Micromachined self-focusing piezoelectric composite ultrasonic transducer

Usually focused transducers have acoustical lens or large concave surface in order to generate focused high intensity ultrasound beam. Therefore these traditional focusing transducers are commonly large in size and long in focal length, which are not suitable for interventional ultrasound imaging or therapy. For solving this problem, in this paper, a micromachined self-focusing piezoelectric composite ultrasonic transducer was designed and evaluated. The theoretical analysis was deduced based on the electromechanical response of piezoelectric composites and theory of Fresnel half-wave band interference. This self-focusing transducer has many advantages, including micro size, short focal length, low acoustic impedance, high electromechanical coupling coefficient. Besides these, because it was based on micro-electromechanical systems, the fabrication process precision is high and reliable. These results hold good potential for interventional ultrasound therapy or imaging applications.