Programmable 3D printed wheat awn-like system for high-performance fogdrop collection

Abstract

Highly-performance fogdrop collection is of great practical importance in addressing the worldwide water shortages, especially in arid regions. Although great progresses have been made to solve this problem, there still are challenges in developing high-performance fogdrop collecting systems to satisfy efficient fogdrop capturing and fast transport simultaneously, which are two critical factors that determine the collection efficiency. The well-evolved water-collecting capacity of creatures that adapt to the harsh environment provides a great inspiration for the design of efficient collection systems. Here, inspired by the unique hierarchical structures and the excellent fogdrop collection ability of wheat awn, artificial awn-like hierarchical systems are developed via a precision 3D printing strategy which exhibit excellent fogdrop capture and fast transport. The presence of hierarchical structure composed of conical spine, gradient microgrooves, and oriented thorns enables the fogdrop collection to transform from dropwise mode on the thorns to filmwise one on the spine. Furthermore, the collection efficiency of such a bioinspired system is 5.90 g/cm−2·h, which is higher than individual ones and other bioinspired systems. Through the model of structure–function relationship, the mechanisms of diverse collecting behaviors are explored to address the origin of highly-performance collection. This work opens up new avenues to design systems and devices for dramatic fogdrop collection enhancement.