Fog water collection is of great significance to solve the shortage of water resources. How to improve the efficiency of fog water collection has always been a research hotspot.Efficient fog water collection requires both efficient capture and fast transmission.Inspired by nature, the preparation of suitable bionic systems is considered to be an effective way to achieve these two stringent conditions.However, the current biomimetic system has a single structure and low precision, so it cannot achieve efficient fog water collection.
Recently, inspired by wheat and Wheat awn, the biomimetic weinar precision manufacturing team led by Professor Li Guoqiang of Southwest University of Science and Technology constructed a biomimetic wheat and Awn classification system using P SL3D printing technology (Shenzhen Mofang Material Technology Co., LTD., nanoArch® S130), which realized efficient fog water collection.The bionic maowang fog water collection system, which has been optimized and designed, has numerous miniature spinium-oriented collectors distributed on the surface, which expands the effective area of collection, enhances the capture efficiency of fog drops, and breaks through the limitation of droplet transmission under the traditional structure to realize high-speed membrane transmission, greatly improving the transmission speed and collection efficiency.The water mist collection efficiency of this system can reach 5.9g/cm2·h, which is expected to be applied in the field of droplet transmission, drug transportation, cell traction, seawater desalination and other scientific and technological fields.
Figure 1 Structure characteristics of natural wheat awn, fog water collection process and preparation process of bionic wheat awn system.A. Wheat awns catch small water droplets in moist air.B. Wheat awns reverse gravity ultra-fast fog drop transport process.C-e. SEM characterization of the grading structure of natural wheat and awn.Schematic diagram of bionic wheat and awn grading system prepared by P SL 3D Printing system.
FIG. 2 Structural characteristics and evolution of natural and bionic wheat awns.A – C. Statistical curves of structural features of spines and grooves on the surface of natural wheat awns.D-e. Schematic diagram of bionic system of 5 different structural forms.F-g. Characterization of biomimetic systems with different structural forms.H. Schematic diagram of structural evolution of bionic wheat awn with increasing number of microspines.
Important: Wheat and wheat awns capture tiny droplets from moist air as water supplies.This efficient fog water collection capability is mainly derived from the surface of the conical spine, gradient grooves, directional spines integrated grading micro nano system.Through the analysis of the structure characteristics, with the aid of P mu SL printing technology of high precision, freedom to dissembling and reintegration of structure, and according to the structure optimization of building model, the evolution process of the program control the preparation of different structure forms of bionic system, including bionic spinal system (A – spine), bionic groove (A – grooves), bionic tat system (A – minister-designate – 2, 3 A – minister-designate, -, A – minister-designate – 4).
FIG. 3 Fog water collection process of bionic wheat awn with different structure forms.A – e. bionic spine (Ⅰ), bionic grooves (Ⅱ), bionic tat system (Ⅲ Ⅳ Ⅴ) inverse gravity of droplets in a spray environment capture transport process.
FIG. 4 Water mist collection mechanism of bionic wheat and awn.A. c. bionic spine (Ⅰ), bionic grooves (Ⅱ), bionic tat system (Ⅲ Ⅳ Ⅴ) inverse gravity droplets transport distance, speed, volume of statistical graph.D-f. Analysis of fog water collection mechanism of bionic spine, bionic groove and bionic wheat awn system.
Main Points: Through observation in the water mist environment, fog droplets are transported in the form of large droplets on the surface of biomimetic spine and biomimetic groove structure.However, on the surface of the bionic wheat and awn system, no obvious large droplet appears. On the contrary, the droplet is transported by a thin film of water.The transformation of liquid transport mode is mainly affected by surface microstructure.The single-stage biomimetic structure system of the spine and groove is difficult to realize the rapid and efficient capture of fog drops, unable to form a continuous and stable liquid film on the surface, and the captured droplets are easy to be attracted by surrounding droplets and combined into large droplets for transmission.When its volume increases to a certain value, the labrador force produced by the structure cannot continue to drive the droplets and eventually nail to the surface.The bionic wheat awn grading system, due to the addition of numerous micro-spinous oriented collectors on the surface, enhances the ability of fog drops to capture, realizes the rapid wetting process, and forms a continuous and stable liquid film on the surface.In addition, compared with the condensation of other microdroplets on the surface, the time for the microdroplets to slide on the surface of the water film is shorter, so they are more inclined to move along the surface of the water film, which significantly improves the transmission speed and collection efficiency.The experimental results show that the speed of membrane transmission is 40 times higher than that of droplet transmission, and the transmission speed of 3.5 mm/s and the collection efficiency of 5.9 g /cm2·h can be achieved.
The work was published in Chemical Engineering Journal, a world-renowned Journal, with the title “Programmable 3D Printed Wheatawn-like System for High-Performance FogDropCollection”.This work is supported by the National Natural Science Foundation of China and the Science and Technology Department of Sichuan Province.
Paper links: https://www.sciencedirect.com/sc…/ S1385894720311311.
Author: Xiao Lin