Medical ultrasonic transducers with switchable frequency bands centered about f/sub 0/ and 2f/sub 0/

Abstract

We present a novel type of ultrasonic imaging transducer in which the operating frequency can be switched between two distinct bands centered about f/sub 0/ and 2f/sub 0/. In effect, we can achieve greater than 100% transducer bandwidth at the -6 dB level. The transducer is based on using DC bias induced piezoelectricity in electrostrictive materials such as lead magnesium niobate-lead titanate (PMN-PT) relaxor ferroelectric materials.