Arisa Nakanishi’s research while affiliated with National Defense Academy of Japan and other places

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.

In the present study, experimental and numerical studies of dielectrophoretic (DEP) flow channel, a type of cell-separation devices that exploits the differences in the dielectric properties of cells, was conducted to design and propose a high-performance cell-separation DEP device. The cell samples used were live and dead cultured budding yeast cells suspended in water. The cell-separation analysis was carried out for the flow channel equipped with a planar electrode on the top face and an array of micro-fabricated electrodes on the bottom face; yielding a three dimensional non-uniform electric field across the full height of the flow channel. To determine the optimal separation condition for live and dead cell-mixtures, the value of the field frequency was varied in several ways. With the appropriately chosen operating condition, the live cells were effectively attracted toward the edges of electrodes on the bottom while the most of the dead cells continued to travel in the flow. The performance improvement of DEP cell-separation device can be expected by using the concept of the proposed device.