the induced dipole. When averaged, the effect cancels out and the equation holds true for lossy particles as well. An equivalent time-averaged equation can be easily obtained by replacing E with Erms, or, for sinusoidal voltages by dividing the right hand side by 2. These models ignores the fact that cells have a complex internal structure and are heterogeneous. A multi-shell model in a low conducting medium can be used to obtain information of the membrane conductivity and the permittivity of the cytoplasm. For a cell with a shell surrounding a homogeneous core with its surrounding medium considered as a layer, as seen in Figure 2, the overall dielectric response is obtained from a combination of the properties of the shell and core. where 1 is the core (in cellular terms, the cytoplasm), 2 is the shell (in a cell, the membrane). r1 is the radius from the centre of the sphere to the inside of the shell, and r2 is the radius from the centre of the sphere to the outside of the shell. Applications of dielectrophoresis Dielectrophoresis can be used to manipulate, transport, separate and sort different types of particles. Since biological cells have dielectric properties, dielectrophoresis has many medical applications. Instruments that separate cancer cells from healthy cells have been made. Platelets have been separated from whole blood with a DEP-activated cell sorter. Dielectrophoresis can be used to manipulate, transport, separate and sort different types of particles. DEP is being applied in fields such as medical diagnostics, drug discovery, cell therapeutics, and particle filtration. DEP has been also used in conjunction with the semiconductor chip technology for the development of DEPArray technology (Menarini Silicon Biosystems) for the simultaneous management of thousands of cells in a microfluidic device. Single microelectrodes on the floor of a flow cell are managed by the CMOS chip to form thousands of “Dielectrophoretic Cages”, each capable of capturing and moving one single cell under control of a routing software. The most effort in studying DEP has been directed towards satisfying the unmet needs in the biomedical sciences. As biological cells have dielectric properties dielectrophoresis has many medical applications. Instruments capable of separating cancer cells from healthy cells have been made as well as isolating single cells from Forensic mixed samples. DEP has made it possible to characterize and manipulate biological particles like blood cells, stem cells, neurons, pancreatic β cells, DNA, chromosomes, proteins