Centrifugation and Negative-Dielectrophoresis Assisted Cell Separation Method

Cell size is an important parameter for cell analysis and manipulation. Cell sample with similar size distribution can improve the performance in cell screening, cell electroporation and electrofusion. One approach for cell purification is to utilize constriction structures such as dams to trap cells in microfluidics. This paper presents a centrifugation and negative-dielectrophoresis assisted size-based cell separation method. The goal is to separate cell sample and get purified cells by size-based screening. We designed and fabricated a microfluidic chip with five octagon-shape screening-dams within a flow-through channel network. The radius of the octagon was from 10mm to 26mm, and the array space was 4 mm. The octagon-shape screening-dam contained hundreds of micro-filter and micro-dam structures. Each micro-filter was composed by two micro-dam structures. The width of filter between two adjacent micro-dams is 40, 30, 20, 15, 10 mm, respectively. After loaded cell sample into the central reservoir, the microfluidic chip was revolved in high speed. Cells with big size were immobilized and captured into micro-filter under centrifugal force. To avoid too much cells are concentrated into micro-filters and blocked these structures, negative-dielectrophoresis was applied per 2 minutes, to push cell leave to filter and move into independent chamber between two adjacent octagon-shape screening-dam arrays. In the end, purified cells with similar size were separated and collected into each independent chambers.