Electrowetting on liquid-infused film (EWOLF): Complete reversibility and controlled droplet oscillation suppression for fast optical imaging

TL;DR

This paper introduces EWOLF, a liquid-infused film-based electrowetting technique that achieves complete droplet reversibility and oscillation control, enhancing optical imaging applications.

Contribution

The study presents a novel EWOLF configuration enabling full reversibility and tunable response, overcoming limitations of traditional EWOD in droplet manipulation.

Findings

EWOLF allows complete droplet reversibility.

Suppresses droplet oscillation and contact line pinning.

Enables fast optical focusing using liquid lens.

Abstract

Electrowetting on dielectric (EWOD) has emerged as a powerful tool to electrically manipulate tiny individual droplets in a controlled manner. Despite tremendous progress over the past two decades, current EWOD operating in ambient conditions has limited functionalities posing challenges for its applications, including electronic display, energy generation, and microfluidic systems. Here, we demonstrate a new paradigm of electrowetting on liquid-infused film (EWOLF) that allows for complete reversibility and tunable transient response simultaneously. We determine that these functionalities in EWOLF are attributed to its novel configuration, which allows for the formation of viscous liquid-liquid interfaces as well as additional wetting ridges, thereby suppressing the contact line pinning and severe droplet oscillation encountered in the conventional EWOD. Finally, by harnessing these functionalities demonstrated in EWOLF, we also explore its application as liquid lens for fast optical focusing.