Formation of multilayer aggregates of mammalian cells by dielectrophoresis

The formation of aggregates of mammalian cells at interdigitated oppositely castellated electrodes by positive dielectrophoresis was investigated. It is shown that, by using a constant small flow of fresh sorbitol iso-osmotic buffer through the chamber to remove ions leaking from the cells, a high positive DEP force can be maintained throughout the formation of the aggregates. Flow-rate dependent optima were found in the aggregate height as a function of the electrode size. It is shown that at low flow rates the creation of aggregates of mammalian cells with heights over 150 νm is feasible using relatively low voltages (20 Vpk-pk, 1 MHz). The formation of layered aggregates of two specialized cell types - stromal cells and Jurkat T lymphocytes - is demonstrated. The work confirms that dielectrophoresis can be reliably used for the formation of aggregates with three-dimensional architectures, which could be used as artificial microniches for the study of interactions between cells. © 2006 IOP Publishing Ltd.