Research Of A Shell-focused Transducer Based On 1-3 Piezoelectric Composites

High intensity focused ultrasound technology has been successfully applied to the treatment of clinical cancer and non tumor diseases, and has been hailed as the world’s leading edge in science and technology. The transducer is the key device of the focused ultrasound equipment, and its performance directly affects the therapeutic effect. At present, the transducer we are using is Pb-based lanthanum doped zirconate titanates piezoelectric ceramic shell type focusing transducer. But the transducer has some problems, such as high impedance, narrow bandwidth, low energy conversion rate, and so on. In this paper, I used a new type of 1-3 piezoelectric composite material as focused ultrasound transducer’s material to solve these problems. Meanwhile, I also designed and made a 1-3 piezoelectric composite shell focusing transducer with opening radius being 6cm, focal length being 12 cm.In this project, I have mainly done the work concluded four sides.Firstly, 1-3 piezoelectric composites were made by cutting and filling method, and the preparation of the composite electrode was solved, breaching the nickel plating technology of Electrode chemistry with regard to 1-3 piezoelectric composite and solving the problem of electrode adhesion, high cost of equipment and so on.Secondly, new material’s properties were tested and its results were compared and analyzed with PZT materials. We confirmed that 1-3 piezoelectric composite material has the characteristics of pure vibration mode, better piezoelectric performance, low impedance and wide frequency band, which can be used as a new type of material for the transducer.Thirdly, 1-3 piezoelectric composite spherical shell type focusing transducer was designed and made by me. By comparing the frequency characteristics of the transducer and the electro acoustic conversion efficiency with PZT piezoelectric ceramic shell type focusing transducer, we find that 1-3 type piezoelectric composite shell focusing transducer has a low impedance,a relative wide band up to 61%which is 3.39 times of the PZT piezoelectric ceramic shell type,and a higher electro acoustic conversion efficiency with η at 54% which is 1.68 times of the PZT piezoelectric ceramic shell type focusing transducer.Finally, sound fielding of the designed transducer was tested by using piezoelectric hydrophone in the direction of acoustic axis and the perpendicular direction of the acoustic axis or the surface of XOY in electric power 30 W. The results showed consistency between the detection result of sound field and the simulation result using Matlab sound field. In this paper, the 1-3 type piezoelectric composite shell type focusing transducer studied by us has better sound field characteristics and focusing effect. This project provides a theoretical and experimental basis for the realization of high performance focused transducers.