NE461 Lecture Notes - Lecture 10: Vacuum Permittivity, Dielectrophoresis, Relative Permittivity

• School: University of Waterloo
• Department: Nanotechnology Engineering
• Course: NE461
• Professor: Juewen Liu

Document Summary

Some (undesired) properties of electrophoresis (ef): electrophoresis requires charged particles/molecules. So, it is more difficult to manipulate and separate different cells using ef. This is important because it limits side reactions in water for microfluidic devices: the frequency of the applied field is another variable to control dep. The term dielectrophoresis (dep) refers to the coulomb response of an electrically polarized object in a nonuniform electric field. Dielectrophoretic force (def) is the interaction between induced dipoles and applied electric field. Dep is often used in microsystems as a mechanism for manipulating particles. Consider, a spherical, uncharged, uniform, ideal dielectric particle with a finite polarizability, expressed using its electrical permittivity p, suspended in empty space. If a uniform electrical field is applied to this system, the particle polarizes. A net positive charge is present at one end of the sphere whereas a net negative charge is present on the other end of the sphere.