Biological and chemical sensing applications based on special wettable surfaces

Special wettable surfaces (SWS, i.e., surfaces with special wettability) are less common in daily life. Some of the frequently studied SWS include those surfaces of homogeneous wettability which are superhydrophobic, superoleophobic, or omniphobic. Additionally, surfaces of patterned wettability which are partially hydrophilic and partially hydrophobic have also been widely investigated. Besides their wide applications in self-cleaning, anti-fogging, water-harvesting, anti-icing, water-oil separation and anticorrosion, the SWS have also been emergingly utilized in biological and chemical sensing in recent years. This review focuses on the SWS-based sensing applications, and classified them into electrical/electrochemical assays, surface-enhanced Raman scattering (SERS) assays, fluorescent/colorimetric assays, and visual assays (i.e. assays based on contact angle). After the main characteristics and performances of these applications were briefly summarized, areas to be improved and direction for future development of this research topic were discussed at the end of the review.