Smart Textiles

Wearable Nanotechnology

Nazire Deniz Yilmaz, Nazire D. Yilmaz

• Publisher: Wiley-Scrivener
• Year: 2018
• ISBN:
  9781119460350
• Edition: 1
• Topic: Tecnología e ingeniería
• Subtopic: Nanotecnología y MEMS

Smart Textiles: Wearable Nanotechnology provides a comprehensive presentation of recent advancements in the area of smart nanotextiles giving specific importance to materials and production processes. Different materials, production routes, performance characteristics, application areas and functionalization mechanisms are covered. The book provides a guideline to students, researchers, academicians and technologists who seek novel solutions in the related area by including groundbreaking advancements in different aspects of the diverse smart nanotextiles fields. This ground-breaking book is expected to spark an inspiration to allow future progress in smart nanotextiles research.

The diversity of the topics, as well as the expert subject-matter contributors from all over the world representing various disciplines, ensure comprehensiveness and a broad understanding of smart nanotextiles.

Section 1
INTRODUCTION

Chapter 1
Introduction to Smart Nanotextiles

Nazire Deniz Yilmaz

Textile Technologist Consultant, Denizli, Turkey

Email: [email protected]

Abstract

This chapter provides a comprehensive presentation of recent advancements in the area of smart nanotextiles giving specific importance to materials and their production processes. Different materials, production routes, performance characteristics, application areas, and functionalization mechanisms are referred to. Not only the mainstream materials, processes, and functionalization mechanisms, but also alternatives that do not enjoy wide state-of-the-art use, but have the potential to bring the smart nanotextile applications one step forward, have been covered. Basics of smart nanotextiles, introduction to smart nanotextile components such as nanofibers, nanosols, responsive polymers, nanowires, nanocomposites, nanogenerators, as well as fundamentals of production procedures have been explained. In addition to materials and production technologies, characterization techniques, which have uppermost importance in ensuring proper functioning of the advanced features of smart nanotextiles, have also been investigated.

Keywords: Smart textiles, nanofibers, nanosols, nanowires, responsive polymers, nanocomposites, nanogenerators, characterization, fiber production, nanocoating

1.1 Introduction

Originally, textiles/clothing relates to catering the needs for protecting the human body from cold, heat, and sun. A more comprehensive definition of conventional textiles also include home textiles utilized in furnishing and the ones that find use in the bedroom and the bathroom [1, 2]. Following these basic needs, aesthetics have become one of the main drivers for people to use clothing and textiles [3]. Recently, more functionality has started to be required, so functional textiles/technical textiles, which can cater more sophisticated needs, have emerged. The last generation of textiles, smart textiles, is capable of one step ahead: sensing and reacting to environmental stimuli [2, 4, 5].

Smart textiles can be also named as “intelligent,” “stimuli-sensitive,” or “environmentally responsive” [6]. Smart textiles have been described as “fibers and filaments, yarns together with woven, knitted or non-woven structures, which can interact with the environment/user” [7, p. 11958]. Smart textiles have broadened the functionality and, consequently, application areas of conventional textiles [7], as they show promise for use in various applications including biomedicine, protection and safety, defense, aerospace, energy storage and harvesting, fashion, sports, recreation, and wireless communication [4, 8–10].

Smart textile components perform various functions such as sensing, data processing, communicating, accumulating energy, and actuating as shown in Figure 1.1 [11]. In these fields, textile structures present some advantages such as conformability to human body at rest and in motion, comfort in close contact to skin, and suitability as substrates for smart components [8].

Figure 1.1. Smart textile components. (Reprinted from reference [11], with permission of Elsevier.)

“Smartness” refers to the ability to sense and react to external stimuli [6]. The stimulus of interest can be electrical, mechanical, chemical, thermal, magnetic, or light [4, 12]. Smart systems offer the capability of sensing and responding to environmental stimuli, preferably in a “reversible” manner, that is, they return to their original state once the stimulus is “off” [6].

Smart textiles can act in many ways for vast purposes including releasing medication in a predetermined way, monitoring health variables, following pregnancy parameters [13], aiding physical rehabilitation [14], regulating body temperature, promoting wound healing [15], facilitating tissue engineering applications [16], photocatalytic stain removing [17], preventing flame formation [18], absorbing microwaves [19], interfering with electromagnetic radiation [20], wireless communicating between persons, between person and device, and between devices (as in the case of IoT), and harvesting and storing energy [10]. In an everyday example, the smart textiles used for fashion, kids’ toys, or entertainment can change color, illuminate, and display images and even animations [4, 10].

