Single element high frequency (<50 MHz) PZT sol gel composite ultrasound transducers

A sol gel composite process has been used to produce lead zirconate titanate coatings in the thickness range of 3 to 100 /spl mu/m on aluminum substrates. The complex permittivity (/spl epsi//sub 33//sup S/), elastic stiffness (c/sub 33//sup D/), and the piezoelectric constant (h/sub 33/) of the coating and the complex elastic stiffness (c/sub 33//sup D/) of the substrate have been determined using impedance measurements and a commercially available software program [Piezoelectric Resonance Analysis Program PRAP 2.0, TASI Technical Software, Kingston, Ontario, Canada]. The complex components of the material parameters account for the losses within the film and the substrate. Sol gel composite films on aluminum have a dielectric constant of 220 with an imaginary component of 1% and an electromechanical coupling coefficient of up to 0.24 with an imaginary component of 3%. These films are applied to the fabrication of a high frequency transducers suitable for ultrasound biomicroscopy (UBM). By combining the sol gel composite material with existing transducer fabrication techniques, single-element focusing transducers have been produced that operate in the frequency range of 70 to 160 MHz. Devices have -6-dB bandwidths up to 52% and minimum insertion losses ranging from -47 to -58 dB. Real-time images of phantom materials and ex vivo biological samples are shown.