Droplet removal by capillary lifting

The removal of liquid droplets from solid surfaces is central to cleaning, coatings and oil recovery. While dewetting in binary fluid systems has been widely studied, the mechanisms governing dewetting in ternary systems involving an immiscible working liquid remain poorly understood. Here we show that a rising working liquid can capillary lift droplets into bridges extending from the solid surface to the air interface, leading to full, partial, or no droplet removal. 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 in the system. 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 suggest new avenues for droplet manipulation, especially if concerned with reduced resources and a more sustainable environmental impact.