Research On Bioinspired Wheat-awn Fog-Collecting Multilevel Device And Multimodal Fog Drop Transport Mechanism

With the rapid population expansion and environmental pollution caused by industrial processes,the shortage of freshwater resources is seriously threatening the ecosystem and human survival.Water mist is common in desert,mountain and coastal areas where fresh water resources are scarce.The water content can reach 0.5 g·m^-3,regarded as a kind of environmental resource to alleviate the water shortage.In view of this,researchers have employed the bionic design concept to develop a variety of bionic fog collection devices.However,due to the harsh conditions and preparation process required for water mist collection,the current fog collection devices are difficult to play an efficient water mist collection.In response to the existing problems,this work successfully designs and realizes the fabraction of high-efficiency fog collecting device by means of precision 3D printing.First,based on the phenomenon that the wheat awns at the outer glumes of wheat ears can capture tiny droplets when exposed to moist air,and realize the directional transportation toward the ears,the surface structure of the wheat awns is analyzed,and it is found that the wheat awns is a multi-scale hierarchical structure consisting of a tapered spine,directional thorns,gradient grooves.Besides,inspired by the wheat awn,by using precision 3D printing technology,we developed a biinspired wheat awn multi-stage fog collection system.By adjusting the key parameters of the structure（the cone angle of the spine,the tilt angle of the spindles,the arrangement and configuration of the spindles,and the number of gradient changes of the grooves）,the omni-directional directional directional transportation,as well as the multi-mode transportation mode of drop transportation and membrane transportation are realized.The film transport mode allows the droplets to be transported in the form of a water film,which significantly increases the transport speed of the droplets.The transport velocity is up to 3.5 mm/s.Combined with the hydrophilic substrate to form a device,it can achieve a fog collection efficiency of 5.9 g/cm²·h.Finally,based on the theory of interfacial wetting and capillary,a mechanical model of multi-level structure of wheat awn for efficient water mist collection is established.An integrated system for large-scale water mist collection and application is designed,which has great application prospects in desert,mountain and other areas.Fog not only contains abundant micro water droplets,but also carries mechanical energy.In order to collect droplets and energy at the same time,a hydrophilic copper cone and Janus environment water collecting integrated device was prepared by using conical copper as water mist collecting end and electrode end and copper sheet as plane electrode.The device realized droplet collection,unidirectional penetration and micro energy collection.