The role of piezocomposites in ultrasonic transducers

Combining a piezoelectric ceramic and a passive polymer to form a piezocomposite allows the transducer engineer to design new piezoelectrics that offer substantial advantages over the conventional piezoelectric ceramics and polymers. The rod composite geometry provides materials with enhanced electromechanical coupling and with acoustic impedance close to that of tissue; these factors yield transducers for medical ultrasonic imaging with high sensitivity and compact impulse response. The dice-and-fill technique produces piezocomposites that can be readily formed into complex shapes to facilitate focusing the ultrasonic beam. Proper design of the rod spacing yields materials that exhibit low crosstalk between array elements formed by patterning the electrode alone, without cutting between the elements. In this way, curved annular arrays have been made that provide high-quality clinical images of substantial diagnostic value to physicians. Included is an extensive bibliography of papers documenting the role of piezocomposites in ultrasonic imaging transducers