Papers by Keyword: Piezoelectic

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Authors: Olga Korostynska, Abbasi A. Gandhi, Alex Mason, Ahmed Al-Shamma'a, Syed A.M. Tofail
Abstract: Hydroxyapatite (HA) is a leading biocompatible material extensively used for bone implants as a porous ceramic graft and as a bioactive coating. Electrical characteristics of HA can be employed in implantable devices for real-time in vivo pressure sensor applications such as in knee or hip prosthesis. In particular, high piezo and pyroelectricity of HA, its polarisation by electron beam and selective adsorption of proteins on polarised domains indicate the potential for real-time biosensing applications of HA. For this purpose, a comprehensive understanding of the dielectric behaviour of different forms of HA over a frequency range relevant for biomedical sensing is critical. Such information for HA, especially its frequency dependent dielectric behaviour over the GHz range, is rare. To this end, we report on novel investigations of properties of HA in powder and film forms in the GHz frequency range.
Authors: Sandy Zaehringer, Julia Purr, Norbert Schwesinger
Abstract: This paper will introduce a piezoelectric micro membrane actuator with interdigitated (IDT) surface electrodes for polarization and actuation. The thus achieved polarization and generated electric field are highly inhomogeneous and cause therefore also inhomogeneous strain and stress distributions within the piezoelectric material itself. To equalize the strain and stress the material will deform. This deformation can be manipulated due to electrodes design and clamping of the membrane. The most outstanding achievement with this manipulation is the deflection of the membrane towards the actuated surface and not as is common in piezoelectric membrane actuators towards the passive surface of the device.
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