Function-design And Particle-manipulation Of Sound Field Based On Artificial Structures And Multiarray Transducers

In recent years,the interaction between artificial modulated sound field and matter has gradually become a focal point in the academic field.It can be used to achieve the non-destructive control of biological macro molecules and various particles,and has a wide application prospect in medical,pharmaceutical and industrial fields.For example,using artificial acoustic structure or multi-element transducer to control the phase of sound field to realize the acoustic vortex field,using artificial modulation of standing wave sound field to achieve cell suspension and screening,and using the phase control of artificial acoustic structure to achieve ultrasonic focusing and imaging etc.Compared with using a single transducer to regulate the sound field,the acoustic artificial structure and multi-element transducer have better flexibility in regulating the sound field.Therefore,researchers choose to use the acoustic artificial structure or multi-element transducer to obtain special sound field and complex sound field which are difficult to be realized by a single element transducer,so as to meet the actual needs of many researches.In this paper,we first design and prepare artificial acoustic structure and multi-element transducer to realize the vortex sound field,and then analyze the sound radiation force effect of particles in the sound field,which provides a new technical scheme and idea for the realization of ultrasonic cleaning using vortex sound field.Finally,we designed a ballshaped lens to realize the focusing sound field,and studied the acoustic characteristics of the focusing sound field and the suspension phenomenon of particles.Details of our research are included in the following parts:In the second chapter,an artificial acoustic structure with gradient spiral shape on one side is designed and manufactured.Through the artificial acoustic structure,the plane acoustic wave can be transformed into acoustic vortex field.Our theoretical and experimental results showed that the acoustic vortex field can be used in the study of ultrasonic cleaning.We initially analyzed the physical mechanism of ultrasonic cleaning in the acoustic vortex field,and it showed that the polluted glass surface can be cleaned by the acoustic vortex field.Moreover,it can also avoid the corrosion caused by cavitation effect,which proved that the technology can be different from the traditional ultrasonic cleaning method.Thus,this technology can be better applied to the ultrasonic cleaning of precision instruments.In the third chapter,an eight element transducer is theoretical simulation and fabricated.The first-order acoustic vortex field with spiral wavefront distribution is obtained by changing the output phase of the acoustic wave under the condition that different elements can transmit delay signals separately.In addition,the eight element transducer can adjust the acoustic vortex field from low order to high order by changing the signal transmitting time.Finally,it is proved that the acoustic vortex field constructed by the eight element transducer can be applied to ultrasonic cleaning.It can clean the dirt and simultaneously avoid the disadvantage of ultrasonic cleaning which will shorten the service life of the workpiece.This provides a new idea and technology for the ultrasonic cleaning industry.In the fourth chapter,we also studied the particles in the focused sound field will move to the sound well under the influence of the sound radiation force,achieving particle suspension.First of all,we designed and prepared a ball-shaped lens,and then analyzed the distribution of acoustic radiation force and sound pressure field of the focused sound field based on the ball-shaped lens.Finally,though theoretical simulation and experiment,we verified that a polystyrene particle suspending in the focused sound field,which provided a new method and means for the acoustic control of particle suspension technology.