Overcoming Long-Range Unidirectional Transport of Underwater Bubbles on Laser-Textured Single-Layer Superaerophobic Dual-Rail Arrays.

Understanding the behavior of gas bubbles in aqueous media has been a hot topic because of their vital roles in both scientific research and industrial applications. Wettability gradient force and Laplace pressure are two typical characteristics of bubble transport. However, most work about bubble transport is limited to a short distance. Therefore, we took inspiration from the structure of the Nepenthes pitcher and prepared superaerophobic dual-rail arrays (SDRA). Upon SDRA, with this structure of a uniform distribution of superaerophobic and superaerophilic zones, bubbles can be transported over long distances on the structure's surface. The underlying principle is that gas bubbles tend to spread out on the superaerophilic region until they make contact with the asymmetric superaerophobic barriers. An asymmetric spreading resistance force is generated, which is attributed to the different lengths of the three-phase contact line (TCL) between gas bubbles and superaerophobic barriers. In addition, diverse parameters are quantified to investigate the critical transport state between unidirection and bidirection. Under the function of SDRA, the structure surface can realize bubble collection. The transporter as well as the light-control-light shutter is also successfully deployed. The present study will inspire people to develop innovative strategies to effectively manipulate gas bubbles in practical applications.