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Magnetic plucking of piezoelectric bimorphs for a wearable energy harvester

Lookup NU author(s): Dr Michele Pozzi

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Abstract

A compact and low-profile energy harvester designed to be worn on the outside of the knee-joint is presented. Frequency up-conversion has been widely adopted in recent times to exploit the high frequency response of piezoelectric transducers within environments where only low frequencies are present. Contactless magnetic plucking is here introduced, in a variable reluctance framework, with the aim of improving the mechanical energy transfer into the transducers, which is sub-optimal with contact plucking. FEA and experiments were used to design an optimal arrangement of ferromagnetic teeth to interact with the magnets fixed to the piezoelectric beams. A prototype was made and extensively tested in a knee-joint simulator controlled with gait data available in the literature. Energy and power produced were measured for walking and running steps. A power management unit was developed using off-the-shelf components, permitting the generation of a stable and regulated supply of 26 mW at 3.3 V during walking. Record levels of rectified (unregulated) electrical power of over 50 and 70 mW per walking and running steps, respectively, were measured.

Publication metadata

Author(s): Pozzi M

Publication type: Article

Publication status: Published

Journal: Smart Materials and Structures

Year: 2016

Volume: 25

Issue: 4

Online publication date: 14/03/2016

Acceptance date: 09/02/2016

Date deposited: 04/03/2016

ISSN (print): 0964-1726

ISSN (electronic): 1361-665X

Publisher: Institute of Physics Publishing Ltd.

URL: http://dx.doi.org/10.1088/0964-1726/25/4/045008

DOI: 10.1088/0964-1726/25/4/045008

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