Multilayer piezoelectret foam stack for vibration energy harvesting

Abstract

Electronic devices are high-demand commodities in today’s world, and such devices will continue increasing in popularity. Currently, batteries are implemented to provide power to these devices; however, the need for battery replacement, their cost, and the waste associated with battery disposal present a need for advances in self-powered technology. Energy harvesting technology has great potential to alleviate the drawbacks of batteries. In this work, a novel piezoelectret foam material is investigated for low-level vibration energy harvesting. Specifically, piezoelectret foam assembled in a multilayer stack configuration is explored. Modeling and experimentation of the stack when excited in compression at low frequencies are performed to investigate piezoelectret foam for multilayer energy harvesting. An equivalent circuit model derived from the literature is used to model the piezoelectret stack. Two 20-layer prototype devices and one 40-layer prototype device are fabricated and experimentally tested via harmonic base excitation. Electromechanical frequency response functions between input acceleration and output voltage are measured experimentally. Modeling results are compared to experimental measurements to assess the fidelity of the model near resonance. Finally, energy harvesting experimentation in which the device is subject to harmonic base excitation at the fundamental natural frequency is conducted to determine the ability of the stack to successfully charge a capacitor. For a 20-layer stack excited at 0.5 g, a 100-µF capacitor is charged to 1.45 V in 15 min, and produces a peak power of 0.45 µW. A 40-layer stack is found to charge a 100-µF capacitor to 1.7 V in 15 min when excited at 0.5 g, and produce a peak power of 0.89 µW.

Long-Term Stability of Ferroelectret Energy Harvesters

“…The natural frequency is a function of the harvester effective mass m eq and effective stiffness k. We hypothesize that the response of ferroelectric harvesters will continue to follow that of piezoelectric harvesters over the long-term as it has been shown to do over the short-term by Pondrom et al [6,20] and Ray et al [15]. To test this hypothesis, we compare their mathematical model to our experimental results over the test period.…”

“…Pondrom et al [19] proposed and validated a model for PP energy harvesters under harmonic base exctiation. Ray et al [15] independently validated this model. Luo et al [18] proposed a model for PP energy harvesters under impulse excitation.…”

“…Anton et al [5] found that the stiffness and strength of thin PP sheets were significantly different in the two planar directions, possibly due to asymmetries in biaxial stretching during manufacturing. Ray et al [15] found that the piezoelectric charge constant d 33 drops gradually with the excitation frequency up to 1-10 kHz. Comparative analysis of the PP energy harvesters are depicted in Table 1.…”

“…Comparative analysis of the PP energy harvesters are depicted in Table 1. -400 4 8 80 27 @ 1.0 g Ray [15] 37.8 90.6 10.08 40 0.89 1000 @ 0.5 g Luo [17] 295 -42 80 100 80,000 Luo [18] 295 -42 1 3.07 80,000…”

“…Sessler et al [16] were able to generate 80 µW output power with a larger-area radiation better performing (higher d 33 ) cross-linked multi-layer PP energy harvester. On the other hand, Ray et al [15] generated 0.45 µW with a 20-layer PP harvester because of a lower d 33 film. Luo et al [17,18] harvested energy from the impact of body weight during the heel strike stage of walking sing multi-layer PP harvesters.…”