Nanotechnology-based coating techniques for smart textiles

Nanotechnology-based textile coating is a combined approach to textile engineering which mainly relies on using nanoscale materials and novel methods to produce smart finishing. Several methods have been introduced to generate smart coatings on textiles including the sol–gel technique, layer-by-layer technique, cross-linking by polymers, and thin film deposition. Nanofibre coating of different metallic and nonmetallic substrates has been intensively considered for sensory and infrastructure purposes. This chapter provides an overview of nanotechnology-based coating approaches with a detailed discussion of applications in practical and potential fields. Future trends of new types of smart coatings on textiles are also presented.

Knitted strain sensor textiles of highly conductive all-polymeric fibers

A scaled-up fiber wet-spinning production of electrically conductive and highly stretchable PU/PEDOT:PSS fibers is demonstrated for the first time. The PU/PEDOT:PSS fibers possess the mechanical properties appropriate for knitting various textile structures. The knitted textiles exhibit strain sensing properties that were dependent upon the number of PU/PEDOT:PSS fibers used in knitting. The knitted textiles show sensitivity (as measured by the gauge factor) that increases with the number of PU/PEDOT:PSS fibers deployed. A highly stable sensor response was observed when four PU/PEDOT:PSS fibers were co-knitted with a commercial Spandex yarn. The knitted textile sensor can distinguish different magnitudes of applied strain with cyclically repeatable sensor responses at applied strains of up to 160%. When used in conjunction with a commercial wireless transmitter, the knitted textile responded well to the magnitude of bending deformations, demonstrating potential for remote strain sensing applications. The feasibility of an all-polymeric knitted textile wearable strain sensor was demonstrated in a knee sleeve prototype with application in personal training and rehabilitation following injury.

Evolution of 3D printed soft actuators

Developing soft actuators and sensors by means of 3D printing has become an exciting research area. Compared to conventional methods, 3D printing enables rapid prototyping, custom design, and single-step fabrication of actuators and sensors that have complex structure and high resolution. While 3D printed sensors have been widely reviewed in the literature, 3D printed actuators, on the other hand, have not been adequately reviewed thus far. This paper presents a comprehensive review of the existing 3D printed actuators. First, the common processes used in 3D printing of actuators are reviewed. Next, the existing mechanisms used for stimulating the printed actuators are described. In addition, the materials used to print the actuators are compared. Then, the applications of the printed actuators including soft-manipulation of tissues and organs in biomedicine and fragile agricultural products, regenerative design, smart valves, microfluidic systems, electromechanical switches, smart textiles, and minimally invasive surgical instruments are explained. After that, the reviewed 3D printed actuators are discussed in terms of their advantages and disadvantages considering power density, elasticity, strain, stress, operation voltage, weight, size, response time, controllability, and biocompatibility. Finally, the future directions of 3D printed actuators are discussed.

High-performance multifunctional graphene yarns: toward wearable all-carbon energy storage textiles

The successful commercialization of smart wearable garments is hindered by the lack of fully integrated carbon-based energy storage devices into smart wearables. Since electrodes are the active components that determine the performance of energy storage systems, it is important to rationally design and engineer hierarchical architectures atboth the nano- and macroscale that can enjoy all of the necessary requirements for a perfect electrode. Here we demonstrate a large-scale flexible fabrication of highly porous high-performance multifunctional graphene oxide (GO) and rGO fibers and yarns by taking advantage of the intrinsic soft self-assembly behavior of ultralarge graphene oxide liquid crystalline dispersions. The produced yarns, which are the only practical form of these architectures for real-life device applications, were found to be mechanically robust (Young's modulus in excess of 29 GPa) and exhibited high native electrical conductivity (2508 ± 632 S m(-1)) and exceptionally high specific surface area (2605 m(2) g(-1) before reduction and 2210 m(2) g(-1) after reduction). Furthermore, the highly porous nature of these architectures enabled us to translate the superior electrochemical properties of individual graphene sheets into practical everyday use devices with complex geometrical architectures. The as-prepared final architectures exhibited an open network structure with a continuous ion transport network, resulting in unrivaled charge storage capacity (409 F g(-1) at 1 A g(-1)) and rate capability (56 F g(-1) at 100 A g(-1)) while maintaining their strong flexible nature.

