Studies of particle holding, separating, and focusing using convergent electrodes in microsorters

This paper presents numerical simulation results on the efficacy of dielectrophoretic (DEP) convergent electrodes in a particle sorter. DEP forces created by non-uniform electric fields are used as holding forces to trap and select the particles from a mixture of many samples, as well as confining forces to focus the particles into a single particle stream in the microsorter for further analysis. The key mechanism of the sorter that can hold particles against destabilizing fluid flows is investigated in this study. A barrier is found at X/L =0.84 and Y =0 in the present DEP sorter. By comparing the DEP and hydrodynamic forces at the barrier, one can determine the release velocity when the zero-net-force condition ceases to exist and the particles start to be released.