Research On Acoustic Field Local Focusing Technology Based On Acoustic Metamaterials

As an emerging technology formed by the intersection of physics,microelectronics,biomedical engineering and other disciplines,microfluidics has played an important role in research fields related to particle manipulation because of its easy integration and miniaturization.However,the development of microfluidic technology is limited to some extent by the single structure of microfluidic channels,the small size of particles and the difficulty of sequencing.In order to change this status quo,this paper uses the finite element analysis software COMSOL,designed acoustic single-point focusing,multi-point focusing model,based on acoustic metamaterials to improve the finite element analysis results of the acoustic field,to achieve a stronger acoustic field localization and focusing effect under low-power acoustic excitation,and then can explore the development of a more cost-effective acoustic microfluidic chip.The main research of the thesis includes:(1)Based on the two-dimensional three-component unit of phonon crystals,a toroidal columnar bilayer metamaterial structure has been designed to provide new ideas in manipulating the directional movement of particles,etc.The experimental results show that the acoustic waves emitted by the sound line source are confined inside the model after passing through the designed metamaterial model,resulting in an efficient focusing phenomenon at the geometric center of the model.The effect of the number of peripheral layers on the focusing effect of the geometric center was also explored.Two-and three-layer structures can significantly increase the sound pressure value at the focus point and multipole focusing phenomenon occurs at specific frequencies,which lays the foundation for the work in Chapter 4.(2)In order to achieve uniform distribution of acoustic energy over a wider area and efficient screening of particles,the multi-point focusing effect is achieved from two aspects respectively.Firstly,a strip structure model was designed,and the sound waves were excited from all around,and the sound amplitude inside the model was obviously enhanced,and the number of focal points increased with frequency,and the sound pressure value inside the model tended to zero when the frequency was too high.A similar effect can be produced when the line sources are placed in parallel;secondly,when the line sources are incident horizontally on the square array model structure,the sound pressure is regularly distributed alternately positive and negative,thus achieving the purpose of particle screening.When the sound source is in the diagonal of the square array,the line source can be converted into a sound point source at a specific frequency,avoiding the problem of acoustic waves interfering with each other and affecting the accuracy of the study.Therefore,the model size and acoustic incident frequency can be changed according to the actual needs to achieve the most ideal experimental results.This study aims to design and optimize the composite structure of acoustic metamaterials to achieve single-point focusing and multi-point focusing by using their highly efficient acoustic focusing characteristics in order to break through the current microfluidic technology bottleneck,which provides a theoretical basis for particle directed movement and cell sorting of a certain scale,and is of great practical significance for research in related fields.