Engineering the electromechanical response of piezoelectric transducers: Some challenging applications

Abstract

Piezoelectric transducers are widely used for ultrasonic applications both as actuators to excite and as sensors to receive vibration/wave response. The electromechanical characteristics of the piezoelectric transducers dictate their choice for specific applications. These can be tuned in several ways ranging from modifying the geometry and material properties of the element to changing the excitation electrode pattern and the boundary conditions of the vibrating piezoelectric element. This talk discusses two different ways to achieve such tuning for single-element piezoelectric transducers and their corresponding applications. The first application is to achieve a low-frequency collimated beam using lateral stiffening of a piezoelectric disc vibrating in its radial resonance. The resonance and vibration characteristics of such a disc are presented and the ultrasonic wave propagation from such a laterally stiffened disc in fluids is discussed. The second application uses tailored polarization profiles for piezoelectric elements to enhance/suppress specific resonant modes in an otherwise homogeneous element. The fundamental theory for such behavior is presented and some applications of such polarization-tuned piezoelectric elements are discussed.