Transparent Multilevel Aligned Electrode Microfluidic Chip for Dielectrophoretic Colloidal Handling

Spatial localization and handling of cells and colloid trajectories in a microfluidic channel are required to fully control their interactions at a single level. This paper presents a novel transparent multilevel aligned electrode microfluidic chip that is fast to process and reusable, with which high throughput for dielectrophoretic handling of polarizable particles can be achieved. Performances of the chips are evaluated by electrical impedance measurements and light diffusion characterizations. The observation of the Indium Tin Oxyde (ITO) electrode degradation process allows a better understanding of the behavior of ITO at low frequencies. Electrical and optical characterizations confirmed that this process is a redox reaction of indium that seriously alters the conductivity and the transparency of the ITO layer in the microfluidic chip. A safe range of AC-voltage frequencies is given for dielectrophoretic handling. Finally, we demonstrate within this chip focalization and stop-and-go functions for 1 μm polystyrene colloidal particles.