Stefon E. Shelton

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Air-coupled piezoelectric micromachined ultrasonic transducers (PMUTs) operating at frequencies ranging from 0.3 MHz to 0.9 MHz were designed, fabricated and characterized. We increased the fractional bandwidth by 51% and improved the piezoelectric coupling over 80% by patterning the diaphragm center into a ring or structural ribs, resulting in a reduction(More)
This paper presents a 1.2 mm diameter high fill-factor array of 1,261 piezoelectric micromachined ultrasonic transducers (PMUTs) operating at 18.6 MHz for intravascular ultrasound (IVUS) imaging and other medical imaging applications. At 1061 transducers/mm, the PMUT array has a 10-20× higher density than the best PMUT arrays realized to date. The PMUTs(More)
A two-port piezoelectric micromachined ultrasound transducer (pMUT) has been demonstrated using aluminum nitride (AlN) as the piezoelectric material with good linearity, high acoustic pressure per unit input voltage, and enhanced electromechanical coupling factor. Experimental data are found to match well with values predicted by the theoretical models. The(More)
Air-coupled piezoelectric micromachined ultrasound transducer arrays, operating at ~190 kHz, have been fabricated utilizing an aluminum nitride piezoelectric layer. Improved fabrication processes have reduced the frequency variation seen in our previous work with single transducers resulting in arrays of transducers with resonant frequencies (fn) that match(More)
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