Piezoelectric properties of nonuniform electrets

Kacprzyk, R.; Motyl, E.; Gajewski, Juliusz B.; Pasternak, A.

doi:10.1016/0304-3886(95)00034-8

Cited by 56 publications

(19 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The porous fluoropolymer film used in this study was made of a nonwoven fabric [20][21][22]. We used an electrospinning method involving the spraying of a spinning solution from a nozzle under an electric field to produce a direct nonwoven fabric from a resin solution [20][21][22].…”

Section: Sample Fabricationmentioning

confidence: 99%

Piezoelectret sensor made from an electro-spun fluoropolymer and its use in a wristband for detecting heart-beat signals

Tajitsu

2015

IEEE Trans. Dielect. Electr. Insul.

View full text Add to dashboard Cite

We developed a new wearable wristband-type piezo-sensor for detecting the pressure signals from the heartbeat. A piezoelectric porous electret made from electro-spun poly(tetrafluoroethylene) (PTFE) was used as the piezo-sensor material. This lightweight and flexibile porous PTFE electret exhibited high and stable piezoelectricity, enabling the realization of a piezo-sensor in a new wearable wristband-type instrument. Using the instrument, we observed a signal with detection accuracy equal to that of an electrocardiogram.

show abstract

Section: Sample Fabricationmentioning

confidence: 99%

Piezoelectret sensor made from an electro-spun fluoropolymer and its use in a wristband for detecting heart-beat signals

Tajitsu

2015

IEEE Trans. Dielect. Electr. Insul.

View full text Add to dashboard Cite

show abstract

“…Further work has been conducted where PTFE foam layers have been incorporated into multilayered sandwiches (26,39) , i.e. double layer sandwiches of one hard and one soft layer with an interface charge layer between them (40,41,42) . If two or more separate foams are to be assembled into such a sandwich, then air pockets have to be avoided.…”

Section: Materials Characteristicsmentioning

confidence: 99%

Ceramic Based Intelligent Piezoelectric Energy Harvesting Device

Patel¹

2011

Advances in Ceramics - Electric and Magnetic Ceramics, Bioceramics, Ceramics and Environment

View full text Add to dashboard Cite

“…The relatively low piezoelectric d 33 -coefficient, of about 4 pC/N was obtained due to the different elasticity of the polymer layers. [2] In 1996, electromagnetic transducer coefficients of 30 pm/V in corona-charged cellular i-PP films were detected and such films were utilised for first applications. [3] A few years later, those effects were characterised by models of the cellular materials.…”

mentioning

confidence: 99%

Piezoelectricity of Cellular Polypropylene Films Expanded by a Dichlormethane Evaporation Process

et al. 2008

View full text Add to dashboard Cite

Piezoelectric effects in polar polymers are known for over 30 years, especially in b-PVDF. [1] In 1995, weak piezoelectric effects were also found in multilayer polymer films. Kacprzyk succeeded in verifying those piezoelectric effects in duallayer dielectrics, on basis of polypropylene/polyurethaneelectret sandwich systems after a corona charging. The relatively low piezoelectric d 33 -coefficient, of about 4 pC/N was obtained due to the different elasticity of the polymer layers. [2] In 1996, electromagnetic transducer coefficients of 30 pm/V in corona-charged cellular i-PP films were detected and such films were utilised for first applications. [3] A few years later, those effects were characterised by models of the cellular materials. [4][5][6][7] Through the corona charging [8] of thin cellular polypropylene films, with very high electric voltages, breakdowns in the individual pores are caused by micro plasma discharges. [7,9] After the electric breakdown the space charges are deposited at the interfaces of the cells. By applying a mechanical tension, the charged pores act as macroscopic dipoles; therefore the films show, with appropriately fixed electrodes on the surfaces of the film, a clearly measurable piezoelectric activity, since the system reacts to this change of the polarisation with a compensation current in the electrodes. [4,[10][11][12][13] The accuracy of a piezoelectric model was verified through the good correlation of the calculated and measured d 33 -coefficients. [14,15] Such cellular polypropylene films show an anisotropic, lentoid cavity structure. [16,17] As the charged cellular films were applied in electro mechanical transducers, such as acoustic sensors, [16,17] their production processes and the charging methods were further investigated. Based on this, other influence factors on the piezoelectric activity, such as the effect of heat treatment [5,10] and UV radiation with short wave length, [18,19] were studied.Recently some articles concerning the optimising of the piezoelectric activity of cellular films by using gas-expansion processes, were published. [20][21][22] The role of geometric shape of the cells, [23,24] and the influence of the gas in the cells, during the charging, [25] were closely studied. The development of expansion processes under high pressure for achieving large piezoelectric coefficients is one of the main focuses in today's research. [20][21][22] In the present paper, a new method for expanding stretched cellular i-PP films [26,27] is introduced. This process consists of three steps. Firstly, the cellular i-PP films with small cavities are saturated with dichlormethane (DCM). Then the DCM is abruptly evaporated at an elevated temperature of 120°C to expand the cavities inside the films. Finally, the expanded film samples are quenched in liquid nitrogen, to fix the cell structure. Experimental MaterialsAn isotactic polypropylene reactor powder, supplied by Borealis Linz, Austria, was used for the investigations. The weight average molecular weight was 425.000 ...

show abstract

Piezoelectric properties of nonuniform electrets

Cited by 56 publications

References 2 publications

Piezoelectret sensor made from an electro-spun fluoropolymer and its use in a wristband for detecting heart-beat signals

Piezoelectret sensor made from an electro-spun fluoropolymer and its use in a wristband for detecting heart-beat signals

Ceramic Based Intelligent Piezoelectric Energy Harvesting Device

Piezoelectricity of Cellular Polypropylene Films Expanded by a Dichlormethane Evaporation Process

Contact Info

Product

Resources

About