Therapeutic array transducer element using coresonance between hemispherical piezoceramic shell and water sphere: Effect of load masses of support and electric contact

For therapeutic ultrasound array transducers, it is necessary to reduce the electrical impedance of their elements so that the transducer can produce high ultrasonic power at a relatively low drive voltage. For this purpose, a new concept of a breathing-mode piezoceramic transducer element has been proposed. Numerical simulation showed its low electric impedance as well as good acoustical coupling between the concave hemispherical piezoceramic shell, with a diameter on the order of a wavelength in water, and the volume of a water sphere half enclosed by the shell. In the preparation of a prototype transducer, the effect of additional load masses of the flange supporting the shell and the electric contact for driving the element was numerically analyzed in this paper.