The movement of a biological cell suspended in the medium is governed by several factors: movement of the medium, gravity, electric force, Van der Waals force, and affinity to the surface. Various methods have been applied to control the movement of cells in vitro: the flow, the shear field, the filter, the slit, the magnetic field, the gravitational field, laser, and the electric field. These methods might contribute to several applications of manipulation of cells: detection of targeted cells, sorting of cells, arrangement of cells to make a tissue, and measurement of the character of cells. Movement of a charged particle depends on the electric field. The effect is applied to the electrophoresis device. When a particle is subjected to a non-uniform electric field, a force acts even on a non-charged particle, because the polarization generates in the particle. The phenomenon is called dielectrophoresis. The force of dielectrophoresis depends on the several parameters: the electrical property of the particle, shape and size of the particle, the electrical property of the medium, and the electric field (the amplitude and the frequency). Electrophoresis is a phenomenon, in which a particle is moved by the Coulomb force between the charge of the particle and the electric field. Dielectrophoresis, on the other hand, is a phenomenon, in which a particle moves due to the interaction between the electric field and the charge induced in a neutral particle, when the particle is placed in a non-uniform electric field.With the aid of the micromachining technique, many kinds of micro systems were designed. In some systems, dielectrophoresis was applied to sort biological cells floating in the medium. In the present study, the flow channel for cell sorter by dielectrophoresis in vitro has been designed with photolithography technique. A pair of asymmetric surface electrodes of titanium (thickness of 200 nm) were incorporated just before the branching flow channel: a triangular electrode with the tip angle of 0.35 rad, and a rectangular electrode of the flat edge as the reference. The cyclic alternating electric current of the square wave (between 0.25 μs and 0.3 μs of periods) was introduced between the surface electrodes. The suspension of C2C12 (mouse myoblast cell line) was injected into the flow channel, and the flow rate was controlled by the pressure head between the inlet and the outlet. Experimental results of the pilot test show that the absolute value of the amplitude of the acceleration by the electric field, which is perpendicular to the flow direction, increases with the radius of the cell. The movement of the floating cell in the electric field depends on its shape. The results would contribute to several applications: sorting of cells, detection of cells for diagnostics.

Movement of Myoblast Flowing Through Electric Field Perpendicular to Flow Channel

Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2021/volume/85284

ASME 2021 Fluids Engineering Division Summer Meeting (FEDSM2021)

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