Transducer arrays from piezoelectric hollow spheres

Abstract

Directional transducer arrays were prepared from lead zirconate titanate based piezoelectric ceramic hollow spheres (BBs). Compared to a single sphere, a 4/spl times/4 array of 16 spheres connected in parallel has a 22 dB higher transmitting voltage response (TVR) and a few dB higher free field voltage sensitivity (FFVS), but when the spheres are connected in a mix of series and parallel the sensitivity is 10-12 dB higher. In an array of spheres connected in parallel, increasing the sphere size from (radius=1.15 mm) to (r=1.35 mm), or increasing the radiating area results in an increase of up to 15 dB in TVR. Omnidirectional response up to 50 kHz, and directional response above that was obtained.