Planform Geometry and Excitation Effects of PVDF-Based Vibration Energy Harvesters

Jie Wang,Mostafa R A Nabawy,Andrea Cioncolini,Alistair Revell,Samuel Weigert

doi:10.3390/en14010211

Jie Wang, Mostafa R A Nabawy + Show 3 more

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https://doi.org/10.3390/en14010211

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Journal: Energies	Publication Date: Jan 3, 2021
Citations: 8	License type: CC BY 4.0

Affiliation: University of Manchester, Cairo University

Abstract

In the present paper, we report a systematic investigation of planform geometry and excitation level effects on the dynamics and power generation characteristics of polyvinylidene difluoride (PVDF)-based cantilevered vibration energy harvesters. Piezoelectric vibration energy harvesters provide a promising energy harvesting solution for widespread use of wireless sensors in remote locations. Highly flexible PVDF polymers offer resonant frequencies at suitable range for harvesting mechanical energy within low-frequency applications, though information on the efficient sizing of these devices is currently limited. We test the response of a set of eight harvesters to typical vibration sources excitation levels in the range 0.2–0.6 g. This set comprises four widths and two lengths, incrementing each time by a factor of two. The selected range of dimensions is sufficient to identify optimal power output versus width for both lengths tested. This optimal width value depends on excitation amplitude in such a way that narrower harvesters are more suited for small excitations, whereas wider harvesters perform better upon experiencing large excitations. Non-linear effects present in longer harvesters are demonstrated to significantly reduce performance, which motivates the selection of planform dimensions inside the linear range. Finally, we explore the correlation of performance with various geometric quantities in order to inform future design studies and highlight the value of using the second moment of planform area to measure harvester efficiency in terms of power density. This points towards the use of harvesters with non-rectangular planform area for optimal performance.

Highlights

Wireless sensor networks typically comprise a series of dedicated, autonomous, and spatially distributed sensor nodes to monitor physical parameters, such as temperature, pressure, humidity, sound level, chemical concentration, wind speed, etc
Tip displacement and root mean square (RMS) power output measurements are shown in Figure 4, for all harvesters, plotted as a function of the non-dimensional frequency of excitation for different amplitudes of the level of excitation
As expected, when the excitation frequency approaches the resonant frequency of the harvester, the tip displacement increases, reaching a maximum that is proportional to the amplitude of the excitation

Summary

Introduction

Wireless sensor networks typically comprise a series of dedicated, autonomous, and spatially distributed sensor nodes to monitor physical parameters, such as temperature, pressure, humidity, sound level, chemical concentration, wind speed, etc. They are currently used in everyday life across a broad range of applications including industrial process monitoring and control [1,2,3], health monitoring and damage detection in machines/structures [4,5], air pollution and water quality monitoring [6,7,8,9], and wildfire detection and natural disaster prevention [10,11,12]. For small sensors with modest power requirements there is an opportunity to replace these batteries by energy harvesting modules, which generate electrical power from ambient energy sources; whether this is mechanical, thermal, or electromagnetic in nature

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