporation and electrorotation chambers were analyzed. The advantage of electroporation chip chambers is to avoid strongly increasing temperatures after pulse application. New chips may be developed for nanoscale applications in the future. New simplified analytical equations have been developed for the transmembrane potential (delta_phi) induced in cells resembling ellipsoids of rotation, i.e. spheroids, by homogeneous DC or AC fields. The new equations avoid the complicated description by the depolarizing factors. Also the dielectrophoretic force expression for spheroidal objects has been simplified. Furthermore, the effects of cell orientation and electric field frequency on the delta_phi induced in ellipsoidal cells were studied. Simplified equations were derived. They show that the membrane surface points for the maximum of delta_phi depend on cell shape, cell orientation, electric cell parameters and field frequency. The theoretical results were compared to electropermeabilization experiments with chicken red blood cells. Experiments confirmed that equations for the transmembrane potential were advantageous for describing the transmembrane potential induced in arbitrarily oriented ellipsoidal cells.

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