Polymer-metal front matching layers for ultrasonic transducers with arbitary impedance conversion

This paper presents a novel design principle for ultrasonic transducers, introducing multilayer polymer-metal structures which are well suited for impedance matching between high impedance piezoelectric ceramics and water or human tissue. It is shown that an inner polymer layer with an outer metal layer, when loaded by a low acoustic impedance propagation medium, acts as an efficient impedance converter.