Processing and Electrical Response of Fully Polymer Piezoelectric Filaments for E-Textiles Applications

Abstract

This paper describes the production and characterization of novel geometries for piezoelectric products with a large potential in the design and implementation of flexible sensors produced at low cost and high rates. In particular, the filament geometry, appropriate for integration into textiles, is analyzed. Piezoelectric filaments producing electrical signals under bending or traction loads, thus acting as mechanical sensors, have been produced and tested, and are presented in this paper.

Piezoelectric Melt-Spun Textile Fibers: Technological Overview

“…Wide angle, X-ray diffraction (XRD) [65,66] Tensile strength tests to determine the Young modulus of the fibers [65] Fourier transform infrared spectroscopy (FTIR) [66,67] Determination of tensile strength at break [67,68] Measurement of the electric conductivity [67] Measurement of the electromechanical response (Voltage response of the filaments during mechanical stimulation [tensile strain]) [67] Microscopy [67] Determination of the electromechanical response of the filaments (voltage produced due to mechanical stimulation (vibration, elongation) [68] The subject of the research by Silva et al [66] (recycled PVDF filaments) was unique in the literature reviewed. The results of several consecutive processing cycles on piezoelectric PVDF samples showed that all the parameters that were studied were unaffected or only very slightly affected by up to nine processing cycles suggesting that PVDF recycling was feasible regarding its electroactive properties (Table 4).…”

“…The test specimens comprised a piezoelectric cable obtained from a two-layer coextruded filament, comprising an internal semi-conductive electrode (carbon black-filled polypropylene compound and a carbon nanotube-based compound) and a PVDF layer, coated with a thin layer of a Piezoelectricity -Organic and Inorganic Materials and Applications semi-conductive copper-based lacquer. Also in Portugal, in 2014, Rui et al [68] investigated coaxial PVDF filaments with a filament core comprising conductive PP. Ferreira et al [65] concentrated their efforts on producing coaxial piezoelectric filaments made from PVDF, as opposed to pure polymer filaments.…”

“…There are two major approaches regarding the characterization of the electromechanical response of the fibers: (i) qualitative tests that are intended to show the potential of the fibers, that is, research conducted by Nilsson et al and Kechiche et al [52,69] and (ii) measurement of the voltage produced by the fibers (or multifilament yarns or fabrics incorporating the said yarns) when they are mechanically stimulated either by tensile strain [48,67,68], impact [33,53,59], compression [50,70,71] or bending [44].…”