The 9th International Conference on Surface Engineering (ICSE 2024)

The wettability changes and directional diffusion of bubbles/droplets on functional surfaces have become a hot research topic, with broad application prospects in microfluidic chips, microchemical reactions, precision medical equipment, gas collection, and antibacterial fields. However, this research still faces multiple challenges, including short transport distances, slow driving speeds, difficulty in dynamically regulating motion states, and complex preparation methods. Here, inspired by the needle-like spines of cactus and the super-slipping orbit of Nepenthes, gradient structures with different wetting characteristics were constructed, a temperature-responsive track was prepared to achieve the switch between water spreading and pinning; utilizing hydrophobic-oleophilic properties to achieve the adsorption and transport of underwater oil droplets, with an oil-water separation efficiency of up to 99.9%; capturing underwater bubbles using hydrophobic-hydrophilic properties of conical microcolumns, and building an integrated device for bubble capture, transportation, and collection with a collection efficiency of~90%. Inspired from the water collection ability of the spider silk, a Janus membrane with spindle knots could separate oil-in-water and water-in-oil emulsions with ultra-high efficiency. The revelation of the influence of biomimetic structures on the directional transport of bubbles/droplets in different media will provide a theoretical basis for fluid multiphase separation, bubble capture, and patterned design of microfluidic chips.

gradient structures,oil-water separation,adsorption,transport