Design And Experimental Research Of The Integrated Micromixer Based On Piezoelectric Drive

Micromixing refers to the scientific technology of using micromixers with characteristic scales of tens to hundreds of microns for fluid operation and control.It has the characteristics of rapid response,high efficiency and reliability,process controllability,and low reagent consumption,and it is widely used in biochemical analysis,genetic analysis,cell screening,biomedicine,and chemical synthesis.In order to solve these problems of single function,poor performance,cumbersome operation and low level of integration in the current micromixer,an integrated micromixer based on piezoelectric drive is proposed in this paper.The driving source of the micromixer is the piezoelectric micropump,and the micromixing flow channel is innovatively designed based on the SAR?split-recombine?mixing mechanism.Due to combining the output characteristics of the piezoelectric micropump,and adopting the pulsating mixing mode,the mixing performance is greatly improved,the micromixer has the obvious advantages of excellent performance simple operation,strong initiative and good portability.Finally,The simulation analysis and experimental testing methods are used to prove the excellent mixing ability of the integrated micromixer.The specific research contents of this article are as follows:?1?The micromixing technology and the working mechanism of piezoelectric micropump are studied theoretically.First,the special properties of microfluidics are explained,and the dimensionless constants and control equations that affect the flow of microfluidics are analyzed,then the theoretical basis for improving the mixing effect are obtained,which increases the contact area between the fluids;then,three phase pulsation mixing method is proposed,which possesses an efficient,controllable and stable mixing effect;finally,the working principle of the microfluidic drive device?piezoelectric micropump?is explained,and the piezoelectric vibrator and microvalve are optimized,the effect of micropump output flow,output pressure and cut-off are discussed.?2?The COMSOL software is used to establish the numerical model of the micromixer,and the CFD simulation of the mixing unit and the driving unit are carried out,then the concentration distribution map is obtained;then,with the help of MATLAB software for data processing and calculation analysis,the line chart of the mixing index is obtained.Finally,based on the above results,the mixing performance of the micromixer is comprehensively evaluated,and the structural parameters of the microchannel and the working conditions of the piezoelectric micropump are optimized:microchannel inlet width W=0.30mm,microchannel inlet angle?=60,micropump output flow Q=2.5ml/min and micropump working frequency f=200Hz.At this time,the mixing index reached 0.98,almost completely mixed.?3?The integrated micromixer is designed and manufactured based on the optimized microchannel structure parameters.First,combining the device size with and processing technology,the overall layout design of the micromixer is determined,and the size of the whole machine is determined to be 43mm×55mm×8mm,which meets the design requirements of miniaturization,integration and portability.Then,the appropriate processing materials are selected,and the relevant production process is designed.Finally,based on the PMMA thermocompression bonding process,a micromixer and multiple sets of micropump prototypes are fabricated.?4?The working performance experiment of the piezoelectric micropump and the mixing performance experiment of the micromixer are carried out by using the self-made prototype.First,a performance test platform for piezoelectric micropumps was built.Measured by experiments:when the working voltage is 100V_PP and the working frequency is 200Hz,the output flow rate of the micropump is 4.9ml/min and the output pressure is 15.8kPa,indicating that the piezoelectric micropump designed fully meets the experimental requirements in this paper;then,in the mixing performance experiment of the micromixer,the mixing effect is explored by using the dye tracer method,and the visual characterization is realized by means of computer imaging technology.The comparative analysis of the experimental results with the previous simulation results proves that the micromixer has high mixing performance and application value.