In recent decades the effects of magnetic and electric fields on living cells and organisms have gained the increasedattention of researchers. In recent years, dielectrophoresis based microfluidics systems have been used to manipulatebiological micro particles, such as red blood cells, white blood cells, platelets, cancer cells, bacteria, yeast, microorganisms, proteins, DNA, etc. So most previous researchers have studied particle trajectory under theapplication of electric field in order to better design of such micro devices. In the current study the effect of nonuniformelectric field on a single cell is investigated. A neutral particle polarizes in the presence of electric field. It causes localchange in electrostatic potential distribution and local nonuniformity in electric field. These changes are ignored inprevious researches and effective dipole moment (EDM) approximation is applied to predict the DEP force exerted oncells. In the present research the effect of cell on electrostatic potential distribution and electric STRESSes acting on cellsurface is studied. To this end, the cell shape and internal boundary conditions on cell surface must be considered incomputational domain. To do this, Immersed Interface Method (IIM) which is a modified finite difference method isemployed. Some numerical results are presented to show the good accuracy of mentioned numerical method. Theelectric STRESSes on cell surface are calculated by MAXWELL STRESS TENSOR (MST). Also some results are presented tovalidate the numerical solution and investigate the accuracy of EDM approximation. Other electrokinetic effects suchas electrophoresis and electro-osmosis are neglected in this study.