Metallisation of Textiles and Protection of Conductive Layers: An Overview of Application Techniques

Abstract

The rapid growth in wearable technology has recently stimulated the development of conductive textiles for broad application purposes, i.e., wearable electronics, heat generators, sensors, electromagnetic interference (EMI) shielding, optoelectronic and photonics. Textile material, which was always considered just as the interface between the wearer and the environment, now plays a more active role in different sectors, such as sport, healthcare, security, entertainment, military, and technical sectors, etc. This expansion in applied development of e-textiles is governed by a vast amount of research work conducted by increasingly interdisciplinary teams and presented systematic review highlights and assesses, in a comprehensive manner, recent research in the field of conductive textiles and their potential application for wearable electronics (so called e-textiles), as well as development of advanced application techniques to obtain conductivity, with emphasis on metal-containing coatings. Furthermore, an overview of protective compounds was provided, which are suitable for the protection of metallized textile surfaces against corrosion, mechanical forces, abrasion, and other external factors, influencing negatively on the adhesion and durability of the conductive layers during textiles' lifetime (wear and care). The challenges, drawbacks and further opportunities in these fields are also discussed critically.

Keywords: coatings techniques; conductive textiles; durability; e-textiles; metallization; protective coatings.

Figure 1

Schematic presentation of different metallization techniques to obtain electrically conductive textiles, namely, electroless plating (reprinted with permission from Ref. [6] Copyright 2021 Elsevier), electrochemical deposition (reprinted with permission from Ref. [27] Copyright 2021 Springer Nature), physical and chemical vapor deposition, thermal and plasma spray coating (reprinted with permission from Ref. [28] Copyright 2021 MDPI), inkjet (reprinted with permission from Ref. [29] Copyright 2021 Springer Nature), and screen-printing (adapted from Ref. [30]).

Figure 2

(a) Schematic diagram of screen printing in a cross-sectional view (reprinted with permission from Ref. [46] Copyright 2021 Elsevier); (b) a SEM image of printed Ag tracks on textiles (adapted from Ref. [47]); (c); schematic of textile patch antennas and their two-way Bluetooth communication system, using textile and commercial antennas (reprinted with permission from Ref. [48] Copyright 2021 John Wiley and Sons); (d) flexible screen-printed electrode on textile using Ag ink and a layer of graphene oxide (GO), and a schematic visualization cross-section showing the affinity assay for influenza (reprinted with permission from Ref. [35] Copyright 2021 IOP Publishing).

Figure 3

(a) Schematic presentation of inkjet printing of conductive Ag ink on textiles (reprinted with permission from Ref. [37] Copyright 2021, American Chemical Society); (b) presentation of a drop of Ag ink distribution on fibers with different diameters (reprinted with permission from Ref. [37] Copyright 2021, American Chemical Society); (c) SEM images of Ag inkjet printing, together with a combination of cellulose nanofibrils/glycerol on woven cotton fabric (reprinted with permission from Ref. [50] Copyright 2021, American Chemical Society); (d) XCT 3D reconstruction images of Ag (blue-green) deposited on polyester fabric (grey) with an increasing number of layers (reprinted with permission from Ref. [51] Copyright 2021 American Chemical Society); (e) textile heating actuators—computer designed patterns and thermal images of Ag inkjet printing PP spun non-woven textile (reprinted with permission from Ref. [52] Copyright 2021, Elsevier); and (f) digital moisture sensor signals recorded from the inkjet printing part on the fabric (reprinted with permission from Ref. [50] Copyright 2021, American Chemical Society).

Figure 4

(a) Electroless Cu plated samples: the whole surface, pattern, and corresponding optical microscopy image; (b) SEM images of electroless Cu plated sample: longitudinal view and cross-sectional; (c) illustration of electroless plating process (reprinted with permission from Ref. [69] Copyright 2021, American Chemical Society); (d) sheet resistance during periodic stretching and releasing test at different strain levels, using a wearable strain sensor prepared by silver plated cotton/spandex blended fabric (reprinted with permission from Ref. [23] Copyright 2021, Elsevier); (e) the scheme of an EMI shielding mechanism of Ni-W-P/PANI/PI fabric (reprinted with permission from Ref. [61] Copyright 2021, Elsevier).

Figure 5

(a) Schematic electrodeposition process with a three-electrode system (reprinted with permission from Ref. [98] Copyright 2021, John Wiley and Sons); (b) average resistance values of differently electroplated conductive threads (reprinted with permission from Ref. [97] Copyright 2021, Springer Nature Limited); (c) working principle of the thread sensor that detects chloride ions, pH and sweat simultaneously (reprinted with permission from Ref. [97] Copyright 2021, Springer Nature Limited); (d) SEM image of PET coated uniformly with amorphous NiWO₄ (adapted from Ref. [89]); (e) SEM of Cu NP-coated PET knitted fabric and corresponding conductivity test (adapted from Ref. [99]).

Figure 6

(a) Basic mechanism of the magnetron sputtering process; (b) relative change of resistance of Ag coated Cordura subjected to cyclic bending, and corresponding microscopic and SEM images after 10,000 bending cycles (reprinted with permission from Ref. [107] Copyright 2021, Springer); (c) magnetron sputtered Cu transmission lines on polypropylene nonwoven and responsible SEM images: longitudinal view and cross-section (reprinted with permission from Ref. [110] Copyright 2021, Łukasiewicz Research Network—Institute of Biopolymers and Chemical Fibres); (d) monitoring the finger motions by Ag/G-coated cotton: rotation and bending (adapted from Ref. [111]); (e) sheet resistance of Ag/polypyrrole-coated cotton as a function of sputtering time and corresponding SEM at 10 min (adapted from Ref. [115]).

Figure 7

(a) Schematic of the thermal spraying (adapted from Ref. [122]); (b) scheme of the spray coating process of previously fabricated MXene to attain multifunctional electrically conductive cotton fabric (reprinted with permission from Ref. [127] Copyright 2021, American Chemical Society); (c) temperature distribution of the wearable heater attached on a wrist and glove (adapted from Ref. [127]); (d) SEM morphology of different cellulose yarns spray coated with the conductive Mxene flakes (reprinted with permission from Ref. [128] Copyright 2021, John Wiley and Sons); (e) SEM of ZnO and GO-coated cotton fabric using different spray coating cycles for EMI shielding (reprinted with permission from Ref. [129] Copyright 2021, Elsevier).