Durability Enhancement of a Microelectromechanical System-Based Liquid Droplet Lens

Abstract

In this paper, we propose methods to enhance the durability of a microelectromechanical system (MEMS)-based liquid droplet lens driven by electrowetting. The enhanced durability of the lens is achieved through not only improvement in quality of dielectric layer for electrowetting by minimizing concentration of coarse pinholes, but also mitigation of physical and electrostatic stresses by reforming lens cavity. Silicon dioxide layer is deposited using plasma enhanced chemical vapor deposition, splitting the process into several steps to minimize the pinhole concentration in the oxide layer. And the stresses-reduced cavity in a form of overturned tetra-angular truncated pyramid with rounded corners, which is based on simulated results, is proposed and realized using silicon wet etching processes combined into anisotropic and isotropic etching.

Temperature effects on dielectric liquid lenses

“…Adaptive liquid lenses provide innovative and exciting opportunities to enhance the optical performance, accuracy, throughput, and reliability while reducing overall cost in machine vision, medical, and optical communication systems [1][2][3][4][5][6][7][8][9]. Various approaches have been proposed to achieve adaptive focus [10][11][12][13][14]. Among them, electrowetting [15][16][17] and dielectrophoretic effect [18][19][20][21][22][23] are considered as the most attractive ones in terms of compactness and simple electrical actuation.…”

“…As a result, the focal length can be tuned. Various dielectric liquid lenses have been demonstrated and their characteristics studied [10,11]. Most of them are operated at room temperature rather than an elevated temperature.…”

Variable-focus Liquid Lens Based on a Laterally-integrated Thermopneumatic Actuator

“…Diverse driving forces for focal-length control have been introduced by numerous research groups. For instance, an electrowetting-based lens [6][7][8], dielectrically actuated lens [9,10], fluidic-pressure-based lens [11][12][13][14][15], liquid-crystal lens [16][17][18], and polymer-gel lens [19] have been reported. Both electrowetting-based lenses and dielectrically actuated lenses use external voltage to control the shape of a refractive liquid, and they exhibit fast responses without moving mechanical parts for focal-length modulation.…”

Design and fabrication of PMMA-micromachined fluid lens based on electromagnetic actuation on PMMA–PDMS bonded membrane

“…Due to their simple principle of operation and a wide choice of fluids, hydraulic pressure-based fluid lenses [4][5][6][7][8][9][10][11] provide comparatively higher focusing ranges and faster responses than competitive mechanisms, e.g. electrowetting [12,13], dielectrophoresis [14,15] and liquid crystal [16,17]. Hydraulic pressure-based fluid lenses make use of the deformation of an elastomeric membrane integrated with a chamber filled with a refractive fluid.…”