Design, Fabrication and Testing Highly Sensitive Single Element Doppler Transducers

Abstract

Three common piezoelectric materials have been studied for use in pulsed wave Doppler ultrasound, where high sensitivity is required, while bandwidth is less important. A large transducer aperture, 80 mm 2 , results in a low electrical impedance, making the transducers challenging to drive with conventional electronics and cables. Air-backed transducers with electrical tuning circuitry and cable assembly were made using the piezoelectric materials Pz24, Pz27, and Pz29. Pz24 is a hard PZT, with dielectric constant of 240, the other materials are soft PZT with dielectric constants around 1000. It was found that the transducer made with Pz24 gave 2 dB better two-way sensitivity compared to those made with the other PZT-variants. The improved performance is explained by the higher electrical impedance from using pz24