Piezoelectric Ultrasonic Transducers

Abstract

This chapter addresses piezoelectric ultrasonic transducers that are specially designed to generate and receive sound waves in fluid media, i.e., air or water. Moreover, we will also discuss ultrasonic transducers for medical diagnostics. Section 7.1 deals with a semi-analytical approach to calculate sound fields and electrical transducer outputs for common transducer shapes, e.g., piston-type transducers. In doing so, the complex structure of a piezoelectric ultrasonic transducer is reduced to an active surface, which can generate and receive sound pressure waves. The semianalytical approach will be used in Sect. 7.2 to determine sound fields as well as directional characteristics of common transducers. Section 7.3 details the axial and lateral spatial resolution of spherically focused transducers operating in pulse-echo mode. In Sect. 7.4, we will study the general structure of piezoelectric ultrasonic transducers. This includes single-element transducers, transducer arrays as well as piezoelectric composite transducers. Afterward, a simple one-dimensional modeling approach is shown that allows analytical description of basic physical relationships for piezoelectric transducers under consideration of their internal structure. Section 7.6 contains selected examples for piezoelectric ultrasonic transducers. Finally, a brief introduction to the fundamental imaging modes of ultrasonic imaging will be given which is an important application of piezoelectric ultrasonic transducers.