Wettability Contrast Surfaces: Fabrication and Applications
A. Peethan, J. Lawrence and S.D. George
Nature-inspired fabrication of surfaces with special wettability or wettability contrast is rapidly emerging as an area of intense research activity in materials research. This interdisciplinary research area of bio-mimicking naturally occurring surfaces to obtain self-cleaning, directional transport of liquids, droplet splitting, etc., have been finding an increased usage in fields such as solar cells, bio-sensing, water harvesting. This review discusses different wettability models that explain the spreading of a droplet on a solid surface, depending on the surface morphological and chemical structure. Further, we focus on the understanding of wettability contrast surfaces, its fabrication, and emerging applications in diverse areas. As elucidated here, an advancement in chemical as well as physical routes to fabricate the hierarchical structures enabled the creation of wettability contrast surfaces that exhibit contrast between superhydrophobic to superhydrophilic. In addition, the applications of desert beetle inspired wettability contrast surfaces for fog/water harvesting and other applications of surfaces with contrast wettability in the areas of microarrays, biomedical applications, and other emerging fields are reviewed in detail.
Keywords: Bio-mimicking, Wettability, Superhydrophobicity, Superhydrophilicity, Water harvesting, Fog harvesting, Droplet assays