Design And Experimental Study Of The Integrated Micromixer Driven By Valveless Piezoelectric Pump

As a new type of active micromixing,there is a growing concern of domestic and foreign scholars about the research and application of pulsed micromixing method based on piezoelectric valveless pump in the microfluidic system.The research not only has great academic significance,also has important application value in the field of Chip Integrated system,Micro Total Analytical system(?-TAS)and other fields.This paper proposes and designs an integrated micromixer driven by the valveless piezoelectric pump.It integrates the drive source valveless piezoelectric pump and Y type micromixing channel in a PDMS chip.By means of pulsating drive for integrated micromixer,it can realize the precise delivery and controllable mixing for solutions contained with particles.Specific research contents are as follows:Based on the classical expansion / contraction port valveless pump,a new type of valveless piezoelectric pump with variable height and embedded obstacles is proposed.By means of the flow characteristic analysis about the new pump,the feasibility of the new valveless pump is theoretically proved.The structure parameters of the valveless pump are analyzed and researched systematically by using the finite element analysis method,the equivalent circuit model and experimental test method.The optimal structure parameters of the new pump were determined: Obstacle angle of 15 degrees,the minimum distance of 0.12 mm,and the pump cavity depth of 0.15 mm,the channel height ratio of 5.The experimental results showed that the pump flow rate is approximately 0.87ml/min and the output pressure reaches 0.3kPa under the driving voltage of 70 V,frequency of 270 Hz.Various factors affecting microflow are analysisd.According to the design and manufacture of valveless pump and micromixer,the influence of wall slip on the flow and mixing of the solution is emphatically investigated.Based on the wall slip effect,the FEA is used to optimize the structure and control parameters of the Y type micromixing channel.Simulation results show that the degree of the export mixing approximately reaches 0.933 under the channel section size of 0.2mm×0.2mm,entrance angle of 90 degrees,the driving frequency of 100 Hz,the entrance flow of0.7ml/min.The effect of wall slip can not only reduce the fluid resistance,ensuring the smooth flow of solution,also effectively improve the performance of the mixed solution.The structural integration of the valveless pump and the Y type micromixing channel are designed,and the fabrication technology of integrated micromixer is studied.The integrated micromixer prototype which selects the PDMS as the main material is fabricated by the method of molding and encapsulation.Through using the integrated micromixer for pulse injection and fluorescent particle mixing experiments and adjusting the control parameters,the pulse phenomena in the mixing channel and the velocity image of the fluorescent particles are observed.The experimental results show that the integrated micromixer driven by valveless pump can form a pulsation phenomenon.There is no obvious agglomeration phenomenon of fluorescent particles in the PDMS channel and the wall surface which validates the influence of wall slip effect,and the velocity distribution of fluorescent particles is more uniform at the outlet.Through the systematic mixing experiment,it is feasible to use the integrated micromixer driven by valveless piezoelectric pump to transport and mix solutions contained with particles.