Dielectrophoretic separation and manipulation of live and heat-treated cells of Listeria on microfabricated devices with interdigitated electrodes

Dielectrophoresis, the movement of particles in non-uniform ac electric field, was used to separate live and heat-treated Listeria innocua cells with great efficiency on the micro-fabricated devices with interdigitated electrodes by utilizing the difference of dielectric properties between alive and dead cells. Both live and dead cells are found to be only able to collect either at the centers of the electrodes in negative dielectrophoresis or at the electrode edges in positive dielectrophoresis due to the dielectrophoretic force and electrohydrodynamic force. Cell viability was verified by a rapid method using epifluorescence staining. The dependency of the applied ac signal's frequency on the dielectrophoretic properties of Listeria cells is studied and discussed. This on-electrode manipulation and separation of cells can prove to be useful in micro-scale sample preparation and diagnostic applications in biochips.