This paper presents the design and characterization of microsystems for the analysis of biological cells using dielectrophoresis techniques in a microfluidic environment. Dielectrophoresis is an electrokinetic technique used to manipulate cells which are electrically polarized when they are subjected to a non-uniform electric field. As the movement of cells is related to their dielectric properties, the study of cell dielectrophoretic behaviour appears as an attractive method for their characterization. In this paper, microsystems dedicated to the study of cell dielectrophoretic behaviour are studied. At first, devices have been investigated using polystyrene beads. In a second step, the behaviour of cancerous colorectal cells (SW-620 cell line) will be analysed and first results obtained in the 10 kHz to 10 MHz frequency range will be presented.