During the treatment of cancer, the isolation of metastatic cancer cells (MCCs) during their process of migration is one of the techniques to control the growth of such cells. Among the available techniques of separation, dielectrophoresis (DEP) based cell sorting is one of the popular techniques. Herein, we also employ the DEP-based separation method in a microfluidic platform to separate MCC like MDA-MB-231 from white blood cells (WBCs). However, the main objective of the study is to achieve a high degree of recovery rate, separation efficiency, and purity with a voltage as low as possible to avoid the risk of cell electroporation. The study is carried out numerically using the finite element method that solves the Stokes equation and the Laplace equation. Thereafter, the obtained solution is utilized to track the cell trajectories by solving the force balance equation. The findings infer that a recovery rate of 92%, separation efficiency of 100%, and purity of 98% could be achieved with a voltage of 1.55 V which is much less than that achieved by previous literature.