[Pb(Mg1/3Nb2/3)O3]0.63[PbTiO3]0.37 (PMN-PT) free standing film of comparable piezoelectric property to bulk PMN-PT with a thickness of 33 μm has been fabricated using a modified precursor coating approach. At 1 KHz, the dielectric constant and loss were 4,160 and 0.0291, respectively. The remnant polarization and coercive field were 28 μC/cm2 and 18.43 kV/cm. The electromechanical coupling coefficient kt was measured to be 0.55, which was close to that of bulk PMN-PT single crystal material. A high frequency (80 MHz) miniature ultrasonic transducer with high sensitivity was fabricated from this film. In vitro imaging of a rabbit aorta was performed to demonstrate the application of this material to intravascular ultrasound imaging at 80 MHz. Compared to a 35 MHz ultrasonic image, the 80 MHz image showed superior resolution and contrast.
We have investigated the development of a handheld 4 × 1 piezoelectric finger (PEF) array breast tumor detector system towards in vivo patient testing, particularly, on how the duration of the DC applied voltage, the depression depth of the handheld unit, and breast density affect the PEF detection sensitivity on 40 patients. The tests were blinded and carried out in four phases: with DC voltage durations 5, 3, 2, to 0.8 s corresponding to scanning a quadrant, a half, a whole breast, and both breasts within 30 min, respectively. The results showed that PEF detection sensitivity was unaffected by shortening the applied voltage duration from 5 to 0.8 s nor was it affected by increasing the depression depth from 2 to 6 mm. Over the 40 patients, PEF detected 46 of the 48 lesions (46/48)-with the smallest lesion detected being 5 mm in size. Of 28 patients (some have more than one lesion) with mammography records, PEF detected 31/33 of all lesions (94%) and 14/15 of malignant lesions (93%), while mammography detected 30/33 of all lesions (91%) and 12/15 of malignant lesions (80%), indicating that PEF could detect malignant lesions not detectable by mammography without significantly increasing false positives. PEF's detection sensitivity is also shown to be independent of breast density, suggesting that PEF could be a potential tool for detecting breast cancer in young women and women with dense breasts. Published by AIP Publishing. [http://dx
Pb(Mg 1/3 Nb 2/3 )O 3 ]0.63[PbTiO 3 ]0.37 (PMN-PT) freestanding film of comparable piezoelectric properties to bulk material with thickness of 30 µm has been fabricated using a modified precursor coating approach. At 1 kHz, the dielectric permittivity and loss were 4,364 and 0.033, respectively. The remnant polarization and coercive field were 28 μC/cm 2 and 18.43 kV/cm. The electromechanical coupling coefficient k t was measured to be 0.55, which was close to that of bulk PMN-PT single crystal material. Based on this film, high frequency (82 MHz) miniature ultrasonic transducers were fabricated with 65% bandwidth and 23 dB insertion loss. Axial and lateral resolutions were determined to be as high as 35 μm and 176 μm. In vitro intravascular imaging on healthy rabbit aorta and human coronary artery was performed from the thin film transducers. In comparison with a 35 MHz IVUS transducer, the 80 MHz one showed superior resolution and contrast with satisfactory penetration depth. The imaging results suggest that PMN-PT free-standing thin film technology is a feasible and efficient way in fabricating very high frequency ultrasonic transducers.
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