Observation of contact angle hysteresis due to inhomogeneous electric fields

TL;DR

This paper reports the first observation of electrowetting-induced contact angle hysteresis, revealing how inhomogeneous electric fields can dynamically control surface wettability, with implications for creating switchable sticky surfaces.

Contribution

It introduces the experimental observation and theoretical analysis of electrowetting hysteresis, expanding understanding of electric field effects on contact angle hysteresis.

Findings

Electrowetting can induce static contact angle hysteresis.

Electric fields alter the surface free-energy landscape.

Potential for creating switchable, sticky-on-demand surfaces.

Abstract

Static contact angle hysteresis (CAH) is widely attributed to surface roughness and chemical contamination. In the latter case, chemical defects create free-energy barriers that prevent the contact line motion. Electrowetting studies have demonstrated the similar ability of electric fields to alter the surface free-energy landscape. Yet, the increase of apparent static CAH by electric fields remains unseen. Here, we report the observation and theoretical analysis of electrowetting hysteresis. This phenomenon enables the continuous and dynamic control of CAH, not only for fundamental studies but also to manufacture sticky-on-demand surfaces for sample collection.