Performance of Piezoelectric Power Generator in Environmental Conditions Seon-Bae Kim, Jung-Hyun Park, Hosang Ahn, and Dong-Joo Kim Materials Research and Education Center, Auburn University, Auburn, AL, 36849, USA E-mail: szk0022@auburn.edu ABSTRACT Piezoelectric power generators can be effective power suppliers for small devices by collecting energy from ambient vibration and converting it into electrical energy. Since such small devices are usually mobile, their operation environments can vary widely. For example, the conditions such as vibration frequency and temperature energy highly affect harvesting efficiency of piezoelectric power generators. If the ambient vibration frequency is away from the resonance frequency, there will be a decrease of output power. The ambient temperature can be a possible factor to change the resonance frequency of the power generating device since temperature influences material constants of the constituent components in a power generator such as dielectric constant, piezoelectric strain coefficient, and the stiffness Therefore, the effect of temperature on output power is studied. Since the common piezoelectric material is PZT and it is known that hard- or soft-type PZT exhibits different dependence of materials properties as a function of ambient temperature, this paper investigates the output power of the soft and hard PZTbased power generator depending on ambient temperature. INTRODUCTION Piezoelectric devices are widely studied as a potential power source for small devices. Most research on the characterization of piezoelectric power generators are performed at room temperature, but there are many applications where they have to operate at temperatures above the ambient. Therefore, it is important to know the behavior of their main parameters at different temperatures in order to make the proper design for any specific application. Piezoelectric devices should be maintained as a stable power source to ensure reliable operation. Although power change can be compensated by a circuit or program when environment temperature varies, it is required to investigate how its output power changes with the temperature and which parameters are mostly influenced by the temperature. For piezoelectric power generators, the most popular material is lead zirconate titanate (PZT) because of its high performance originated from a high dielectric constant and piezoelectric strain coefficient. PZT can be divided into soft and hard PZT depending on the valence state of dopants. Hard PZT is made by doping of lower valance state ions and soft PZT by higher valent dopants[1]. The dielectric constant and Proceedings of the SEM Annual Conference June 7-10, 2010 Indianapolis, Indiana USA ©2010 Society for Experimental Mechanics Inc. 25 T. Proulx (ed.), MEMS and Nanotechnology, Volume 2, Conference Proceedings of the Society for Experimental Mechanics Series 2, DOI 10.1007/978-1-4419-8825-6_4, © The Society for Experimental Mechanics, Inc. 2011
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