Light-Caused Droplet Bouncing from a Cavity Trap-Assisted Superhydrophobic Surface.

Actuating droplet bouncing from a rigid surface is of considerable interest for potential applications, ranging from novel droplet microfluidics to self-cleaning and anti-icing. The photothermal effect and the accompanying phase change initiate a route for manipulating the tiny amount of liquid. In this work, we present a concept of droplet bouncing from a cavity trap-assisted superhydrophobic platform actuated by the photothermal effect-induced intense evaporation, which enables the purposeful manipulation of the droplet bouncing. It is demonstrated that such a design limits the vapor transport so that the vapor pressure under the droplet is considerably improved to overcome the gravity and liquid-solid adhesion force, leading to the droplet bouncing. Moreover, experimental results indicate that droplet bouncing behaviors can be easily tuned by simply adjusting the cavity dimension and the input laser power. This work provides a new method for the manipulation of droplet bouncing, presenting promising perspectives for future possible applications.