Bonded multilayer crystal technology will be developed for ultrasound transducer applications. Single crystal materials have demonstrated enormously high coupling constants, over 94% in some modes. Bonded multilayers have already been demonstrated to maintain the coupling inherent in the base material, and to result in an effective increase in the dielectric constant of the structure equal to the square of the number of layers. The application of multilayers to single crystals will result in what should be considered the ultimate trasnducer material. Multilayer crystal composites will have a low acoustic impedance, and a very high effective dielectric constant and coupling coefficient. Modeling shows that the bandwidth that will be obtainable with these devices will exceed 120%, even for arrays which normally are severely limited because of the much lower dielectric associated with traditional materials and configurations. The benefits of applying these materials to ultrasonic arrays will be much higher bandwidth and sensitivity of devices, particularly those which are usually limited by element area, such as phased arrays and 1.5-D and 2-D arrays. Even single crystals are limited in their performance without the capacitance increase associated with a multtilayer.
