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

Abstract

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. Published by AIP Publishing.

Design of a Multiplexed Analyte Biosensor using Digital Barcoded Particles and Impedance Spectroscopy

“…Finally, by employing a top-bottom microelectrode apparatus, microspheres are detectable both above and below the barcoded particle. While the fabrication of top and bottom electrodes for microfluidic applications are infrequent, recent studies have found effective means to produce results using glass-embedded electrodes sandwiching PDMS-based channels, and we believe such methods are possible for in vitro design experiments 49 . Furthermore, our top-bottom electrode configuration is independent of vertical alignment between electrodes as both systems emit/detect their own electric field areas, reducing the burden of micron-scale alignment protocols and promoting simpler microfluidic manufacturing.…”

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

“…A shorter electrode substrate was used to investigate the dielectrophoretic behavior of cells and to explore the optimal operation condition and the optimal length of the flow chamber for a high throughput cell separation, while the longer one was used for the quantitative evaluation of the separation performance of the proposed device. The length of the shorter electrode substrate was determined by taking into account the results of the yeast-cell separation; 16 the length of the electrode longer than the previously used one was found to be necessary for mammalian cells. The shorter interdigitated electrodes were fabricated in a similar manner by standard photolithography.…”

“…We used a three-dimensional (3D) nonuniform AC electric field established in the whole volume of a parallel-plate type flow chamber to enhance the process of cell separation. 15,16 In general, the ideal DEP cell-separation device aimed at clinical applications would take the best advantage of the field gradient established in the flow chamber to manipulate cells without damaging them by joule heating or high voltage. In the proposed method, the electric field creates sites of minimum field gradient in the middle of the flow stream slightly above the bottom face of the flow chamber, while simultaneously creating sites of the maximum field gradient on the edges of the interdigitated electrode arrays at the bottom face.…”

“…These thermo-fluid mechanical factors have represented major bottlenecks in designing new DEP cell-separation devices to rapidly process a large volume sample when necessary. Our previous study 16 demonstrated that nonviable (dead) yeast (Saccharomyces cerevisiae) cells traveling in the flow stream were concentrated around the sites of the minimum field gradient slightly above the bottom of the flow chamber and were separated from the viable (live) yeast cells that are attached to the edges of the fingers of the interdigitated electrodes at the bottom face. In that study, the dead cells traveling through the flow chamber were separated from the live cells using the corresponding 3D nonuniform electric field with an applied voltage of 3 V peak-to-peak and a frequency range of 1-100 MHz.…”

“…In the present study, in order to examine the operation and performance of the proposed cell-separation DEP device as the practical tool for medical applications, live and dead human breast epithelial (MCF10A) cells were used. Because the dielectrophoretic characteristics of the human cells in response to the electric field are quite different from those of yeast cells, two different types of parallel-plate type DEP flow-chambers were newly developed in accordance with our previously proposed design of the device 16 to investigate the cell behavior and the device performance. In developed devices, dead (nonviable) cells were trapped on the edges of electrodes at the bottom face and were separated from live (viable) cells traveling in the flow stream at the height of the equilibrium.…”