Energy harvesting from human body motion has been investigated extensively in the last two decades due to the increasing demand for Smart Wearables. Smart Wearables are beneficial in terms of monitoring of vital parameters that can be used to indicate the human health condition. However, sensors and electronics of Smart Wearables are conventionally supplied by batteries that exhibit restrictions such as limited lifetime and replacing/charging processes. Since self-powering devices are highly promising for the exploitation of application areas of Smart Wearables, it is aimed to harvest electric energy from human body motions. In terms of self-powering Smart Wearables, specific challenges need to be faced such as low frequency range of body motions as well as wearing comfort.Among diverse principles for energy harvesting, the piezoelectric principle has been a preferred principle in terms of energy efficiency. Numerous studies address the use of piezoelectric ceramics such as PZT-5H or PZT-8 for energy harvesting, which have a high electrical power density due to their piezoelectric coefficient. However, the high mass density and the high modulus of elasticity limit the &nbsp;energy harvester designs based on piezoelectric ceramics to rather heavy wearables such as shoes or backpacks. In terms of lightweight designs, polymers such as PVDF (polyvinylidene fluoride) have been considered and investigated as functional materials in several researches but these materials are disadvantageous regarding energy efficiency. Consequently, piezoelectric electrets (piezoelectrets, also referred to as ferroelectrets) are auspicious functional materials for energy harvesting from body motions due to their high piezoelectric coefficient and low mass density. Piezoelectrets facilitate the implementation of lightweight energy harvester designs with high energy output that is beneficial for applications in context of wearable devices. In particular, fluorethylpolypropylene (FEP) piezoelectrets with parallel tunnel structures are promising regarding the use as generators for energy harvesting.Within the present work, a novel concept of energy harvester based on FEP piezoelectrets is introduced and validated by means of an experimental setup with respect to a wearable application on the wrist.

Piezoelectret Based Energy Harvesting From Human Body Motions With Respect to Implementation of Self-Powering Wearable Devices

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2021/volume/85499

ASME 2021 Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS2021)

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