Improvements in energy harvesting capabilities by using different shapes of piezoelectric bimorphs

Abstract

The small amount of power needed by microelectronic devices opens up the possibility to convert part of the vibration energy present in the environment into electrical energy, using several methods. One such method is to use piezoelectric material as an additional layer in cantilever beams to harvest vibration energy for self-powered sensors. The geometry of a piezoelectric cantilever beam will greatly affect its vibration energy harvesting ability. Tapering and changing the configuration as ways to increase the generated output power of cantilever piezoelectric energy harvesters have gained popularity in recent years. In this work vibration energy harvesting via piezoelectric resonant bimorph cantilevers is studied and new designs for obtaining optimal piezoelectric energy harvesters are suggested. This paper deduces a very precise and simple analytical formula that can be used as a rule of thumb for calculating the resonant frequency of bimorph trapezoidal V-shaped cantilevers using the Rayleigh–Ritz method. This analytical formula is then analyzed using MATLAB as well as finite element methods and validated by ABAQUS simulation. Also, mathematical derivations for the output voltage of bimorph piezoelectric energy harvesters are presented and validated by simulation and experimental results. These formulas provide a new perspective that, among all the bimorph trapezoidal V-shaped cantilever beams with uniform thickness, the bimorph triangular tapered cantilever can lead to the highest resonant frequency and therefore maximum sensitivity, and by increasing the ratio of the trapezoidal bases the sensitivity decreases. Also, the output voltage and strain distribution show that the triangular cantilever has the highest efficiency and power density.

Design, Modeling, and Simulation of Two‐Piece Trapezoidal Piezoelectric Devices for Sensing and Energy Harvesting

“…It is shown that increasing the width W 2 (at free end) lowers the resonance frequency, which agrees with our results. It was also shown that the trapezoidal shape generates higher voltage compared to the simple rectangular cantilever beam bimorph which matches our findings in previous works [6,12]. In this paper, we explore a unique design of 2-piece trapezoidal shaped piezoelectric bimorph to understand its effects on harvested power, power density, and bandwidth.…”

Energy Harvesting Research: The Road from Single Source to Multisource

“…Apart from the tuning of the material composition, the rest of the piezoelectric energy harvesting research has focused on the structural design and optimization for different applications. The most popular structures used in piezoelectric energy harvesters include cantilever, stack cymbal configuration, diaphragm configuration, and shear mode configuration . The cantilever structure is suitable for low input force, small acceleration, and mid‐high frequencies (tens of Hz or above), but it allows large amplitude/deformation.…”

Research of piezoelectric energy harvesting systems based on cantilevers with irregular cross-sections

“…It can be found numerous reports on investigations related to optimization and application of different shapes and vibration modes of piezoelectric cantilevers which can be used for energy harvesting (Thein and et al 2016;Hosseini and Hamedi, 2015;Mohamed and et al 2016;Žižys and et al 2015;Ostaševičius and et al 2015). Moreover, numerous models were developed in order to predict mechanical and electrical characteristics of cantilevers with different shapes Erturk and Inman, 2009;Deitl and et al 2010).…”