Title
Flexible Piezoelectric Touch Sensor by Alignment of Lead-Free Alkaline Niobate Microcubes in PDMS
Author
Deutz, D.B.
Mascarenhas, N.T.
Schelen, J.B.J.
de Leeuw, D.M.
van der Zwaag, S.
Groen, P.
Publication year
2017
Abstract
A highly sensitive, lead-free, and flexible piezoelectric touch sensor is reported based on composite films of alkaline niobate K0.485Na0.485Li0.03NbO3 (KNLN) powders aligned in a polydimethylsiloxane (PDMS) matrix. KNLN powder is fabricated by solid-state sintering and consists of microcubes. The particles are dispersed in uncured PDMS and oriented by application of an oscillating dielectrophoretic alignment field. The dielectric constant of the composite film is almost independent of the microstructure, while upon alignment the piezoelectric charge coefficient increases more than tenfold up to 17 pC N−1. A quantitative analysis shows that the origin is a reduction of the interparticle distance to under 1.0 μm in the aligned bicontinuous KNLN chains. The temperature stable piezoelectric voltage coefficient exhibits a maximum value of 220 mV m N−1, at a volume fraction of only 10%. This state-of-the-art value outperforms bulk piezoelectric ceramics and composites with randomly dispersed particles, and is comparable to the values reported for the piezoelectric polymers polyvinylidenefluoride and its random copolymer with trifluoroethylene. Optimized composite films are incorporated in flexible piezoelectric touch sensors. The high sensitivity is analyzed and discussed. As the fabrication technology is straightforward and easy to implement, applications are foreseen in flexible electronics such as wireless sensor networks and biodiagnostics.
Subject
Nano Technology
HOL - Holst HOL - Holst
TS - Technical Sciences
Electronics
Industrial Innovation
Piezoelectric sensors
Alkaline niobate
PDMS
KNLN
Piezoelectric ceramics
Piezoelectric composites
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http://resolver.tudelft.nl/uuid:d6ef4b11-78fe-4139-ae1c-a3f08c1e8ad5
DOI
https://doi.org/10.1002/adfm.201700728
TNO identifier
781150
Source
Advanced Functional Materials, 27
Article number
1700728
Document type
article