40-MHZ MICROMACHINED PMN-PT COMPOSITE ULTRASOUND ARRAY FOR MEDICAL IMAGING

Ultrasonography is well known as a relatively low cost and non-invasive modality for real-time imaging. In recent years, various high frequency array transducers have been developed and used for ophthalmology, dermatology, and small animal studies. This paper reports the development of a 48 element 40-MHz ultrasonic array using micromachined lead magnesium niobate-lead titanate (PMN-PT) single crystal 1-3 composite material. Array elements with a pitch of 100-micron were interconnected via a customized flexible circuit. Pulse-echo test showed an average center frequency of 40 MHz and a -6 dB fractional bandwidth of 52%. The -20 dB pulse length was evaluated as 120 ns. The electrical and acoustical separation showed the crosstalk less than-24 dB. An image of a steel wire target phantom was acquired by stacking multiple A-lines. The results demonstrate resolutions exceeding 70 gm axially and 800 gm laterally. Those results imply the great potential of the developed array transducer for the high frequency medical imaging.