[Show abstract][Hide abstract] ABSTRACT: A miniature fiber-tip pressure sensor was built by using an extremely thin graphene film as the diaphragm. The graphene also acts as a light reflector, which, in conjunction with the reflection at the fiber end-air interface, forms a low finesse Fabry-Perot interferometer. The graphene based sensor demonstrated pressure sensitivity over 39.4 nm/kPa with a diaphragm diameter of 25 mu m. The use of graphene as diaphragm material would allow highly sensitive and compact fiber-tip sensors. (C) 2012 Optical Society of America
[Show abstract][Hide abstract] ABSTRACT: High-frequency (25 MHz) ultrasonic transducers with Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>-BaTiO<sub>3</sub> (NBT-BT) lead-free piezoelectric single crystal as the active elements are fabricated and characterized. The impedance measurement reveals that the poled -oriented NBT-BT single crystal exhibits a high thickness electromechanical coefficient k<sub>t</sub> of 0.52 and a low clamped dielectric constant of 80. The -6-dB bandwidth of the transducer is 46.16% and the insertion loss at the center frequency is -31.89 dB. The good performance of the transducer indicates that the NBT-BT single crystal would be a promising lead-free material for ultrasonic transducer applications.
No preview · Article · Dec 2010 · IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control