Controlled inflation of voids in cellular polymer ferroelectrets: Optimizing electromechanical transducer properties

Wegener, Michael; Wirges, Werner; Gerhard, Reimund; Dansachmüller, M.; Schwödiauer, Reinhard; Bauer‐Gogonea, S.; Bauer, Siegfried; Paajanen, Mika; Minkkinen, Hannu; Raukola, J.

doi:10.1063/1.1641171

Cited by 135 publications

(124 citation statements)

References 12 publications

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“…It is very soft in the thickness direction, with Young's modulus in the order of 1MPa [16][17]. Due to its high d 33 and small Young's modulus, PP is able to generate large electric pulse under compression force.…”

Section: Introductionmentioning

confidence: 99%

“…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]. It is very soft in the thickness direction, with Young's modulus in the order of 1MPa [16][17].…”

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].…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…It has to be taken into account that there is an error due to the fact that current measurements do not reach the zero level before the sample fusion. Thus the parameters of the Arrhenius equation can be obtained according to equation (4).…”

Section: Tsdc Measuring Resultsmentioning

confidence: 99%

“…Later different authors have proposed a structural modification of the material [4][5] to improve its piezoelectric properties.…”

Section: Introductionmentioning

confidence: 99%

Characterisation and optimisation of the d ₃₃ coefficient of cellular PP films

Braña

Llovera-Segovia²,

Mor³

et al. 2017

IET Science, Measurement & Technology

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Piezoelectric polymer cellular films with silver electrodes are made from a PP film activated by corona discharge. This cellular polymer is characterized by its high piezoelectric d33 coefficients in comparison with piezoelectric ceramics and other polymers like PVDF. One of the advantages is their malleability and shape ability in different kinds of forms. Our work presents the optimization of the activation process and the results of films characterization. All the samples are made from available PP film modified by a thermal biaxial stretching. d33 constant was measured by a quasi-static method and laser interferometry giving similar results. Transducer coefficients of about 700 pC/N were obtained. An approximation of the surface charge density in the polymer voids was obtained with a mathematical model. Thermal stability was checked by thermally stimulated depolarization currents (TSDC) showing a relationship between TSDC and d33 constant. Time stability was determined with more than one year old samples. Finally, the resonance frequency was obtained from interferometry measurement.

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Piezoelectric Polyethylene Terephthalate (PETP) Foams – Specifically Designed and Prepared Ferroelectret Films

2005

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Detailed knowledge about the essential properties required for piezoelectric polymer-electret foams (or ferroelectrets) [1,2] is exploited in the design and the preparation of cellular polyethylene terephthalate (PETP) electret films with piezoelectric properties. The relevant relationships between structural, elastic and piezoelectric properties had been established previously for polypropylene (PP) ferroelectrets and could be successfully employed in the present demonstration of the novel ferroelectret polymer PETP.The piezoelectric properties of ferroelectrets are based on the quasi-permanent internal electric charging of the cellular structure with charge layers of opposite polarity on void surfaces that face each other. Due to the bipolar charging, the centrosymmetry of the polymer foam is broken and macroscopic electric dipoles are formed. In addition, the voids must deform and the effective dipole moments change under mechanical stress. So far, because of the availability of highquality cellular PP films, PP has been the ºworkhorseº of ferroelectret research and development.In PP, the combination of a relatively soft structure (low elastic stiffness) with internally trapped bipolar charges yields a high piezoelectric coefficient in the film-thickness direction. Typically, PP ferroelectret films show direct and inverse piezoelectric d 33 coefficients of several hundred pC/N (or pm/V). For cellular PP films, the preparation, the optimization of the cellular structure by means of controlled inflation, the electrical charging through internal micro-plasma discharges, and the charge storage in deep traps are well understood. [3±10] Furthermore, piezoelectric cellular PP films are already implemented in several applications. [2] There is, however, an essential requirement that PP ferroelectrets do not meet: The thermal stability of the currently available piezoelectric cellular PP films is limited to around 60 to 70 C, depending on the chosen annealing treatment. [11,12] Here, more stable materials are clearly needed for most applications. Furthermore, the ferroelectret concept should be confirmed with independently developed polymer foams that exhibit similar piezoelectric behavior.Here, we investigate PETP films that are already produced in industry on a large scale and that offer chances to prepare ferroelectret films of high quality and to achieve slightly better thermal (and temporal) stabilities than the existing PP ferroelectrets.Recently, the dependence of the piezoelectric response on the elastic stiffness and on the void structure was established for cellular PP films. [7,13] In summary, the inversely U-shaped behavior schematically shown in Figure 1 is observed. Films with small (or low) voids are relatively stiff and therefore show only low piezoelectricity. The controlled increase of the void height by means of inflation [7±9] decreases the elastic stiffness and increases the piezoelectric activity until an optimal foam structure is obtained. For cellular PP films, a minimal elastic COMMUNICATI...

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Controlled inflation of voids in cellular polymer ferroelectrets: Optimizing electromechanical transducer properties

Cited by 135 publications

References 12 publications

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

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

Characterisation and optimisation of the d ₃₃ coefficient of cellular PP films

Piezoelectric Polyethylene Terephthalate (PETP) Foams – Specifically Designed and Prepared Ferroelectret Films

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Controlled inflation of voids in cellular polymer ferroelectrets: Optimizing electromechanical transducer properties

Cited by 135 publications

References 12 publications

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

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

Characterisation and optimisation of the d 33 coefficient of cellular PP films

Piezoelectric Polyethylene Terephthalate (PETP) Foams – Specifically Designed and Prepared Ferroelectret Films

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Product

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Characterisation and optimisation of the d ₃₃ coefficient of cellular PP films