| Ultrasonic imaging has become one of the most valuable diagnostic tools in medical imaging due to its characteristics of simplicity,portability,low cost,safety,no radiation and real-time imaging.Compared with 2-D ultrasound imaging,3-D ultrasound imaging can more intuitively reflect the distribution of human tissue,so as to obtain more information,Since the1970 s,it has been widely concerned by many scholars.There are mainly three kinds of 3-D ultrasonic imaging: handheld,mechanical scanning and 2-D array electronic scanning,the imaging speed of handheld and mechanical ultrasonic transducer is slow,which cannot meet the real-time imaging requirements,however,2-D array ultrasonic transducer adopts pulse delay control to deflect and focus ultrasonic beam and obtain real-time 3-D ultrasonic image,which has become a research hotspot at present.This paper focuses on the 2-D array ultrasonic transducer for real-time 3-D imaging,Design the two different types of array ultrasonic transducer,One is used for intervention guided puncture of the high frequency miniature terraced array ultrasonic transducer,the other is a kiloarray full-channel array ultrasound transducer for real-time 3-D cardiac imaging.In the design and research of the high frequency miniature terraced array ultrasonic transducer,the transducer is designed and simulated,the transducer is prepared,and the electrical and acoustic properties of the transducer are tested and characterized.The results show that the capacitance of the high frequency miniature terraced array ultrasonic transducer is between 9-13 pf,the center frequency is 9.9 MHz,the relative bandwidth of-6 d B is 52.5%,the electric impedance at the resonant frequency of 10.8 MHz is 1.28 KΩ,and the electric impedance at the anti-resonant frequency of 11.5 MHz is 1.53 KΩ,the results of Wire Phantom Imaging by the transducer show that the axial resolution is in the range of 180-210 um and the lateral resolution varies with depth,in the range of about 280-1200 um.The comprehensive results show that the performance of the transducer is good,and it is expected to be developed into a safe and feasible endoscopic guided puncture interventional therapy technique in clinical practice.In the design and research of kiloarray full-channel array ultrasound transducer,a Sm-PMN-PT ceramic with ultra-high dielectric constant(>8000)was used to design and fabricate 2-D array transducers,the design is carried out in a 34×34 arrangement,the outermost array elements will be used as the ground array element,and the remaining 1024 array elements will be used as the array elements for transmitting and receiving ultrasonic waves,the pitch is 0.55 mm,the elements size is 0.45× 0.45 mm,and pitch is 0.1 mm,the electrical connection is realized through the coaxial line of the flexible circuit board and connector.The electrical and acoustic properties of the transducer were tested and characterized.The results show that the capacitance of the high frequency miniature terraced array ultrasonic transducer is between 75-125 pf,the center frequency is 3.1 MHz,and the relative bandwidth of-6 d B is 38.9%,the electrical impedance at the resonant frequency of2.48 MHz is 1855.7 Ω,and the electrical impedance at the anti-resonant frequency of 3.01 MHz is 4151.2 Ω,in the frequency range of 2-4 MHz,the crosstalk of the measured array is about-40 d B.The results of Wire Phantom Imaging by the transducer show that the lateral resolution of the array with aperture 1-4 is 2.7104 mm,2.7361 mm,2.7438 mm and 2.8875 mm,and the axial resolution is 1.1576 mm,0.7238 mm,1.0446 mm and 0.8675 mm,respectively.The results of Imitation tissue imaging experiments show that the contrast and noise ratios of aperture 1-4 are 20.66 d B,20.95 d B,19.10 d B and 21.63 d B,respectively.The comprehensive results show that the transducer has good performance and is expected to play a role in future clinical and therapeutic applications. |
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