The pizzicato knee-joint energy harvester:Characterization with biomechanical data and the effect of backpack load

Pozzi, Michele, Aung, Min S.H., Zhu, Meiling, Jones, Richard K. and Goulermas, John Y. (2012) The pizzicato knee-joint energy harvester:Characterization with biomechanical data and the effect of backpack load. Smart Materials and Structures, 21 (7). ISSN 0964-1726

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The reduced power requirements of miniaturized electronics offer the opportunity to create devices which rely on energy harvesters for their power supply. In the case of wearable devices, human-based piezoelectric energy harvesting is particularly difficult due to the mismatch between the low frequency of human activities and the high-frequency requirements of piezoelectric transducers. We propose a piezoelectric energy harvester, to be worn on the knee-joint, that relies on the plucking technique to achieve frequency up-conversion. During a plucking action, a piezoelectric bimorph is deflected by a plectrum; when released due to loss of contact, the bimorph is free to vibrate at its resonant frequency, generating electrical energy with the highest efficiency. A prototype, featuring four PZT-5H bimorphs, was built and is here studied in a knee simulator which reproduces the gait of a human subject. Biomechanical data were collected with a marker-based motion capture system while the subject was carrying a selection of backpack loads. The paper focuses on the energy generation of the harvester and how this is affected by the backpack load. By altering the gait, the backpack load has a measurable effect on performance: at the highest load of 24kg, a minor reduction in energy generation (7%) was observed and the output power is reduced by 10%. Both are so moderate to be practically unimportant. The average power output of the prototype is 2.06±0.3mW, which can increase significantly with further optimization.

Item Type: Article
Uncontrolled Keywords: signal processing,civil and structural engineering,atomic and molecular physics, and optics,materials science(all),condensed matter physics,mechanics of materials,electrical and electronic engineering ,/dk/atira/pure/subjectarea/asjc/1700/1711
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Depositing User: LivePure Connector
Date Deposited: 26 Sep 2019 07:30
Last Modified: 22 Oct 2022 05:16
DOI: 10.1088/0964-1726/21/7/075023

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