Floating Electrode Electrowetting on Hydrophobic Dielectric with an SiO2 Layer

TL;DR

This paper demonstrates floating electrode electrowetting on a hydrophobic dielectric with an SiO2 layer, enabling charge retention and a memory effect, which could advance electrowetting device development.

Contribution

The introduction of a thermally-grown SiO2 layer under Cytop enables charge retention and memory effects in floating electrode electrowetting, offering a new device configuration.

Findings

Charge separation causes electrowetting without direct electrical contact.

SiO2 layer prevents charge leakage, enabling memory effects.

Floating electrowetting offers an alternative device architecture.

Abstract

Floating electrode electrowetting is caused by dc voltage applied to a liquid droplet on the Cytop surface, without electrical connection to the substrate. The effect is caused by the charge separation in the floating electrode. A highly-resistive thermally-grown SiO2 layer underneath the Cytop enables the droplet to hold charges without leakage, which is the key contribution. Electrowetting with an SiO2 layer shows a memory effect, where the wetting angle stays the same after the auxiliary electrode is removed from the droplet in both conventional and floating electrode electrowetting. Floating electrode electrowetting provides an alternative configuration for developing advanced electrowetting-based devices.