Directional liquid flow phenomena are widely found in nature on insects and plants, where one-way water collection is driven by the heterogeneous geometry and gradient wettability. Recently, porous materials (e.g., fabrics) allowing transient directional liquid transport have been reported. Such materials were achieved by differential treatment of wettability or lyophilicity across the fabric thickness or combining multilayers of materials with different wettability or lyophilicity as an asymmetric construct. In both cases, liquid tends to transport from lyophobic (e.g. hydrophobic or oleophobic) side to the lyophilic (e.g. hydrophilic or oleophilic) side of the material before the lyophilic side is saturated, but is blocked in the reverse direction. However, the liquid transport rate slows down and the fabrics become heavy and clingy once the outer layer/surface is saturated. In addition, they cannot repel the external liquid contaminants.<br/>Here, we present a conceptually novel design strategy by mimicking the master of sweat regulation—human skin. Human skin is an ideal directional liquid flow material as it excretes liquid sweat and protect the body from external liquid contaminants. In this study, for the first time, we developed a “skin-like” directional liquid transport fabric, which allows continuous one-way water flow and repels external liquid. This is achieved by endowing gradient wettability in spatially distributed porous channels on a predominantly hydrophobic fabric. While these channels serve for one-way liquid flow, the predominantly superhydrophobic nature of the fabric makes it expel the transported liquid or external liquid from the surface. The water transmission rate can be 15 times greater than that of best commercial breathable fabrics. This “skin-like” fabric has great potentials to various applications such as functional clothing, oil-water separation, wound dressing, geotechnical engineering, flexible microfluidics, fuel cell membranes, etc.

“Skin-like” fibrous materials for personal moisture management

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