Bioinspired Nanostructured Surfaces for On-Demand Bubble Transportation.

The maneuver of small bubbles in a programmed way will advance numerous processes, including gas evolution reaction and aeration. Unlike in-air droplets, rapidly rising bubbles in liquid medium can hardly be steered through interaction with solid substrates, causing difficulties in maneuvering bubbles. We pattern and lubricate nanoporous substrates with regions of contrasting wettability that is similar to the back of Namib desert beetles and subsequently immerse the lubricated surface underwater to spontaneously form spatially patterned Nepenthes-inspired slippery surfaces after the dewetting of lubricants. As a result, bubbles are confined on lubricant-infused surfaces, with their high mobility well preserved. The interfacial states of attached bubbles are analyzed, and their dynamic sliding velocities are quantified. Using the lubricated patterned surfaces, we further demonstrate the predefined motion of bubbles driven by buoyancy at a small tiling angle, as well as a self-propulsion of bubbles driven by surface tension force at a tilting angle of 0°, respectively. The spatially lubricated surfaces simplify gas handling in liquid medium and have potential applications in fields where bubble handling is crucial.