Dielectrophoresis-based separation of microparticles and living cells are studied with computational and experimental methods. The flow behaviours of particles are modelled and simulated using COMSOL Multiphysics 4.3a software (COMSOL Ltd). Lab-on-a-chip devices having a titanium (Ti) interdigitated electrode layer on a glass substrate and a PDMS microchannel are fabricated to investigate the most effective design for separating particles based on their sizes. Polystyrene particles in different diameters (3.2 and 9.8 mu m) are used in the experiments. Green polystyrene particles from red ones are fully separated in a current design. Enrichment of Jurkat cells having 10.1 average diameter in phosphate buffer solution (PBS) medium is achieved.