Magnetic-fluid microelectrornechanical light modulator

Abstract

A microfluidics microelectromechanical light modulator using a magnetic fluid is introduced. The optical reflection from the device is modulated by applying an electric current into an electrode, which is enclosed by ferromagnetic thin films as in an inductive head for a magnetic data storage device. The magnetic field produced by the current exerts a magnetic force on the magnetic fluid and drives the fluid to cover the cell surface. The surface tension of the fluid provides a restoring force when the field is reduced. The actuation of the fluid is completed in about 12 ms for both thin-to-thick and thick-to-thin fluid film switchings by magnetic forces and surface tension forces, respectively. It was observed that the switching speed was almost independent of the driving current, and no considerable thermal effect were observed when the current is up to 100 mA.