Design And Experimental Research Of Particle Sorting Microfluidic Chip Based On Surface Acoustic Wave Technology

As one of the greatest discovery in twenty-first Century,the microfluidic chips which is small,portable and have less reagent consumption began to replace the many functions of the conventional medical biochemistry laboratory,such as mixing,reaction,separation and detection,synthesis,cell culture.And the sorting is one of the most core functions.Efficient sorting is of vital importance in the fields of biology,chemistry,diagnostics,therapeutics,material synthesis,and drug development and so on.Based on the wide application of surface acoustic wave?SAW?technology in the field of microfluidics,the multilevel separation technology of particle based on the coupling of hydraulic and acoustic radiation force is proposed,which contain hydrodynamic fractionation technology and acoustic separation technology.Two types of sorting chips are designed and fabricated.By controlling the peak and peak voltage of the load signal,the maximum flow velocity of the main channel and the ratio of the outlet flow rate,two types of sorting chips which is designed and manufactured were used for particle sorting experiment,the main contents of this paper are as follows:The structure and principle of surface acoustic wave devices,piezoelectric substrate and tangential and interdigital transducer?IDT?are summarized.The128°Y-X lithium niobate with double-sided polishing is selected as a piezoelectric substrate.The main parameters of IDT,including finger width,interdigital distance,cross finger logarithm and acoustic aperture are determined preliminarily.The acoustic streaming effect and the force of the particles under the sound field are analyzed.The proposed surface acoustic wave device is analyzed by the simulation software,including modal analysis,harmonic response analysis,transient analysis and the analysis of the influence of the number of IDT's interdigital on SAW energy.The simulation results are consistent with the theoretical analysis basically.The movement of particles in the sound field region is simulated by MATLAB,the optimal parameters to separate the particles are obtained.The motion trajectories of the particles are analyzed only under the action of Stokes force,and the motion law of the particles under different ratio of the outlet flow rate conditions is obtained.The particle motion in the whole microchannel is simulated.The feasibility of particle sorting is verified theoretically,which provides a theoretical basis for subsequent experimental research.Based on the optimized parameters obtained from the simulation,two kinds of particle sorting chips are designed.The surface acoustic wave device and silicon substrate mould are manufactured by micro-fabrication technology.The PDMS microchannel system is manufactured by micro-molding.Then,the surface acoustic wave devices and PDMS microfluidic system are bonded together.After the follow-up treatment,two kinds of structure sorting chips which can be used for the separation experiment are obtained.Two kinds of particle sorting chips presented in this work are used to carry out the separation experiments of various particles.The experimental scheme is designed and the experimental platform is set up.By adjusting the peak-to-peak voltage of the loaded signal,the maximum flow rate of the main channel and the flow ratio,two particle sorting chips are used to research the effect of separation of 1?m,5?m and10?m polystyrene particles?PS particles?.The feasibility of the acoustic separation technique and method proposed in this paper for particle multilevel sorting is verified in the experienment.The experimental results show that the two kinds of structural particle sorting chips have good sorting effect at V_pp=25V and v_max=4mm/s.By adjusting the flow rate ratio,the chip with sequential sorting structure has a better sorting effect than that of direct sorting structure under the condition of A₁=0.2 and A₂=0.5.