PMN-PT single crystal focusing transducer fabricated using a mechanical dimpling technique

A ∼5 MHz focusing PMN-PT single crystal ultrasound transducer has been fabricated utilizing a mechanical dimpling technique, where the dimpled crystal wafer was used as an active element of the focusing transducer. For the dimpled focusing transducer, the effective electromechanical coupling coefficient was enhanced significantly from 0.42 to 0.56. The dimpled transducer also yields a -6 dB bandwidth of 63.5% which is almost double the bandwidth of the plane transducer. An insertion loss of the dimpled transducer (-18.1 dB) is much lower than that of the plane transducer. Finite element simulation also reveals specific focused beam from concave crystal surface. These promising results show that the dimpling technique can be used to develop high-resolution focusing single crystal transducers.