Bioinspired Dual-Tier Coalescence for Water-Collection Efficiency Enhancement.

Directly harvesting water from the atmosphere could aid in negating the issue of fresh water scarcity, garnering increased research interest in recent years. Typically, atmospheric water collection occurs via three main steps: accumulation, transportation, and collection. Although multiple studies have been published on bioinspired structures with enhanced directional fluid transportation, there is a significant lack of designs for enhancing water droplet coalescence. Long mean times before coalescence result in the re-evaporation of microdroplets, severely impeding the efficiency of atmospheric water collection. Herein, a water accumulator derived from a synergistic combination of inspiration from cacti spines and Tillandsia trichomes has been designed to encourage rapid coalescence. The drip-off volume measured in a fog chamber was found to be 220% that of a flat surface within 15 min, suggesting that improving the coalescence efficiency will be important in the future development of water-collection devices.