Continuous cell separation chips using differential dielectrophoretic affinity

Abstract

We present continuous cell separation chips using dielectrophoresis (DEP). Previous DEP cell separation chips are based on the discontinuous cell mixture flow controlled by microfluidic components and require the larger electrode area for the higher throughput screening. The present continuous cell separators have reduced the numbers of microfluidic components and have realized high-throughput screening by increasing the flow-rate over small electrode area. We design two different types of the continuous cell separators: the two-electrode separator and three-electrode separator. The cells in negative DEP affinity are separated from the centerline of the mixture flow stream in the two-electrode separator, while the cells in positive DEP affinity are separated from the central stream line in the three-electrode separator. In the experimental study, we use the mixture of viable (live) and nonviable (dead) yeast cells as sample cells to be separated. We obtain the continuous cell separation conditions in the DEP affinity test for the yeast mixture: the electric field frequency of 5MHz for the sinusoidal potential of $8V_p-p$ across the electrode array of 20㎛ gaps immersed in the medium conductivity of 5μS/cm. Viable yeast cells show the positive DEP affinity while nonviable yeast cells show the negative DEP affinity under these conditions. We observe that two-electrode separator cannot separate the nonviable yeast cells, since the negative DEP force acting on the nonviable yeast cells is too week to overcome the potential barrier at the electrode edges. Using the three-electrode separator, we separate the viable and nonviable yeast cells from the mixture at the flow rates of 0.1, 0.5, and 1㎕/min. Purity of the separated viable cells has been in the range of 95.9~97.3% and that of the separated nonviable cells is measured in the range of 64.5~74.3%. We also find that the purity of the separated viable yeast cells is maintained for the increased flow rate, while that...