Effect of Insulating Post Shape On Particle Trapping With Insulator-Based Dielectrophoresis

Microfluidics is a rapidly growing field, electrokinetic techniques such as electrophoresis, electroosmosis and dielectrophoresis are becoming increasingly important due to their great flexibility. Dielectrophoresis (DEP) refers to particle movement due to polarization effect when particles are exposed to non-uniform electric fields. In insulator-based dielectrophoresis (iDEP) non-uniform electric fields are created by employing 3-dimensional insulating posts between two electrodes. The effect of the separation distance between insulating posts on the dielectrophoretic force force acting on particles and the effectiveness of iDEP techniques is well known. The present research studies the effect of the post geometry on the dielectrophoretic force and particle immobilization. Manipulations of inert polystyrene particles was carried out in microchannels containing arrays of insulating posts that had an effective diameter of 450 µm with a distance between the posts of 50 µm in all cases. Insulating post shapes including circle, diamond, half circle and triangle (half diamond) were compared. In addition to the experimental work, COMSOL software was used to model the electric field gradients and DEP force generated by each post geometry.