Research And Application Of Micromixer Design And Mixing Performance Using 3D Printing

Microreactors（mixers）play a crucial role in chemical reactions and mixing processes with their miniaturization and process intensification features.The performance of microreactors（mixers）in terms of mass and heat transfer as well as process control has been extensively investigated in the literature.Compared to conventional batch-type reactors,micromixers offer enhanced mixing due to their characteristic size,which presents significant advantages in various fields such as nanomedicine preparation,catalysis,and bioassay,facilitating the preparation of controllable and generalizable nanoparticles.However,the current micromixers suffer from complex design and manufacture,high prices and the inability to be modified at will,which limits the further application of microreactors（mixers）.By taking accord of this,a multi-channel micromixer was designed using stereolithography 3D printing technology,and a multi-channel vortex micro-mixer was successfully built using commercially available threaded joints,Teflon tubes,and four fluids were strongly mixed in a limited space under the action of a syringe pump.Based on the effective mixing of this mixer,drug-loaded nanoparticles can be produced with small particle sizes.The main research and conclusions of this paper are as follows:（1）Computer-based updates,iterations,and designs,multi-channel micromixer has been successfully constructed using stereolithography 3D printing technology.The first complete generation printed dual-channel micromixer with an inlet channel of 0.5 mm,proving the feasibility of 3D-printed micromixers.The second generation has printed a complete multi-channel micromixer with a 1 mm feature size,a 4 mm diameter chamber and a 1.5 mm height,while the third generation has solved the problem of connecting the inlet to an external syringe pump based on the second generation and tested the practicality of the micromixer.In the fourth generation,the mixer seal was further improved by changing the connection structure of the third-generation micro mixer interface for mixing fluids at high flow rates.In the fourth generation,the mixer seal was further improved by changing the connection structure of the third-generation micromixer interface for mixing fluids at high flow rates.（2）The fluid mixing performance within the multi-channel mixer was first evaluated using the Villermamx-Dushman competition reaction,and then the fluid flow characteristics,substance concentration distribution and mixing mechanism in the multi-channel micromixer were visualized by combining experimental data and CFD simulation.The results indicated a significant decrease in the Reynolds number（Re）from 2127 to 4963,with Xs≈0.0043 for Re=4963,achieving effective mixing.The CFD simulation results showed that for low Re,the center of the chamber had low turbulence intensity.As Re increased,the region of highest turbulent energy shifted toward the center of the chamber.At Reynolds number 4963,the fluid was completely mixed in the mixing chamber,and almost no I₂ was formed.The deflection indices from the CFD simulations were in relatively good agreement with the experimental data.（3）A pH-responsive zeolite imidazolate backbone ZIF-8 complex（TBZ@ZIF-8）nanoparticles were prepared using a printed micromixer to propose a site-specific release system for the fungicide thiabendazole（TBZ）.The results showed that different inlet flow rate ratios had an effect on the morphology of TBZ@ZIF-8.The best morphology was dodecahedral at a flow rate ratio of 1.5:1.5:6.The effect of TBZ@ZIF-8 on particle size and morphology at different residence times（30 s,60 s,120 s）was also investigated.TBZ@ZIF-8 morphology,crystallinity,size,and elements were also characterized.ZIF-8 confers a pH-sensitive behavior to TBZ,and the collapse of the TBZ@ZIF-8 structure and site-specific release of TBZ was triggered by the acid produced by the botrytis cinerea.Furthermore,in vitro,bactericidal assays showed that TBZ@ZIF-8inhibited 75%of bacteria.