Mimicked Trees for Spatial Microfluidic Solar Evaporation

The lack of freshwater is becoming an increasingly urgent problem, and clean water production with green energy is becoming a hot topic. Among these, mimicked transpiration for water treatment enabled with solar energy is attracting more and more interest. In this work, we design unique microchannels inspired by leaf veins in nature. We experimentally observe the unique microfludic phenomena exhibited during liquid transport inside the mimicked microchannels, and the underlying mechanisms of the microfluidic performance of the mimicked microchannels are also revealed. Moreover, a type of mimicked leaf integrating "veins" for fluid transport and "stomata" for solar evaporation is designed. Our mimicked leaves achieve rapid liquid transport, when the light intensity is 1 sun, the maximum evaporation rate is 1.85 kg m^-2 h^-1, and the photothermal conversion efficiency is higher than 92%. In addition, with the rapid liquid transport capability of our mimicked leaves, we innovatively design a mimicked tree for spatial solar evaporation, exhibiting an evaporation rate of 1.52 kg m^-2 h^-1 with a light intensity of 1 sun. Our mimicked trees promise the microfluidics-powered, large-scale and multidirectional transportation of water, as well as excellent spatial evaporation of water.