Construction Of An Open Droplet Array Platform Integrated With Ultrasound And Its Application In Materials Synthesis

The rapid development of microfluidic technology has made it a great success in the field of materials synthesis.Using its multiple advantages such as low consumption,low pollution,highly controllable,tunable and automated,it has successfully achieved the controlled synthesis of many types of materials.And it has also solved the problems of traditional large system synthesis(e.g.,inhomogeneous product size,poor reaction control,etc.)to achieve precise control of parameters such as product morphology,structure and size.Microsystem synthesis is mainly divided into closed droplet microfluidic systems and open droplet systems,among which open systems are gradually coming into the view of researchers due to their ease of manipulation and lack of channel restrictions.However,the microsystem synthesis process must address the challenge of a fast and controlled micro-mixing.Thus,researchers have proposed the concept of a micromixer or micro-mixing platform that can be mainly divided into passive and active micro-mixing.Passive micro-mixing is mainly based on the installation of different shaped microstructures within the microchannels or changing the shape of the microchannels to increase the fluid contact area and reaction time to enhance the micro-mixing effect,which makes passive micro-mixers usually have relatively long reaction paths or complex microchannel structure designs.Thus,researchers have proposed active micro-mixers based on external energy input,which can achieve flexible control as well as fast micro-mixing at short distances.In particular,micro-mixing platforms using acoustic energy as external energy have achieved a boom due to their unique advantages of precise operation,low power consumption,simple structures,good biocompatibility,and high effectiveness.The research work in this thesis combines ultrasound with an open droplet-based array platform to construct a microsystem droplet-based array synthesis platform for the controlled regulation and on-demand preparation of multiple types of materials,and explores the performance of the synthesized materials in multiple fields of application,with the following main research:1.A micropillar-based array platform integrated with ultrasound was developed for non-contact mixing and rapid dispersion of microliter samples.Thanks to the high adhesion performance of PDMS micropillars to aqueous droplets,the micropillar-based array can stably anchor multiple droplets to form an array reaction unit.The introduction of ultrasound is a good solution to the challenge of rapid mixing and dispersion of substances in droplets.The assembly of the platform with a customized circuit board enables on-demand and precise remote adjustment of the micro-mixing effect.The mechanism of this micro-mixing generation is further elucidated by modeling simulation analysis.Finally,rapid mixing and dispersion of microvolume Fe3O4 suspension was successfully achieved.This array droplets platform integrated with ultrasound will have great potential in the fields of precious sample processing,microsystem materials synthesis,and microvolume biosensing.2.Based on the above constructed open droplet array platform and further integrated with reaction temperature and ambient humidity monitoring modules,this droplet-based array microsystem synthesis platform was used to investigate several synthesis parameters which affecting the final morphology of Cu-MOFs.The micropillar-based array can anchor multiple parallelized droplets to build multiple micro-synthesis units,and the integration of the ultrasound module perfectly solves the challenge of rapid and controlled micro-mixing in this dropletbased synthesis platform.Multiple synthesis parameters were efficiently investigated to achieve precise control and guide the on-demand preparation of CuMOFs materials with low reagent consumption.By virtue of the constructed miniaturized database,preliminary prediction of the morphology of Cu-MOFs materials and their size distribution obtained under specific synthesis parameters is realized.The platform is expected to help researchers explore the relationship between the final morphology of multiple types of materials and the input synthesis parameters at low cost,as well as can explore the material growth mechanism,and thus achieve precise control of material preparation and on-demand synthesis.The platform will have great potential for future applications in fully automated and robot-based laboratories.3.With the help of the advantages of the above array droplet synthesis platform,three types of MOFs materials,namely Zn-MOFs,Co-MOFs and Cu-MOFs materials,were synthesized at room temperature by adjusting the type of precursor solution,and the antibacterial properties of the above materials were evaluated and screened at low cost.This array droplet synthesis platform integrated with ultrasound is easily assembled with customized circuit boards to enable one-click batch-on-demand synthesis of multiple types of MOFs materials.The morphology of MOFs materials and their size distribution can be precisely controlled by simply adjusting the ultrasound amplitude and action time.Finally,the above MOFs materials were used as antimicrobial agents,and the size of the inhibition rings of the above MOFs materials were recorded at low cost using the paper diffusion method with Staphylococcus aureus and Escherichia coli as the models.The experimental results showed that the Co-MOFs materials exhibited the best antimicrobial properties,and we further made a preliminary investigation of their antimicrobial mechanisms.This combination of array droplet synthesis and lowcost screening can greatly reduce the cost of research,especially for experimental designs that require multiple parallelization groups.In addition,the platform is also useful for guiding the synthesis of high-performance materials in large quantities.4.By combining ultrasound-assisted array droplet-based synthesis and highthroughput performance screening,an automated and integrated green comprehensive platform was further designed to achieve low-cost and on-demand preparation of multiple types of noble metal@Cu-MOF composites,including AuNPs@Cu-MOF,AgNPs@Cu-MOF,PtNPs@Cu-MOF at room temperature and atmospheric pressure.The array micropillar-based screening platform can further achieve low-cost,high-throughput evaluation and screening of their Ramanenhanced properties.The ultrasound module not only can address the challenge of rapid micro-mixing in microsystems,but also can accelerate the growth rate of the materials,further enhancing the encapsulation of Cu-MOF for multiple types and sizes of noble metal nanoparticles,which achieving high density and high uniformity distribution of nanoparticles in the structure of MOFs.Using this highthroughput green screening platform,full evaluation and screening of the Ramanenhanced performance of the above composites can be easily achieved.And the results show that the AgNPs@Cu-MOF composites have the best Raman-enhanced performance with about 8 times the enhancement effect of AgNPs alone.This automated green comprehensive platform is expected to provide research ideas for on-demand preparation of other types of composites and their high-throughput performance screening.