Theoretical and Experimental Studies on Sensitivity and Bandwidth of Thickness-Mode Driving Hydrophone Utilizing A 2-2 Piezoelectric Single Crystal Composite

• Published in: Sensors (Basel, Switzerland) Switzerland), 2023-03, Vol.23 (7), p.3445
• Main Authors: Je, Yub, Sim, Minseop, Cho, Yohan, Lee, Sang-Goo, Seo, Hee-Seon
• Format: Article
• Language: English
• Subjects: 2-2 piezoelectric composite; Acoustic impedance; Acoustics; Bandwidths; Bridgman method; broadband hydrophone; Comparative analysis; Composite materials; Composite structures; Configurations; Connectivity; Epoxy resins; Hydrophones; Material properties; Numerical analysis; Open circuit voltage; PIN-PMN-PT; Polymers; Sensors; Single crystals; Thickness; thickness-mode hydrophone; Transducers; Underwater acoustics
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s23073445

Piezoelectric composites, which consist of a piezoelectric material and a polymer, have been extensively studied for the applications of underwater sonar sensors and medical diagnostic ultrasonic transducers. Acoustic sensors utilizing piezoelectric composites can have a high sensitivity and wide bandwidth because of their high piezoelectric coefficient and low acoustic impedance compared to single-phase piezoelectric materials. In this study, a thickness-mode driving hydrophone utilizing a 2-2 piezoelectric single crystal composite was examined. From the theoretical and numerical analysis, material properties that determine the bandwidth and sensitivity of the thickness-mode piezoelectric plate were derived, and the voltage sensitivity of piezoelectric plates with various configurations was compared. It was shown that the 2-2 composite with [011] poled single crystals and epoxy polymers can provide high sensitivity and wide bandwidth when used for hydrophones with a thickness resonance mode. The hydrophone element was designed and fabricated to have a thickness mode at a frequency around 220 kHz by attaching a composite plate of quarter-wavelength thickness to a hard baffle. The fabricated hydrophone demonstrated an open circuit voltage sensitivity of more than -180 dB re 1 V/μPa at the resonance frequency and a -3 dB bandwidth of more than 55 kHz. The theoretical and experimental studies show that the 2-2 single crystal composite can have a high sensitivity and wide bandwidth compared to other configurations of piezoelectric elements when they are used for thickness-mode hydrophones.