Research On Acoustic Tweezers Based On Equilateral Triangular Cross-section Resonator

As a non-contact micro-nano particle manipulation technology acoustic tweezers play an important role in the fields of physics,chemistry,and biomedicine.At present,the research on acoustic tweezers system mainly focuses on the acoustic fluid effect in rectangular and circular cross-section channels and the acoustic dynamic behavior of particles.However,there is still a lack of systematic research on the acoustic fluid morphology in the channel with triangular and other special-shaped cross-sections and its application in the manipulation of micro-nanoscale particles.In this thesis,the main research object is the regular triangular cross-section channel.By establishing a reduced flow field numerical model and an ultrasonic microfluidic experimental device,from the perspective of simulation and experimentation,the acoustofluid morphology and the acoustics of micro-nano particles in the triangular cross-section channel with different structures are explored from the perspective of simulation and experiment.The dynamic behaviors lay a theoretical and experimental basis for the application of more complex special-shaped cross-section channels in ultrasonic micro-nano manipulation.The main work of the thesis is as follows:（1）A reduced numerical model of the flow field is established to elucidate the acoustic dynamics mechanism of micro-nano particles of different scales in the equilateral triangular resonator.Based on the Helmholtz equation,the sound field modes of the equilateral triangular cross-section resonator at each eigenfrequency are solved by COMSOL5.5 simulation software,and the acoustic radiation force distribution and its dominant micrometer scale under each sound field mode are solved by the Gorkov equation.movement of particles.A limiting velocity method is established for solving the shape of the acoustic streaming in the triangular cross-section resonator,and the shape of the external acoustic streaming under different sound fields is simulated,and then the motion law of the nano-scale particles is obtained.（2）An ultrasonic microfluidic device based on an equilateral triangular resonator was built,an efficient optical observation method was designed,and the quantitative characterization of the acoustic dynamic behavior of particles of different sizes on the channel section under different sound fields was realized,and the numerical theoretical model was verified.In particular,it was found experimentally for the first time that there is a spatial separation between the acoustic streaming separation point and the sound pressure node in the asymmetric standing wave field,which verifies the relevant theoretical models in the recent literature.（3）Guided by the numerical model of the equilateral triangular cross-section resonator,a general isosceles triangle numerical model is established,and the acoustic field modes in the isosceles triangle resonator with different angles,the external acoustic streaming shape and the acoustic dynamics of micro-nano particles of different sizes are solved.It provides guidance for the application of isosceles triangular resonators with different angles in ultrasonic micro-nano manipulation.