Optimization of ferrofluid motion on solid substrate and its application to micro-mirror device

Abstract

This paper presents and demonstrates the optimization of an oil-based ferrofluid droplet on a solid surface and its application to a micro-mirror device with a fast switching time. The motion of the ferrofluid droplet on a hydrophilic surface was examined at various surfactant concentrations for both rotational and linear reciprocating actuations. A maximum moving speed of 0.733 m/s was measured at a poly(vinyl alcohol) (PVA) concentration of 0.1 wt % during the rotational motion of the ferrofluid droplet. In addition, a fast reciprocating motion was successfully demonstrated during the linear operation experiment without droplet separation or surface contamination. A maximum acceleration and deceleration of 28 m/s 2 was measured at a PVA concentration of 0.1 wt %. As an application of the fast motion of the ferrofluid, a current-driven micro-mirror was proposed and experimentally demonstrated. Switching times of 25 and 18 ms were measured for the closing and opening phases of the mirror, respectively.

Large-Area Optical Switch Using Surface-Expandable Liquid Droplets

“…Therefore a liquid based optical switch is polarization-insensitive. Numerous papers have been published about an optical switch and/or display using a shape-expandable liquid [1][2][3][4][5][6]. However, the previously demonstrated devices are about only one liquid droplet or a single pixel for R, G, and B light switches.…”