J2230103 Fundamental characteristics of a polyimide diaphragm actuator using a magnet surrounded by magnetic fluid layer

Abstract

A magnetic microelectromechanical systems (MEMS) actuator using a small permanent magnet surrounded by magnetic fluid was developed and characterized. The magnet is enclosed in a cavity sandwiched by two identical thin film polyimide diaphragms and is able to move smoothly due to the MF. The diaphragm deflects when an external magnetic force is applied to the magnet. This structure was adopted to prevent the diaphragms from being stiffened by attaching or fabricating a magnetic layer on the diaphragm surface and to enable the magnet to move arbitrarily. The magnet is 3 mm in diameter and the diaphragm is 5 mm in diameter (8.5 μm in thickness). Experiments showed the displacement amplitude generated at the diaphragm center was in the range of 5-250 μm when magnetic flux density of 4-30 mT was applied. The diaphragm also could produce the displacement corresponding with the applied rotating external magnetic field (2 Hz).