A 7.5 MHz Linear Array Ultrasonic Probe Using Modified PbTiO 3 Ceramics

A high frequency (7.5MHz) linear array ultrasonic probe developed for medical use is presented. It employs modified PbTi03 ceramics having exceptionally large electromechanical anisotropy (ratio of electromechanical coupling factor for thickness vibration to that for planar vibration is more than 15). The advantage of employing such ceramics instead of usual PZT ceramics is that the width-to-thickness ratio of a transducer element can be chosen as w/t>l because of the very small planar or lateral electromechanical coupling factor. This advantage facilitates fabrication of high frequency linear array ultrasonic probes. These probes also employ two acoustic matching layers and a silicone compound lens with a low attenuation coefficient. The 7.5MHz linear array probe produces acoustic beams whose -6dB-width is less than 1.5mm. Some examples of 7.5MHz imaging present much better resolution than 5MHz imaging using PZT probes.