Optimization of acoustic matching layers for piezocomposite transducers

At present, lot of piezoelectric broad band ultrasonic transducers use as active material piezoelectric ceramic composites. In a typical transducer based on piezocomposites the active material is mounted on a soft backing and one matching layer is placed on the front, radiating face, with the aim to match the acoustic impedance of the medium and to enlarge the bandwidth. In this paper an optimization work is shown to demonstrate that a composite configuration can be used in the matching layer in order to improve the efficiency and the band of the transducers. An approximated two-dimensional analytical model has been used to optimize the design of a composite-structured matching layer in the case of 2-2 composites, obtaining different results for the polymer and piezoceramic composite phases.