Particle Immobilization Stiffness in Dielectrophoresis Trap Depending on the Geometry

In dielectrophoresis, a neutral particle experiences a partial charge separation, i.e. induced net dipole moment, when exposed to a non-uniform electric field, and this leads translational movement of the particle. This induced attractive or repulsive motion of the particle suspended in a fluid is known as dielectrophoresis (DEP). In this paper, we have characterized the strength of DEP traps depending on geometry. Three different micro-trap geometries, i.e. triangle, square and circle, were tested to characterize the effect of trap shape on trap stiffness experimentally and numerically using single particle immobilized in the trap. The maximum DEP force generated in triangular μ-trap was found largest among tested geometries. The maximum DEP force of square and circular trap was found around 68.4% and 79.1% of triangular μ-trap, respectively. The trajectory analysis using trapped single particle revealed that the stiffness of circular μ-trap is 1.23 and 1.34 times stronger than the triangular and square μ-trap, respectively. These results will provide useful information in DEP trap geometry designing to enhance trapping efficiency.