Acoustofluidic Fields In Cylindrical Channels And Their Applications In Micro/Nanoparticle Manipulation

Precise manipulation of micro and nano particles is a key step in realizing many applications in biomedicine and other fields(e.g.,detection and identification of bacteria,circulating tumor cells,assessment of water and food quality,etc.).In recent years,ultrasonic microfluidics has attracted a lot of attention as a non-contact manipulation technique for the manipulation of micro and nano particles within microchannels.At present,the mainstream ultrasonic micro-nano particle manipulation devices are dominated by rectangular cross-section channels and their acoustic fluid morphology has been widely and deeply studied,but the relevant theory in cylindrical flow channels still needs to be improved.In this paper,some mature research methods and theories in rectangular cross-section microchannels are extended to the study of acoustic fluid morphology in cylindrical flow channels.The study of the acoustic fluid morphology inside the cylindrical flow channel provides a theoretical basis for the design of micro and nano particle manipulation devices and related technology applications.The main work of the paper is as follows.(1)First,the limiting velocity method,which is commonly used for rectangular cross-section microchannels,is extended to apply to cylindrical curved microchannels.On this theoretical basis,a two-dimensional numerical model simulating the boundary-driven acoustic flow field is established using COMSOL software,and the results of the acoustic field distribution,acoustic radiation force distribution,acoustic flow field morphology and particle motion trajectory in the main(1,0)mode are derived,and the influence of these results on the acoustic swimming of particles in a circular cross-section microchannel is analyzed,which has important implications for the design of particle manipulation devices.(2)Then,an experimental device for rapid two-dimensional aggregation of particles is designed with the guidance of numerical model,an efficient observation method for rapid determination of three-dimensional acoustic dynamics behavior of particles in microchannels is proposed,and a fixture for adjusting the rotation angle of microfluidic channels is designed for this observation method.On this basis,experiments are conducted on one-dimensional acoustic field and two-dimensional orthogonal acoustic field respectively to verify the correctness of the theoretical and simulation studies,explain the mechanism of rapid particle aggregation,and realize the application of cylindrical flow channels for micro-scale particle manipulation.(3)Finally,the higher-order modes of the cylindrical microchannel are explored,and an acoustic manipulation device to realize the three-dimensional arrangement of particles is designed to realize the arrangement of unconventional Chaldni patterns using the vibration of the cylindrical cavity wall;combined with the experimental device,the observation method is improved to realize the visualization of particles in the cross-section of the microchannel and in the direction of the flow channel,which provides a feasible solution for the pattern arrangement and three-dimensional observation of particles.