Achieving ultralong directional liquid transportation spontaneously with a high velocity

Abstract

Due to its appeal in the merit of no external energy input, the passive surface is widely considered to be an ideal platform for liquid transportation. Despite the considerable progress attained, achieving long-range and high-speed liquid transport on a passive surface remains challenging due to several inherent difficulties, such as the insufficient driving force and undesired energy dissipation. Here, we overcome these limitations by proposing a cellular design of wettability pattern (CWP). This CWP is composed of cells with a wettability gradient and a cascaded super-hydrophilic divergent channel, where the cells are seamlessly interconnected with each other through the channel. Utilizing the enhanced driving force and reduced energy dissipation endowed by the special wetting and geometrical design, the proposed CWP can spontaneously transport a water droplet over a distance of 100 mm, the longest distance ever reported, with a high average velocity of ∼92 mm s⁻¹. We demonstrate experimentally and theoretically that the transport distance can be further enhanced by tailoring the wettability gradient. Using a predefined CWP, we also achieve on-demand liquid manipulation. We envision that our cellular design will find numerous applications in materials science, interfacial chemistry, and biomedical research.