Cross-hatch textured cone enables Dual-Mode water transport and collection

Abstract

Spontaneous droplet transport has broad application prospects in water collection, whereas droplet self-transport is still limited by slow transport velocity, short distance, and poor integrity. Here, a novel cross-hatch textured cone (CHTC) with gradient microchannels and circular grooves is proposed to realize ultrafast long-distance self-transport of multi-scale droplets, whose self-transport velocity is 1–4 orders of magnitude faster than natural or biomimetic structures with single curvature gradient. The CHTC triggers two modes of fluid transport: Droplet transport by Laplace pressure difference and capillary suction pressure-induced fluid transfer in microchannels on cone surfaces. The gradient microchannels connected by circular grooves ensure that the residual water layer and the water droplet detained on the CHTC can still be spontaneously transported to the base to eventually realize the entire droplet transport. A theoretical formula on the suction pressure is established to elucidate the driving force responsible for the self-transport of both detained water droplet and the residual water layer. The fog collection efficiency of the CHTC is about twice as high as the cone without microchannels. These findings will open the door to achieving ultrafast long-distance and lossless self-transport of droplets and will provide tremendous inspiration for the design of the water collection apparatus.