Elasticity investigation of thin cellular structure films for piezoelectric sensors
ISSN: 0260-2288
Article publication date: 23 December 2021
Issue publication date: 8 March 2022
Abstract
Purpose
This paper aims to present the details of isotactic polypropylene (it-PP) films with a cellular structure (air-cavities) dedicated to pressure sensors. The polymer composites (thin films enriched with 5 and 10 wt% of mineral fillers as Sillikolloid P 87 and glass beads) should exhibit suitable structural elasticity within specific stress ranges. After the deformation force is removed, the sensor material must completely restore its original shape and size.
Design/methodology/approach
Estimating the stiffness tensor element (C33) for polymer films (nonpolar space-charge electrets) by broadband resonance ultrasound spectroscopy is a relatively simple method of determining the safe stress range generated in thin pressure sensors. Therefore, ultrasonic and piezoelectric studies were carried out on four composite it-PP films. First, the longitudinal velocity (vL) of ultrasonic waves passing through the it-PP film in the z-direction (thickness) was evaluated from the ω-position of mechanical resonance of the so-called insertion loss function. In turn, the d33 coefficient was calculated from accumulated piezoelectric charge density response to mechanical stress.
Findings
Research is at an early stage; however, it can be seen that the mechanical orientation of the it-PP film improves its piezoelectric properties. Moreover, the three-year electric charge stability of the it-PP film seems promising.
Originality/value
Ultrasonic spectroscopy can be successfully handled as a validation method in the small-lot production of polymer films with the air-cavities structure intended for pressure sensors. The structural repeatability of polymer films is strongly related to a homogeneous distribution of the electric charge on the electret surface.
Keywords
Acknowledgements
This research was supported by the National Science Centre, Poland (grant No. 2015/17/B/ST8/03396). The authors would like to express their deepest gratitude to Andrzej Cichocki from Research Group of LTCC Technology and Printed Electronics, Łukasiewicz–Institute of Micro-electronics and Photonics, for his assistance during the piezoelectric experiment and valuable discussion.
Citation
Klimiec, E., Zachariasz, P., Kaczmarek, H., Królikowski, B. and Mackiewicz, S. (2022), "Elasticity investigation of thin cellular structure films for piezoelectric sensors", Sensor Review, Vol. 42 No. 2, pp. 204-213. https://doi.org/10.1108/SR-07-2021-0220
Publisher
:Emerald Publishing Limited
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