Electrowetting optical beam refractor

This paper systematically studies and demonstrates how to lower the operating voltage for an electrowetting optical beam refractor (EOBR). The results indicate that a low operating voltage can be achieved by decreasing the thickness of the dielectric layer and employing a higher dielectric constant, together with reducing the interfacial surface tension between the electrolyte and the surrounding ambient phase. The goal of this study was to explore various approaches to achieving a low operating voltage. First, two kinds of fluoropolymers (Teflon®AF1601 and Cytop®CTL-809M) were utilized to confirm the wettability. Second, Si₃N₄ dielectric layer with different thickness were tested to confirm the thickness and dielectric constant effect. Finally, three different surfactants (sodium dodecyl sulfate (SDS), Triton X100 and Triton X15) were used to confirm the interfacial surface tension effect. In this article, We demonstrate that the contact angle of water can change as much as 80° in a dodecane/water/Cytop®/Si₃N₄ system (containing 1% SDS) with an applied voltage as low as 14 V; furthermore, switchable apex angles of ≃± 20° and deflection of a beam passing through the meniscus of EOBR are presented.