Droplet Removal by Capillary Lifting

TL;DR

This paper explores a novel method for removing liquid droplets from surfaces using capillary lifting with an immiscible liquid, revealing how interfacial tensions and contact angles influence dewetting efficiency.

Contribution

It introduces a theoretical and experimental framework for droplet removal via capillary lifting, highlighting the role of interfacial tension and contact angle manipulation, differing from traditional surfactant-based methods.

Findings

Droplet removal efficiency depends on contact angle and interfacial tensions.

High interfacial tension in the working liquid enhances dewetting.

The method offers a sustainable alternative to surfactant-based cleaning.

Abstract

The removal of liquid droplets from solid surfaces is central to cleaning, coatings and oil recovery. Here we investigate liquid droplets capillary lifted by an immiscible working liquid. The rising working liquid triggers the formation of a capillary bridge between the solid and the air interface, which can lead to full, partial, or no droplet dewetting. Our theoretical model predicts, and experiments confirm, that the effectiveness of droplet removal can be tuned by manipulating the droplet contact angle with the solid and the interfacial tensions at play. Significantly, dewetting can be enhanced by employing working liquids with high interfacial tension, in contrast to common surface cleaning strategies where surfactants are used to reduce interfacial tension. Our findings can open new avenues for droplet manipulation with reduced resources and more sustainable environmental impact.