Research On Cell Separation Dielectrophoresis Microfluidic Chip Based On Conductive Polymer

Cell separation of a purified target cell group from a sample mixture plays a pivotal role in biomedical research,clinical practice as well as demands from homeland securities such as pathogenic bacteria monitoring in food and water quality analysis.Microfluidic cell separation device offers improved separation purities using miniaturized and integrated platform with dramatically reduced sample volume.Dielectrophoresis(DEP)has been recognized as a powerful technique for label-free cell separation in microfluidics.Conducting polydimethylsiloxane(PDMS)composites are favorable due to the relatively simple and low-cost soft-lithography process.Yet existing devices incorporating electrodes in conducting PDMS generally require extra lithography of sacrificial layer on the semi-finished master for molding the electrode and fluidic sidewalls in separate steps.In this article,we demonstrate a novel microfluidic DEP separator with 3D electrode and fluidic structure entirely integrated within silver-PDMS composites.We develop a low-cost,one-step molding process with a readily used SU-8 master,eliminating the need for the additional lithography step in the existing techniques.In this article,the device has uniquely designed two-layer interdigitated digits.The microelectrodes not only provides an efficient dielectrophoretic force field,but also acts as fluidic boundaries defining parallel flow paths penetrating the lower layer.We design experiments and verify that such design is capable of projecting spatially non-uniform electric field that leads to highly effective cell separation in both lateral and vertical directions.Moreover,our experiments evaluated the effect of the upper layer thickness on cell capture efficiency.We demonstrate that the electrode digits with scaled-up flow path number maintain high capture efficiency of 95.4%for live cells with 85.6%purity in separation of live/dead Hela cells.In combination with computer image processing technology,we developed a program to assist in counting video sequences of escaped cells.We also investigate the device feasibility in viability assay for cells post anti-cancer drug treatment.