High-Efficient Fog Harvest from a Synergistic Effect of Coupling Hierarchical Structures

Abstract

Fog harvesting is an important method to solve the water shortage in arid and semi-arid areas by collecting water from air. Improving fog harvesting efficiency is still a big challenge to be overcome. Herein, under the inspiration of natural creatures, a novel harvesting structure that couples a hierarchical microchannel (HMC) needle with the Janus membrane by taking a conical pore as their junction is proposed. Such an HMC-conical pore-Janus membrane system can improve the harvesting efficiency by regulation of liquid behavior in the whole fog harvesting process involving droplet capture from air, high speed transport on the microchannel, and droplet detachment from Janus. The synergistic effects of the hierarchical channel-conical pore-Janus structure are exploited in terms of capture, transport, and detachment capabilities, and their underlying mechanism to enhance fog harvesting efficiency is built. Compared with the traditional harvesting structure, the proposed hierarchical channel-conical-Janus coupling mode was demonstrated to improve fog harvesting efficiency by 90%. Such a coupled system has potential applications in efficient fog harvesting systems, microfluidic devices, and liquid manipulation.

Femtosecond-laser-patterned origami Janus membrane toward enhanced water fog harvesting

“…Therefore, there is an urgent need to develop highly efficient and eco-friendly approaches to freshwater harvesting. [1][2][3] Researchers have reported diverse materials/ methods for freshwater collection to meet a wide variety of usage scenarios such as osmotic membranes, 4 sewage treatment, 5 desalination, 6 fog collection, 7 etc. It should be emphasized that water fog is composed of a large number of tiny water droplets suspended in the atmosphere, which constitutes approximately 10% of freshwater resources on Earth.…”

“…Inspired by the excellent water collection and drainage properties on corrugated cardboard-shaped structures from traditional Chinese roof tile architectures, we adopted an origami craft to fabricate a three-dimensional (3D) O-P-Janus membrane via selective femtosecond laser processing and compression molding of 3D printing technology, 33,34 to create asymmetric wettability gradients across the thickness as well as on the bottom of porous copper foam. Compared to the planar fully-ablated Janus membrane, this O-P-Janus membrane with optimized rectangular patterns exhibited an exceptional WCR of up to ∼267%.…”

Origami-like 3D Fog Water Harvestor with Hybrid Wettability for Efficient Fog Harvesting

“…At present, people in many countries and regions live in an environment with limited freshwater resources. − The search for environmentally friendly and efficient ways to obtain fresh water has attracted worldwide attention. Population increases have led to a sharp reduction in water resources per capita, further exacerbating the overall water shortage . Therefore, collecting water resources in fog has also become a breakthrough to solve the hidden danger of water shortage in some arid areas.…”

“…Population increases have led to a sharp reduction in water resources per capita, further exacerbating the overall water shortage. 4 Therefore, collecting water resources in fog has also become a breakthrough to solve the hidden danger of water shortage in some arid areas. However, it is still a challenge to develop special structures or surfaces that can efficiently collect freshwater resources from fog.…”

Bioinspired cone structures with helical micro-grooves for fast liquid transport and efficient fog collection

“…Directional liquid transport has been discovered on many natural creature surfaces with unique microstructures, such as the backs of desert beetles with patterned hydrophobic bulges, 1 spider silks with periodic spindle-knots and joints, 2 cactus spines in conical shape and with gradient grooves 3 and Sarracenia trichomes with dual-leveled micro-grooves. 4 Inspired by these intriguing structures, various articial systems capable of propelling liquids directionally have been developed in the past few decades, showing applications in fog-collection, [5][6][7] underwater bubble manipulating, 8,9 oil/water separation [10][11][12] and microuidics. 13,14 In particular, the cactus spine integrates elements facilitating liquid transport-conical shape, gradient of surface free energy, and aligned grooves, making it an ideal model for biomimetic designs capable of driving liquids to move directionally.…”