Facile Fabrication of Extremely Wet Surface Harnessing 5nm-thick Gallium Oxide on Liquid Metal

Here, we propose to design, develop, and understand the biomimetic superhydrophobic-superhydrophilic surface harnessing (a) the wetting/dewetting of Nano-textured conductive surface patterns and (b) interfacial chemical reactivity of Gallium alloys. Superhydrophobic-superhydrophilic patterns on the same substrate provide an unprecedented opportunity to precisely control the geometry and shape of liquids, mostly water. These surfaces are well-sought in applications related to energy, water, health care, and even daily activities. Extreme-wetting transition surfaces are crucial to separate oil from water, water treatment, fog harvesting, self-cleaning, blood-plasma separation, cell-biology, and lab-on-chip applications. Also, in nature, superhydrophobic surfaces are used for the reduction of CO₂ uptake, which is necessary for photosynthesis. Superhydrophilic surfaces are proven successful for the separation of peptides. Superhydrophobicity-superhydrophilicity is essential for proteins, cells, and bacteria as well. In the literature, numerous complex methods have been reported to generate such surfaces. Most of those successful methods are energy-intensive and need many well-controlled processing steps. We, therefore, propose a simple two-step process that will enable the design and development of superhydrophobic-super hydrophilic patterns on the same substrate. Our method utilizes the Nano-textured native oxide (Gallium Oxide, Ga₂O₃) of Gallium and its interfacial amphoteric chemical reactivity (i.e., can be chemically removed by base and acid). We will also demonstrate open-ended microfluidic principles (e.g., mixing, and dilution) utilizing the current method.