Flexible hemline-shaped microfibers for liquid transport

Directional liquid transport is important in both fundamental studies and industrial applications. Most existing strategies rely on the use of predesigned surfaces with sophisticated microstructures that limit the versatility and universality of the liquid transport. Here we present a platform for liquid transport based on flexible microfluidic-derived fibers with hemline-shaped cross-sections. These microfibers have periodic parallel microcavities along the axial direction, with sharp edges and wedge corners that enable unilateral pinning and capillary rise of liquids. This structure enables directional liquid transport along hydrophilic substrates with the use of a single fiber. Alternatively, a pair of fibers enables directional liquid transport along hydrophobic substrates or even without any additional substrate; the directional transport behavior applies to a wide range of liquids. We demonstrate the use of these fibers in open microfluidics, water extraction and liquid transport along arbitrary three-dimensional paths. Our platform provides a facile and universal solution for directional liquid transport in a range of different scenarios. A flexible hemline-shaped microfiber featuring periodic parallel microcavities with sharp edges and wedges was developed using microfluidics to achieve unidirectional liquid transport along arbitrary pathways.