Development of an Multi-frequency Photoacoustic Endoscopy Probe Diagnosis System for Biomedical Applications

In endoscopic ultrasound (EUS) imaging, high-resolution and deep imaging depth are often desired. However, achieving high-resolution images requires the use of a higher frequency transducer, which in turn results in reduced imaging depth. This trade-off between high-resolution and imaging depth cannot be easily resolved. To address this issue, a cylindrical probe consisting of three 30 MHz transducers with different imaging depths was developed. This probe enables imaging with both high resolution and deeper depth, and the imaging results from the three transducers combined were found to be superior to those of a single transducer. The depth of field (DOF) of the fused images was also three times that of a single transducer. This technology will provide a clearer, more convenient, and efficient diagnosis of gastrointestinal diseases in the future. In this experiment, a triple-frequency cylindrical probe is designed, in which the frequencies of the three transducer elements are all 30 MHz, and the different detection depths of 10 MHz, 20 MHz and 30 MHz are simulated by the embedded depth. The sound field module uses PWM-PT as the piezoelectric material simulation, and a single frequency transducer is used to generate the sound field to display the imaging status and energy concentration at different imaging depths of 10 MHz, 20 MHz, and 30 MHz to detect whether the size of the piezoelectric material setup is consistent. In addition, in order to test the performance of the transducer and evaluate the imaging situation, the imaging situation of 10 MHz, 20 MHz and 30 MHz was observed at imaging depth of 1 mm for the designed transducer, and the results showed that 30 MHz had the best imaging effect. In addition, the photoacoustic and ultrasound images obtained by scanning pig intestines were fused using MATLAB. The fusion results show the multi-layered tissue echo signals and the distribution of hemoglobin in the tissue.