Design and development of a broadband spherical hydrophone using PZT-4

Majority of the sensors for underwater application use acoustic waves for detection, communication and navigation of submersibles. Hydrophone, used for sensing acoustic signals in water, has piezoelectric material within which responds to acoustic pressure by generating electric potential. Different types of hydrophones having different shapes can be manufactured depending on their applications. An omni-directional hydrophone can be developed using a spherical piezoelectric material as active material. This paper describes the design and development of a spherical hydrophone using lead zirconate titanate-4 (PZT-4) hollow sphere, having Receiving Sensitivity (RS) − 205 ± 0.6 dB ref 1 V/µPa in the frequency band 0–10 kHz. Analytical modelling of the piezoelectric sphere is done to fix its dimensions for the desired output and numerical analysis is done in COMSOL Multiphysics to validate the result. Since the spherical hydrophone is manufactured by encapsulating the piezoelectric sphere with polymer to give water-tight insulation, numerical analysis of the piezoelectric sphere coated with a polymer is done to calculate the RS of the hydrophone. Fabrication of a spherical hydrophone is done by rubber encapsulation of the piezoelectric sphere using compression moulding technique and its RS is measured in water. RS values obtained from numerical analysis and experiment are having a good agreement in the frequency band 0–10 kHz.