Design and fabrication of a capacitance based wearable pressure sensor using e-textiles

This paper addresses the methods used for the design and fabrication of a capacitance based wearable pressure sensor fabricated using neoprene and (SAC) plated Nylon Fabric. The experimental set up for the pressure sensor is comprised of a shielded grid of sensing modules, a 555 timer based transduction circuitry, and an Arduino board measuring the frequency of signal to a corresponding pressure. The fundamental design parameters addressed during the development of the pressure sensor presented in this paper are based on size, simplicity, cost, adaptability, and scalability. The design approach adopted in this paper results in a sensor module that is less obtrusive, has a thinner and flexible profile, and its sensitivity is easily scalable for ‘smart’ product applications across industries associated to sports performance, ergonomics, rehabilitation, etc.

Application of soluble poly (3-alkylpyrrole) polymers on textiles

Soluble conducting poly(3-decanylpyrrole) was directly applied to textiles as a nanoparticle emulsion, using a variety of techniques including hand-brushing, dipping and spray painting. These coatings were compared to those formed by chemical polymerization of 3-decanylpyrrole on the surface of the textile by solution, using vapor and spray polymerization methods. The coating formed using chemical polymerization methods had lower surface resistivity than that formed by direct application of a soluble polymer.

It was observed that applied coatings of poly(3-decanylpyrrole) showed a smoother surface morphology with a more even dispersion compared to those formed by chemical methods.

Polymerising pyrrole on polyester textiles and controlling the conductivity through coating thickness

The surface resistance of polypyrrole (PPy)-coated polyester fabrics was investigated and related to coating thickness, which was controlled by adjusting the reactant concentrations. The thickness of the coating initially increased rapidly followed by a steady increase when the concentration of pyrrole (Py) was larger than a concentration of approximately 0.4 mg/ml. The surface resistance decreased from 10⁶ to 10³ Ω with increase in pyrrole concentration within 0.2 mg/ml until the concentration reached a value of about 0.4 mg/ml, above which the rate of decrease diminished. The effect of initial treatment with monomer or oxidant prior to polymerisation reaction with regards to thickness and surface resistance was minimal. The immersion time of the textile into the monomer solution prior to polymerisation reaction did not have a significant effect on the abrasion resistance.

Dielectric characterization of conducting textiles using free space transmission measurements: accuracy and methods for improvement

The dielectric behaviour of in-situ polymerized thin polypyrrole (PPy) films on synthetic textile substrates were obtained in the 1–18 GHz region using free space transmission and reflection methods. The PPy/para-toluene-2-sulphonic acid (pTSA) coated fabrics exhibited an absorption dominated total shielding effectiveness (SE) of up to −7.34 dB, which corresponds to more than 80% of incident radiation. The permittivity response is significantly influenced by the changes in ambient conditions, sample size and diffraction around the sample. Mathematical diffraction removal, time-gating tools and high gain horns were utilized to improve the permittivity response. A narrow time-gate of 0.15 ns produced accurate response for frequencies above 6.7 GHz and the high gain horns further improved the response in the 7.5–18 GHz range. Errors between calculated and measured values of reflection were most commonly within 2%, indicating good accuracy of the method.

Smart cluster bombs - control of multi-agent systems for military applications

This paper introduces an aggregation algorithm for airborne swarming guided weapon systems, which can aggregate munitions into a given shape while reaching the surface. The algorithm uses an artificial force based controller to navigate the members of the swarm into the desired geographical position and evenly distribute them inside the shape. Inter-member repulsion forces are used to avoid collisions among members, which is crucial for a weapon deployment system. Moreover, a lower bound for the release height was obtained which guarantee convergence of the complete weapon system into the target area. The proposed swarming guided weapon system was tested using computer simulations.

RFID-based real-time smart waste management system

In an environmental context, the use of RFID (radio frequency identification) and load cell sensor technology can be employed for not only bringing down waste management costs, but also to facilitate automating and streamlining waste (e.g., garbage, recycling, and green) identification and weight measurement processes for designing smart waste management systems. In this paper, we outline a RFID and sensor model for designing a system in real-time waste management. An application of the architecture is described in the area of RFID and sensor based automatic waste identity, weight, and stolen bins identification system (WIWSBIS).

A proposed smart-card solution for Australian health services : the problems encountered

This case study describes the experience of a state government health department in evaluating the use of smart card technology to redesign health benefits programs for the disabled in Australia. The social and political context of the system is explained in detail, and the potential benefits and risks accruing to the government, health care intermediaries and the community are examined.