A Concept of Moving Dielectrophoresis Electrodes Based on Microelectromechanical Systems (mems) Actuators

A concept of moving dielectrophoresis electrodes (MDEP) based on Microelectromechanical Systems (MEMS) actuators is introduced in this letter. An example design of tuneable dielectrophoresis filter is presented. Finite Element Analysis of the electrostatic field of the tuneable filter has been conducted. Results show that the trapping force can be adjusted by actuating the MEMS actuators. The principle of the dielectrophresis (DEP) is based on polarization of the dielectric particles under electrostatic field. Polarized dielectric particles can be moved toward the direction of the electric field gradient. Examples of polarized objects include dielectric materials, metallic particles, and many biological objects, such as nucleic acids, proteins, cells, and virus. DEP has been proven to be a powerful technique to perform sample sorting, trapping, manipulation, and concentration [1]. The classical DEP has been expanded to travelling wave DEP in order to get high throughput cell manipulation without external liquid pumping [2], CMOS DEP in order to achieve parallel manipulation of large number of cells [3], and laser induced DEP by optically programmable electrodes [4]. Microfabricated interdigitated electrode array was introduced previously [5] for application of separating two populations of particles pumped across the electrode array, one population of particles having positive dielectrophoresis and another having negative dielectrophoresis. The above approaches are all based on fixed electrodes arrangement. A concept of moving dielectrophoresis electrode (MDEP) is introduced based on microelectromechanical systems 90 Li and Uttamchandani (MEMS) electrostatic or electrode thermal actuators in this letter. The electrostatic or electrothermal actuators were previously operated under the water [6], which proves the idea of MDEP very feasible. Previous research on interdigitated electrodes [7] shows that the DEP force changes with electrode dimensions (electrode width and gap) at a given voltage. If for example, the gap of the electrodes changes, the trapping force will also changes accordingly. A tuneable DEP filter as an example of MDEP is therefore generated, which is schematically shown in Figure 1. Direction of moving MEMS actuator Interdigitated electrode array Inlet Outlet Cavity