Development of a multifrequency ultrasonic transducer using PZT/polymer 1–3 composite

Abstract

In a number of clinical examinations using ultrasound, it is advantageous to be able to examine a patient at different frequencies. Low frequency is used to obtain images with adequate penetration and high frequency is used to obtain images with fine resolution. In this paper the feasibility of constructing a multiple-frequency transducer using piezoelectric composite is examined. The transducer is comprised of piezoelectric ceramic rods embedded in a polymer matrix. By selecting the appropriate thickness and width of ceramic rod, the transducer assembly can be made to resonate at a number of frequencies as predicted by the mode coupling theory. One of the resonance frequencies is determined by the width of the ceramic rod; other resonance frequencies are determined by the width-to-thickness ratio of the ceramic rods. A number of multiple-frequency transducers were constructed and the results correlate well with the theoretical prediction.