| With the cutting-edge unity of bionic concept and laser micro-nano precision manufacturing technique,this thesis explores the forming mechanism of micro-nano structures on the flat/tapered microdroplets manipulation functional substrates and studies the dynamic process of microdroplets manipulation.Besides,this work reveals the driving effect of laser direct writing superhydrophobic and low-viscosity micropits array planar substrate toward the efficient condensation and rapid self-removal of fogdrop,explains the mechanism of the combination of the tapered curved substrate and the micropits array on the selective and directional collection of microdroplets,the separation and purification of mixed organic liquids.It realizes the flat substrate droplet condensation applications of self-cleaning,anti-deicing,and the fabrication of low surface tension microdroplets pumping and purification devices toward microemulsion separation,biochemical detection.Based on the precise preparation of droplet manipulation flat/tapered substrates,theoretical analysis and experimental comparison are carried out in parallel to carry out research work.This thesis includes the following two aspects.For the contradiction between the high adhesion properties of superhydrophobic substrate in microdroplets condensation and the increasing efficient self-cleaning requirements,based on the relationship between the droplets motion driven by the potential energy from the merged microdroplets and the substrates surficial micro-nano structures,this thesis researches the microdroplets efficient bounce self-removal induced by water condensation on flat substrates.Via the femtosecond laser direct writing strategy,this work illustrates the fabrication of micropits array superhydrophobic surface（with the water contact angle of～165°and the slide angle of～0.6°）toward rapid condensation and efficient removal of water fog,mainly exploring the growth and merging mechanism of microdroplets,conducting the mechanical analysis of drops self-bounce behavior and the structural optimization and design of surficial micropits,illustrating the figural relation between the superhydrophobic property and microdroplets self-removal efficiency.This work propels the development of microdroplet manipulation substrates in the field of self-cleaning,provides solutions for the development of micro-nano multifunctional structure surfaces.In terms of the issue that low surface tension microdrops are difficult to directional delivered and selective collected,inspired by the directional self-transportation of oil droplets on the fish medullary spine surfaces,we constructed a novel fish-spine-like liquid splitter（FSLLS）by employing a precise 3D printing and subsequent femtosecond laser ablation.The liquid splitter enables directional transportation of various microdroplets,with the maximum velocity reaching 265.3 mm s-1.More interestingly,it can spontaneously transport liquids with the surface tension ranging from 15 to 48 m N m-1,achieving an outstanding selectivity of specific liquids.Moreover,the lower the surface tension for the liquid in the surface tension range,the faster the transport speed on the FSLLS.This feature can be attributed to the unique micro-pit structure on the FSLLS surface and its oleophilic properties.The combination of ultrafast directional transportation and peculiar selective ability makes the FSLLS achieve the pumping of microdroplets with lower surface tension.As a proof-of-concept,the separation of the mixed droplets with different surface tensions is demonstrated using the FSLLS and the scalable device.This study offers a new bionic design concept for selective microdroplet pumping devices and opens up an avenue for the separation and extraction of oil droplets in the field of multiphase separation,biomedical analysis,microfluidics,etc. |
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