Numerical Simulation And Experimental Research Of SAR Micromixer With Two-layer Y-shape Mixing Units

Microfluidic chip is a kind of science and technology that controls the fluid in the microscale space,which has the characteristics of rapid response,high throughput,controllable process and low reagent consumption.As an important part of the microfluidic system,micromixer has a wide range of applications in the fields of chemical synthesis,biochemical analysis,protein folding,nucleic acid sequencing or synthesis.At present,the design and development of micromixers generally have problems such as insufficient mixing effect and poor reliability under low Reynolds numbers.For that,a SAR micromixer with two-layer Y-shape mixing units is proposed in this thesis.The micromixer has excellent mixing performance,low pressure drop,excellent stability and reliability of the prototype.Numerical simulation and experimental verification method are used to prove its excellent mixing performance,and the practical application effect is further confirmed by the silver nanoparticle synthesis experiment.The specific research contents of this thesis are as follows:(1)The theoretical basis and design principles of the micromixer are summarized.Firstly,the basic characteristics of fluid flow under microscale are explained,and the finite element technique and calculus ways of thought are compared and analyzed,which macroscopical grasp for the contents of finite element analysis.Then,the control equations of microfluidic mixing are analyzed,and the mixing principles of micromixer are studied,which lays a foundation for the analysis of the performance of micromixer.Finally,accord to the performance requirements of the micromixer,namely the pressure drop and mixture value,the corresponding optimization objective functions are established.(2)The basic structure of the SAR micromixer with two-layer Y-shape mixing units is proposed,and the structure and performance of the micromixer are fully optimized and analyzed by means of finite element analysis software.Firstly,the geometric model of the micromixer is proposed,and the structural parameters are optimized and analyzed by the objective function established previously.The optimal structural parameters of the micromixer are determined.Then,the influence of Reynolds number on the mixing performance of the micromixer is analyzed using finite element software.Finally,through comparing the performance with the classic micromixers at home and abroad,the excellent mixing performance of the SAR micromixer with two-layer Y-shape mixing units is comprehensively analyzed.(3)Based on the SAR micromixer with two-layer Y-shape mixing units designed in this thesis,the prototype is fabricated,and the mixing performance test is carried out,the actual application effect is analyzed and verified by silver nanoparticle synthesis experiment.Firstly,according to the structural parameters and characteristics of the optimized micromixer,the material and processing method of prototype are reasonably selected,and the prototype is laid out and produced.Then,based on the prepared micromixer prototype,the basic mixing performance of the micromixer is tested by using chemical reagents of C28H30O4 and Na OH,which visually characterized the performance of the micromixer.And qualitative comparison and analysis with the previous simulation results is carried out,which proves the correctness of the simulation results and the excellent performance of the micromixer.Finally,using the chemical reagents such as Ag NO3 and C6H12O6,the application experiment of the micromixer in the field of chemical synthesis is carried out.By adjusting the parameters such as the concentration of the reagents,the use of the protective agent and the inlet flow rate of the micromixer,silver nanoparticles with good morphology,homogeneity and monodispersity are successfully prepared,which also verify the application value of the micromixer in the field of chemical synthesis furtherly.