Miniature Ultrasonic Probe For Medical Ultrasonic Endoscope Design Studies

This paper focuses on making a serious of research to the medical ultrasonic endoscope system. It's mainly about the ultrasonic detector of ultrasonic endoscope.Now, the rapidly developing ultrasonic sensor technology, MEMS technology, computer technology and other high-end electronics technology are confluence with endoscopic ultrasonography system (EUS). These are making the ultrasonic endoscope technology rapidly developing. On the basis of the electronic endoscope system, medical ultrasonic endoscope system put the ultrasonic detector into the human body through electronic endoscopic biopsy channel. The differences of ultrasonic endoscope and electronic endoscope is that it not only diagnose the lesions of organs'mucosal surface by ultrasonic endoscope, but also can get the histologic features of organs'each faults by ultrasonic scanning. Due to the electromagnetic motors have many shortcomings, and these shortcomings prevent the ultrasonic endoscope from better playing advantages, so this paper usus the bending vibration modal ultrasonic motor, it delivers the energy through the friction produced by the bending vibration vibrator. Because the paper uses the acoustic mirror to achieve sector scanning, it avoid the short life bring by rotating transducer. So, ultrasonic motor connect with acoustic mirror by a shaft, and realize rotating.About the probe design, the key is the design of ultrasonic transducer. The performance of the transducer depends on the materials, structure form, imaging parameters and installation of the transducer. First of all, the paper analyzed the equivalent model of transducer, the sensitivity and transducer impedance matching problem contacted the piezoelectric materials and polymer materials for analysis. The material selection of transducer determined by comparing performances' advantages and disadvantages of lead zirconate titanate with polymer piezoelectric material. Although the various functions of circle array transducer can meet all requirements of ultrasonic endoscope system, the disadvantages are difficult to production, complex process, high cost, so, it against the popularization of medical ultrasonic endoscope. Finally, the determination make use of spherical transducer, compare with piston transducer, its sound radiation area becomes larger, the sound field density becomes larger, depth of field becomes larger. It compares with the focus of acoustic lens, to avoid the loss of sound energy, it can meet the requirements. Acoustic mirror achieve the sector scanning through rotating the acoustic mirror, the transducer is fixed, it avoid the trouble that rotate the transducer must use of the rotating equipment. So this design uses of the sound reflector installation. This paper makes some improvement through using of above of scheme, it makes a good foundation to some needs that no electromagnetic interference, long life, wide bandwidth, high sensitivity, low cost and so on.