Masanori Eguchi

Separation of Leukemia Cells from Blood by Employing Dielectrophoresis

Our goal is development of a new automatic blood cell counter that it can detect a small amount of leukemia cells in the blood of patients. We employ the dielectrophoresis (DEP). In this paper, we examine whether or not realization that a living blood cells are separated by employing the dielectrophoresis. Leukocyte and erythrocyte are separated by dielectrophoresis under 60MHz, 10Vpp. Furthermore, normal leukocytes and BALL-1 which is one kind of leukemia cells were separated under 37KHz,14Vpp

Enhancement of continuous-flow separation of viable/nonviable yeast cells using a nonuniform alternating current electric field with complex spatial distribution

The variability in cell response to AC electric fields is selective enough to separate not only the cell types but also the activation states of similar cells. In this work, we use dielectrophoresis (DEP), which exploits the differences in the dielectric properties of cells, to separate nonviable and viable cells. A parallel-plate DEP device consisting of a bottom face with an array of micro-fabricated interdigitated electrodes and a top face with a plane electrode was proposed to facilitate the separation of cells by creating a nonuniform electric field throughout the flow channel. The operation and performance of the device were evaluated using live and dead yeast cells as model biological particles. Further, numerical simulations were conducted for the cell suspensions flowing in a channel with a nonuniform AC electric field, modeled on the basis of the equation of motion of particles, to characterize the separation efficiency by changing the frequency of applied AC voltage. Results demonstrated that dead cells traveling through the channel were focused onto a site around the minimum electric field gradient in the middle of the flow stream, while live cells were trapped on the bottom face. Cells were thus successfully separated under the appropriately tuned frequency of 1 MHz. Predictions showed good agreement with the observation. The proposed DEP device provides a new approach to, for instance, hematological analysis or the separation of different cancer cells for application in circulating tumor cell identification.

High-throughput separation of cells by dielectrophoresis enhanced with 3D gradient AC electric field

We propose a novel, high-performance dielectrophoretic (DEP) cell-separation flow chamber with a parallel-plate channel geometry. The flow chamber, consisting of a planar electrode on the top and an interdigitated-pair electrode array at the bottom, was developed to facilitate the separation of cells by creating a nonuniform AC electric field throughout the volume of the flow chamber. The operation and performance of the device were evaluated using live and dead human epithermal breast (MCF10A) cells. The separation dynamics of the cell suspension in the flow chamber was also investigated by numerically simulating the trajectories of individual cells. A theoretical model to describe the dynamic cell behavior under the action of DEP, including dipole-dipole interparticle, viscous, and gravitational forces, was developed. The results demonstrated that the live cells traveling through the flow chamber congregated into sites where the electric field gradient was minimal, in the middle of the flow stream slightly above the centerlines of the grounded electrodes at the bottom. Meanwhile, the dead cells were trapped on the edges of the high-voltage electrodes at the bottom. Cells were thus successfully separated with a remarkably high separation ratio (∼98%) at the appropriately tuned field frequency and applied voltage. The numerically predicted behavior and spatial distribution of the cells during separation also showed good agreement with those observed experimentally.

Separation of Particles Employing Travelling-Wave Electrokinetic Phenomena and Inclined Gravity

In travelling-wave electric fields, particles are propelled along electrode arrays by a propulsion force. The propulsion force depends on an applied frequency, voltage and size of particles. In this paper, we present the separation method of micro particles using the propulsion force and inclined gravity. The suspensions of polystyrene beads were used as the method to demonstrate the general application for the selective retention or transportation of particles. The efficiency of the method depends on the size of particles and mass density of particles. Additionally the method can measure the propulsion force on particles by adjusting the inclined angle.

Analysis of the dielectrophoretic properties of cells using the isomotive AC electric field

Various microfluidic devices utilizing the principle of dielectrophoresis (DEP) have been developed to separate, concentrate, and characterize biological cells; however, their performance is still limited by a lack of quantitative characterization. We addressed this limitation by employing a method capable of accurately quantifying a cells response to an imposed field gradient. In this study, a simple method using a newly designed Creek-gap electrode was proposed, and the electrokinetic behavior of cells was characterized by DEP velocimetry under the exposure of an approximately constant gradient of electric field square established along the gap of the electrodes. Together with the numerical prediction of the electric field based on three-dimensional electric field analysis, the magnitude of DEP forces and the real part of the Clausius-Mossotti factor of cells were deduced from their movement. Results demonstrated that the proposed method was applicable to the determination of the dielectrophoretic properties of cells.

Development of microwell array for dielectric characterization of circulating tumor cells

Electrorotation is a noninvasive technique to measure the dielectric properties of biological cells. In this paper, We fabricate an electrorotation microwell array for high-throughput dielectric characterization of circulating tumor cells (CTCs). The device consists of a microwell array and electrorotation chip. The practicality of the device was evaluated using PC-9 cells. The PC-9 cells were captured single cells in the microwells and measured electrorotation spectrum, which reflects its dielectric properties.

Design and evaluation of electrode for dielectrophoretic characterization of blood cells

Dielectrophoresis can be used to determine the dielectric properties of biological cells. In this paper, we present an electrode design for characterization of blood cells by measuring negative dielectrophoretic force. The negative dielectrophoretic force acting on glass beads in distilled water was measured by inclined gravity to evaluate the effectiveness of the designed electrode. The designed electrode generated the negative DEP force ranging from 0.21 pN to 1.89 pN with 20 Vpp, 1 MHz. The distribution of the dielectrophoretic force was consistent with the calculated results.

Design of ceiling electrode for cell separation using positive Dielectrophoresis and inclined gravity

Dielctrophoresis (DEP) is a movement of particles in medium by a force, which is generated in non-uniform electric fields. The Dielectrophoretic force (DEP force) depends on the geometry of an electrode. In this paper, the design and the simulation of the ceiling electrode to separate biological cells by using positive dielectrophoresis and inclined gravity are presented. The positive DEP force which is generated around the designed ceiling electrode is measured by inclined gravity.

Radiation characteristics of NRD compatible pyramidal horn antenna for multiple access LAN applications at 60 GHz

A technique to control the radiation pattern of an NRD guide compatible pyramidal horn antenna, which consists of a tapered dielectric rod inserted into the horn, has been developed for multiple access LAN applications at 60 GHz. It has been found that the phase distribution on the aperture of the horn is influenced by the dielectric rod, and, thus, the radiation pattern can be changed by shifting the length of the dielectric rod inserted into the horn. By using such a simple method, the half-power beam-width can be controlled from 11/spl deg/ to 40/spl deg/.