Title
Macro-dipoles in soft/hard expanded-polytetrafluoroethylene + fluoroethylenepropylene (ePTFE + FEP) fluoropolymer-film systems for high-output piezoelectric ferroelectret-transducer applications
Author
Wang, Ningzhen (Beijing Forestry University; University of Connecticut)
Baferani, Mohamadreza Arab (University of Connecticut)
Daniels, Robert (University of Connecticut)
Wu, Chao (University of Connecticut)
Huo, Jindong (University of Connecticut)
van Turnhout, J. (TU Delft Team Erik Offerman) 
Sotzing, Gregory A. (University of Connecticut)
Gerhard, Reimund (University of Potsdam)
Cao, Yang (University of Connecticut)
Date
2024
Abstract
Multi-layer ferroelectrets consisting of fluoroethylenepropylene (FEP) copolymer and open-porous expanded polytetrafluoroethylene (ePTFE) films exhibit stable internal electret charges, high piezoelectric coefficients and heat resistance, making them promising candidates for wearable sensors or nanogenerators in body-area networks. Here, three- and five-layer (FEP/ePTFE/FEP and FEP/ePTFE/FEP/ePTFE/FEP) ferroelectret stacks were laminated and poled in a corona discharge. The resulting charge distributions were measured by use of the pulsed electro-acoustic (PEA) method and revealed that charges of opposite polarity were trapped at the interfaces between the FEP and ePTFE layers. Thus, the existence of one macro-dipole in the three-layer structure and of two macro-dipoles in the five-layer structure was directly shown for the first time. Moreover, electric-displacement-versus-electric-field (D-E) loops revealed that remnant polarization is given by the number of macro-dipoles in the respective stack. Due to the addition of the macro-dipoles, the piezoelectric d 33 coefficient of the FEP/ePTFE/FEP/ePTFE/FEP stack reaches 200 pC/N even under a potentially non-uniform compression of the soft ePTFE layers. The results should be useful for a better understanding and a performance optimization of ferroelectrets in self-powered intelligent devices.
Subject
charge distribution
charge-spring model
ePTFE + FEP ferroelectret
piezoelectricity
To reference this document use:
http://resolver.tudelft.nl/uuid:91285ba8-2d88-442a-a3bb-364c0718947b
DOI
https://doi.org/10.1088/1361-6463/ad1a84
Embargo date
2024-07-11
ISSN
0022-3727
Source
Journal of Physics D: Applied Physics, 57 (14)
Part of collection
Institutional Repository
Document type
journal article
Rights
© 2024 Ningzhen Wang, Mohamadreza Arab Baferani, Robert Daniels, Chao Wu, Jindong Huo, J. van Turnhout, Gregory A. Sotzing, Reimund Gerhard, Yang Cao