Less can be more. Holes in polymers lead to a new paradigm of piezoelectric materials for electret transducers

Gerhard, Reimund

doi:10.1109/tdei.2002.1038668

Cited by 281 publications

(152 citation statements)

References 64 publications

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“…Another type of polymer that has received less attention is PP (polypropylene) for electret-based energy harvesting [11] using the effective thickness mode (33-mode). The formation of PP films involves a process in which biaxial stretching results in lens-like voids in the material due to initially compound small particles such as minerals (which act as nuclei for void creation) prior to corona discharging [12,13]. There has been growing interest [11,[14][15][16] in the use of PP films for energy harvesting as an alternative to PVDF [8][9][10] and other soft materials such as dielectric elastomers [17,18] and ionic polymer-metal composites [19,20].…”

Section: Introductionmentioning

confidence: 99%

Figure of merit comparison of PP-based electret and PVDF-based piezoelectric polymer energy harvesters

et al. 2016

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The harvesting of mechanical strain and kinetic energy has received great attention over the past two decades in order to power wireless electronic components such as those used in passive and active monitoring applications. Piezoelectric ceramics, such as PZT (lead zirconate titanate), constitute the most commonly used electromechanical interface in vibration energy harvesters. However, there are applications in which piezoelectric ceramics cannot be used due to their low allowable curvature and brittle nature. Soft polymer PVDF (polyvinylidene fluoride) is arguably the most popular non-ceramic soft piezoelectric energy harvester material for such scenarios. Another type of polymer that has received less attention is PP (polypropylene) for electret-based energy harvesting using the thickness mode (33-mode). This work presents figure of merit comparison of PP versus PVDF for off-resonant energy harvesting in thickness mode operation, revealing substantial advantage of PP over PVDF. For thicknessmode energy harvesting scenarios (e.g. dynamic compression) at reasonable ambient vibration frequencies, the figure of merit for the maximum power output is proportional to the square of the effective piezoelectric strain constant divided by the effective permittivity constant. Under optimal conditions and for the same volume, it is shown that PP can generate more than two orders of magnitude larger electrical power as compared to PVDF due to the larger effective piezoelectric strain constant and lower permittivity of the former.

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Section: Introductionmentioning

confidence: 99%

Figure of merit comparison of PP-based electret and PVDF-based piezoelectric polymer energy harvesters

et al. 2016

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“…FERROELECTRET is a thin and flexible cellular polymer foam that can store charges in its internal voids [1][2][3][4], thus being able to generate electric pulse under mechanical deformation such as compression and bending [5][6]. Due to its high piezoelectric voltage constant g 33 [7], ferroelectret has already been used extensively in sensor applications, such as blood pressure pulse transducer [8], touch sensor [9], ultrasonic transducer [10], prosthetic skin [11], and accelerometer [12].…”

Section: Introductionmentioning

confidence: 99%

“…Due to its high piezoelectric voltage constant g 33 [7], ferroelectret has already been used extensively in sensor applications, such as blood pressure pulse transducer [8], touch sensor [9], ultrasonic transducer [10], prosthetic skin [11], and accelerometer [12]. Among the ferroelectret materials that have been developed, cellular polypropylene (PP) is one of the most researched [2][3][4][5][6], and being one of the first commercialized ferroelectrets [13][14][15]. Charged cellular PP exhibits a high piezoelectric charge constant d 33 , which is comparable to commercial PZT [7].…”

Section: Introductionmentioning

confidence: 99%

Energy harvesting study on single and multilayer ferroelectret foams under compressive force

Luo

Zhu

Shi

et al. 2015

IEEE Trans. Dielect. Electr. Insul.

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Cellular polypropylene (PP) ferroelectret is a thin and flexible cellular polymer foam that generates electrical power under mechanical force. This work investigates single and multilayer ferroelectret PP foams and their potential to supply energy for human-bodyworn sensors. Human foot-fall is emulated using an electrodynamic instrument, allowing applied compressive force and momentum to be correlated with energy output. Peak power, output pulse duration, and energy per strike is derived experimentally as a function of force and momentum, and shown to be a strong function of external load resistance, thus providing a clear maximum energy point. The possibility of increasing pulse time and reducing voltage to CMOS compatible levels at some expense of peak power is shown. To further increase the output power, multilayer ferroelectret is presented. The synchronized power generation of each layer is studied and illustrated using simulation, and results are supported by experiments. Finally, the energy output of single-layer and multi-layer ferroelectrets are compared by charging a capacitor via a rectifier. A ten-layer ferroelectret is shown to have charging ability 29.1 times better than that of the single-layer ferroelectret. It demonstrates energy output that is capable of powering the start-up and transmission of a typical low-power wireless sensor chipset.

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“…15 Because of the lens-like air voids and the low stiffness, cellular PP can be rendered highly piezoelectric by corona charging. [7][8][9] In the past, pressure expansion methods were developed 16,17 to increase the piezoelectric d 33 -coefficients mainly by decreasing Young's modulus of the cellular films. These methods not only affect the size of Young's modulus but also its frequency response.…”

Section: Cellular Polypropylene Ringmentioning

confidence: 99%

“…Some years ago, microphones based on charged cellular polymers, later on referred to as piezoelectret microphones 5,6 were introduced that are based on ferroelectret 7,8 or, sometimes also called, piezoelectret films. 9 In these microphones, the sound pressure acts, for lower frequencies, uniformly on one or both sides of the piezoelectret films; this results in a uniform thickness change everywhere on the films.…”

Section: Introductionmentioning

confidence: 99%

Electret microphones with stiff diaphragms

Hillenbrand

Haberzettl

Sessler

2013

The Journal of the Acoustical Society of America

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Electret microphones with stiff plates instead of flexible diaphragms are described. The stiff plate and a backplate, separated by a soft cellular polymer spacer ring, yield a capacitance that is varied by the incoming sound wave; thus a voltage change in the plates is induced. Various such plate microphones were built and characterized. Sensitivities of more than 10 mV/Pa and equivalent noise levels of 23 dB(A) are obtained. An analytical model for the sensitivity of plate microphones was developed. Advantages of the plate microphones are high mechanical robustness, low harmonic distortion, and no risk of membrane collapse.

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Less can be more. Holes in polymers lead to a new paradigm of piezoelectric materials for electret transducers

Cited by 281 publications

References 64 publications

Figure of merit comparison of PP-based electret and PVDF-based piezoelectric polymer energy harvesters

Figure of merit comparison of PP-based electret and PVDF-based piezoelectric polymer energy harvesters

Energy harvesting study on single and multilayer ferroelectret foams under compressive force

Electret microphones with stiff diaphragms

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