Research On Focusing Imaging Method Of Photoacoustic Signal Based On Acoustic Metamaterial

The early diagnosis and identification of breast cancer is an important topic related to the overall national health.Photoacoustic imaging technology has shown its advantages in this important topic by virtue of its excellent imaging ability and high biosafety.The development trend of photoacoustic microscopy requires the realization of sub-wavelength high-resolution imaging of tiny tissues,but the current technology is difficult to achieve sub-wavelength resolution.In this paper,we mainly draw on the technical advantages of acoustic metamaterials in near-field photoacoustic imaging,use artificial periodic structures to modulate transmission wavefronts,and design the near-field linear acoustic source focusing model,multifocal acoustic focusing model and acoustic lens structure.The main contents of the paper include:1.In view of the limitations of ultrasonic precise positioning of tiny tissues,the paper studies the transmission wavefront modulation using artificial periodic structure in combination with acoustic metamaterials,and realizes the focusing effect from line source to point source.When the initial value of sound pressure is set at 100 Pa,the peak value of sound pressure inside the model increases with the increase of frequency,reaching 1000 Pa at the highest,achieving accurate positioning of a single tiny tissue.When the point source sound pressure value is used as the secondary sound source to refocus,the energy value of the emitted sound wave reaches150 Pa,which is 1.5times higher than the original sound pressure value,realizing the accurate positioning of multiple tiny tissues.2.Based on acoustic metamaterials,a local resonance model was designed to achieve acoustic focusing effects,thus providing a basis for the use of models to arrange multiple microparticles in an orderly manner.Through the corresponding simulation experiments and analysis,it can be concluded that the designed model can indeed achieve the purpose of multifocal acoustic focusing.This regular arrangement does not occur in special cases,but in many cases.3.This section proposes a new basic structure of acoustic elements,which is modeled and simulated by COMSOL finite element simulation software.The results show that the model has longitudinal ultrasonic wave transmission effect and energy focusing effect,and the triangular array has more concentrated energy than the rectangular array.This method can eliminate the influence of ultrasonic longitudinal wave transmission on the energy loss of the energy field greatly,thus improving the practical application of ultrasonic longitudinal wave.