Focusing of biological cells utilizing negative dielectrophoretic force generated by insulating structures

The main purpose of the present study is to design an insulator-based dielectrophoretic microdevice with effective focusing of biological cells. The cells are introduced into the microchannel and pre-confined hydrodynamically by the funnel-shaped insulating structures close to the inlet. The cells are, therefore, repelled toward the center of the microchannel by the negative dielectrophoretic forces generated by the insulating structures. The increase in the applied electric field significantly enhances the performance of focusing. Furthermore, decreasing inlet velocity increases the efficiency of focusing because the higher velocity results in more lateral expansion. Preliminary experiments employing viable HeLa cells are conducted in order to demonstrate the feasibility of the present design. Experimental results indicate that the performance of focusing increases with the strength of the electric field applied or with a decrease in the inlet velocity. The experimental results agree with the predictions by numerical simulations. The design proposed herein has no need for complicated flow controls to focus the cells.