Microelectromechanical-System-Based Variable-Focus Liquid Lens for Capsule Endoscopes

Abstract

A liquid lens based on the electrowetting phenomenon was designed to be cylindrical to minimise dead are. The lens was fabricated with microelectromechanical-system (MEMS) technology using silicon thin film and wafer bonding processes. A multiple dielectric layer comprising Teflon, silicon nitride, and thermal oxide was formed on the cylinder wall. With a change of 11 V-rms in the applied bias, the lens module, including the fabricated liquid lens, showed a focal length change of approximately 166 mm. A capsule endoscope was assembled, including the lens module, and was successfully used to take images of a pig colon at various focal lengths. (C) 2009 The Japan Society of Applied Physics