Smart textiles have attracted international research interest as reflected in the programs of the international funding bodies, for example, “Wear Sustain,” a project funded by the European Commission. The Wear Sustain Project is directed by seven organizations, both public and private entities, across Europe, including universities, research centers, and short- and middle-scale enterprises (SMEs). This project has launched 2.4 million euros for funding teams to develop prototypes of next-generation smart textiles [21]. US-based National Science Foundation grants $218,000 to a career project titled Internet of Wearable E-Textiles for Telemedicine [22]. NSF of the USA has invested more than $30 million on projects studying smart wearables. The projects include belly bands tracking pregnancy variables, wearables alerting baby sleep apnea, and sutures that collect diagnostic data in real time wirelessly. NSF also supports the Nanosystems Engineering Research Center (NERC) for Advanced Systems for Integrated Sensors and Technologies (ASSIST) at North Carolina State University working on nanotechnological wearable sensors [23].

Different components are used for imparting smartness into textiles. These components include conductive fibers, conductive polymers, conductive inks/dyes, metallic alloys, optical fibers, environment-responsive hydrogels, phase change materials, and shape memory materials. These components are utilized in forming sensors as well as electrical conductors, and connection and data transmission elements [4]. Conductive materials added to fibers/yarns/fabrics include conductive polymers, carbon nanotubes, carbon nanofibers, or metallic nanoparticles [4, 24–26].

“Smartness” can be incorporated into textiles at different production/treatment steps including spinning weaving [27], knitting [28], braiding [29], nonwoven production [30], sewing [31], embroidering [3], coating/laminating [32], and printing [33] as shown in Figure 1.2.

Figure 1.2. Production steps of textiles. (The image has been prepared by the author.)

Conventionally, conductive fibers and yarns are produced through adding conductive materials to fibers, or via incorporation of metallic wires/fibers such as stainless steel or other metal alloys [4, 25]. Another way to produce smart textiles is through incorporation of conductive yarns in fabrics, for example, by weaving. Drawbacks related with this method are the complexity, non-uniformity, as well as difficulty in maintaining comfortable textile properties [7].

Nanotechnology has carried the level of smart textiles one step further. Via application of nanosized components, textile materials receive smart functionalities without deteriorating textile characteristics [10, 34]. Consequently, functions conventionally presented by nonflexible rigid bulk electronic products are achieved by “clothes” [2].

Smart wearables should present capability of recognizing the state of the wearer and/or his/her surrounding. Based on the received stimulus, the smart system processes the input and consequently adjusts its state/functionality or present predetermined properties. Smart textiles should also cater needs regarding wearability [7]. Via incorporation of nanotechnology, the clothing itself becomes the sensor, while maintaining a reasonable cost, durability, fashionability, and comfort [35].

Based on their “smartness” level, smart textiles may be investigated under three categories [33]:

• – Passive smart textiles
• – Active smart textiles
• – Very active smart textiles.

The first group can only detect environmental stimuli (sensor), whereas the second group senses and reacts to environmental stimuli (sensor plus actuator). On the other hand, the third group senses and reacts to environmental stimuli, and additionally adapts themselves based on the circumstances (sensor, actuator, and controlling unit) [2, 4].

1.1.1 Application Areas of Smart Nanotextiles

Potential application areas of smart textiles are innumerable. In terms of personal use, they can act for making us feel comfortable, warn and protect us against dangers, monitor biometric data, treat diseases and injuries, and improve athletic performance via use of sensor-embedded clothing. Furthermore, they can be used by military and other security staff for communication. Fashion and decoration are also irreplaceable applications for clothing, not excluding smart wearables. Related examples include color-changing, lighting-up, picture-video-displaying wearables [4, 33].

As textiles are in close contact with human body over a large surface area, sensors can be placed at different locations, which presents advantage for biomedical applications. This fact provides greater flexibility and closer self- and remote monitoring of health variables. Smart textile components responsive to pressure/strain can be used to measure heart rate, blood pressure, respiration, and other body motions. Accordingly, piezo-resistive fibers can be utilized as pressure/stress sensors [7, 13]. Smart textiles also show promise for sensing body temperature [2], movements of joints [14], blood pressure, cardiac variables [36], respiration [37], presence/concentration of saline, oxygen, and contamination or water. Thermocouples can be utilized in measuring temperature, whereas carbon electrodes are used for detecting concentrations of different biological fluids [38].

As expected, active smart functionality needs energy to act, which in turn necessitates generation or storage of power. Power generation may be attained via use of piezoelectric [5], photovoltaic [39], or triboelectric components [40], which can harvest energy from motion, light, or static electricity, respectively [10].

1.1.2 Incorporating Smartness into Textiles

Smart textile components include conductive polymers, conductive ink, conductive rubber, optical fibers, phase changing materials, thermochromic dyes, shape-memory substances, miniature electrical circuits, and so on. In terms of textil...

Table of contents

• Cover
• Title page
• Copyright page
• Preface
• Acknowledgments
• Section 1: Introduction
• Section 2: Materials for Smart Nanotextiles
• Section 3: Production Technologies for Smart Nanotextiles
• Index
• End User License Agreement