Design And Experimental Research Of The Integrated Micromixer Based On PMMA Bonding Process

Piezoelectric driving pulse mixing,which is a new drive mode of microfluidics,is receiving wide attention and study of scholars at home and abroad.It not only has important academic significance,but also possesses significant application value in several fields such as Medical Testing,Organic Synthesis,Precious Nanoparticles Preparation,etc.This paper puts forward an integrated micromixer based on PMMA bonding technology,which represents a new application of piezoelectric driving.The contact area of the two solutions has been increased by the pulse injection of the piezoelectric micro-pump toward microfluidics.What's more,the micro-channels can be processed into dimensional complex structure based on PMMA bonding technology,thus the turbulent mixing of the two kinds of solutions can be formed in many places.The combination of the two hybrid methods improves the mixing efficiency of microfluidics and achieves the quick-mixing of the solutions.The author chooses a kind of slicing layer design and conducts an experiment on the organic solutions of the thermal bonding according to the nature of PMMA.Then ethanol solution is determined to be the organic solution of the bonding.In addition,the author also conducts a large number of experiments on the important factors such as temperature and pressure,which have big influences on the bonding property.The result of the experiment shows that it reveals the best effects when the pressure is about 1-1.5 Mpa and the temperature is between 80? and 90°?after ethanol solution is taken as the organic solution.Hence,this paper chooses(1.5Mpa,80?)as the final bonding parameter for the integrated Micromixer.By comparing the output pressure and the output flow of the single and double cavity of piezoelectric micro-pump,the author chooses the double cavity series of piezoelectric micro-pump,which possesses a high performance quality as the driving source of this commingles.The author carries on the theoretical design on each parameters of double cavity of piezoelectric micro-pump respectively,a high-powered double cavity series of piezoelectric micro-pump is obtained.The cross sectional area of the two inlet port is preliminarily confirmed as 0.6mm×0.6mm along with the Y shape of channel structure with an intersection angle at 120°.Then the author makes simulated analysis of the mixing effect of the solutions in flat dc and in multi-corner dc by using MATLAB and ANSYS respectively.The result shows that the mixing effect of fluid has close relationship with Reynolds number.The solution needs a long passageway only on the condition that it diffuses to a completely mixed level while the corner can quicken the mixing of microfluidics.Based on the new bonding technology,which has been discussed in this paper,the author designs a multi-corner and screw type of the three dimensional flow,and the overall dimensions of the integrated micromixer are determined to be 70 mm × 30 mm × 7.2mm.Based on the pulse mixing mode,the author makes a theoretical analysis toward conditions that produce the pulse effect.The result shows that the pulse conditions which can produce the crescent shape of two kinds of solutions are closely related to the cross sectional area of the passageway,the density of the fluid,the intersection angle of Y shape passageway.The ideal ripple effect can not be formed either the injected solution is too little or too much.On the contrary,the change of frequency or the change of one-off injection flow rate can form the ideal ripple effect.Also,the author makes a simulated analysis toward the entrance of Y shape and the partial passive passageway.The result represents that it forms an ideal ripple effect when the entrance velocity is 0.05m/s,the output flow is 1ml/min,the incoming frequency is 50 Hz,and the width of cross section is 0.2mm.According to the result of this simulated analysis,the cross sectional area of Y shape entry port is determined to be 0.2mm× 0.6mm,and the cross sectional area of other ports is identified to be 0.6mm× 0.6mm.The overall dimensions of the whole micromixer are optimized from the original 70mm× 35 mm × 7.2mm to 50mm× 35 mm × 7.2mm.The author puts the integrated micromixer into the access to water along with different viscosity of water-glycerin solution to conduct the output perrformance test.The result of the test reveals that the maximum output flow of this commingler toward water is 7.3ml/min,and the maximum output flow toward water-glycerin with the viscosity of 10 mPa.s is 2.3ml/min.Then the author conducts the ripple effect test by using water and water-glycerin solution.The result of the experiment shows that the entrance of Y shape can produce obvious ripple effect when the frequency is 50 Hz and the output flow is 1ml/min.What's more,the experiment shows that the good or bad quality of the ripple effect in this commingles has small relationship with the viscosity of solution whereas it has an evident relationship with the size of the outflow.Finally,the author conducts the mixing effect test by using water-glycerin solution with fluorescent particles.The result reveals that the passageway with multi-corners is beneficial for the mixing of solutions and the effect with a pulse mixer can promote the process of mixing,which is much higher than that without a ripple effect.