Power Generation from Piezoelectric Lead Zirconate Titanate Fiber Composites
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Power Generation from Piezoelectric Lead Zirconate Titanate Fiber Composites Farhad Mohammadi, Ajmal Khan, and Richard B. Cass Advanced Cerametrics, Inc. 245 N. Main Street Lambertville, NJ 08530, U.S.A. ABSTRACT Power generation from lead zirconate titanate (PZT) piezoelectric fibers in the form of 1-3 composites under application of an external force was investigated. Green fibers consisting of PZT powder dispersed in a cellulose binder were made by the Viscous Suspension Spinning Process (VSSP). The composites were made by firing sheets of parallel green PZT fibers at 1270 °C, and then laminating the sintered sheets in epoxy. Composites of several PZT fiber diameters (15, 45, 120, and 250 µm), with the fiber volume fraction fixed at ~0.4, were investigated. Transducers comprised of electrode and poled plates of the composites, in which the plate thickness direction was in the fiber axis direction, were made. Power generation experiments were conducted by dropping a 33 g stainless steel ball onto the electroded face of each transducer from a height of 10 cm and recording the output voltage on an oscilloscope. A peak voltage of 350 V corresponding to 120 mW of peak power was obtained. The output voltage and power was the highest for the transducers made with the smallest diameter fibers (15µm) and increased with increasing of transducer thickness. The average piezoelectric coefficient, d33, of the transducers was about 300 pC/N and decreased with decreasing transducer thickness. In this paper, the power generation capability and dielectric properties of the laminated 1-3 fiber composites are discussed. INTRODUCTION The ability of piezoelectric materials to generate electric power, from otherwise wasted mechanical energy, such as that associated with structural vibrations, has given rise to significant interest for numerous microelectronic and wireless systems that require low power [1, 2]. Wireless sensor systems that are self-powered can substantially reduce the cost of conditionbased maintenance in numerous civilian and military applications. Piezoelectric transducers can be used to generate electric energy to be used in low power devices far beyond the life span of currently used batteries. Such self-powered systems would eliminate the use of batteries and wires, and therefore, reduce the cost and labor in health monitoring applications. Piezoelectric materials have been widely used in sensors and actuators [3]. These materials develop an electric charge proportional to a mechanical stress (direct effect), and a geometrical strain (deformation) proportional to an applied voltage (converse effect) [4]. The converse effect is used in piezoelectric actuators, ultrasonic cleaners, etc. however, it is the direct effect that is used to generate electric charge. The charge generated is proportional to the applied pressure. This proportionality can be expressed in matrix notation in terms of dielectric displacement D (charge, Q, per unit area; Coulomb/meter2-C/m2), which is a measure of charge storage or polariz
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