E-TEXTILE – THE NEW INVENTION OF TEXTILE Abstract: This paper provides the latest insights into emerging technology to enhance wear ability of e-textiles and smart clothing by reviewing the cutting-edge researches and development. It will contain the construction process of an e-textile and some relevant application fields. Introduction: It is hard to believe that a fabric we are wearing can monitor our health, guard us in case of any danger, measure the chemical mixture of our body fluids and do many more such things. But of course it is possible in today’s world of technology.
Here we are taking about none other than the electronic textile, which is the commendable invention in the category of smart textile. E textile is used in numerous industries and purposes that are useful not only for human beings but for the entire living beings on the Earth. Electronic textiles or more often called e textiles are the textiles that have electronics and interconnections. These electronics are woven into the fabric to make e textile wearable. With advancement in this sector you can get from very simple computing devices to large and complex sensing and protective textiles.
Definition of E-textile: Although electro-textiles attract a great deal of interest in relevant industries and academia, they do not have any official definition. Electro-textiles, known as e-textiles, refer to fabrics that can electrically function as electronics and physically behave as textiles. The prominent application of e-textiles is smart clothing. Generally, “smart clothing system” refers to a new garment feature that can provide interactive reactions by sensing signals, processing information and actuating the responses.
A group of E-textile research group has given a definition of e-textile like this: “Electronic textiles (e-textiles) are fabrics that have electronics and interconnections woven into them, with physical flexibility and size that cannot be achieved with existing electronic manufacturing techniques. Components and interconnections are intrinsic to the fabric and thus are less visible and not susceptible to becoming tangled together or snagged by the surroundings. An e-textile can be worn in everyday situations where currently available wearable computers would hinder the user.
E-textiles can also more easily adapt to changes in the computational and sensing requirements of an application, a useful feature for power management and context awareness. ” Types of E-textile: E-textile is basically divided into two types. These are: 1. Prototype E-textile. 2. Wireless E-textile. As wireless E-textile is more complicated and is under a lot of research and development, mainly the prototype E-textile will be discussed here. Construction process of an E-textile (Prototype): The most feasible way to wear complicated electronics or computers at this point is to use attachable electronic components.
The clothing itself carries only transmission lines and connectors so that clothing can be flexible and washable enough to be wearable. The attachable electronic system consists of textile transmission lines and connectors. Structures and technologies for textile transmission lines, interconnection methods, and connectors would be explored from a textile perspective. [pic] Figure 1: Concept of Attachable Electronics The textile that needs to be made as an E-textile or Electronic-textile, have to pass through three different stages. These are: 1.
Textile Transmission Line. 2. Interconnection. 3. Connectors. 1. Textile Transmission Line: A textile transmission line consists of conductive yarns integrated into a flexible textile base. In order to produce a successful textile transmission line, the best mix of conductive — metal — and non-conductive — textile — components is critical. The structures of conductive yarn could be categorized into three classes: • Metal-wrapped yarn is a composite of metal and yarn. A conductive yarn mainly consists of a strand of non-conductive yarn wrapped with one or more metal wires (See Figure 2a). For metal-filled yarns, a fine metal wire serves as a core covered by non-conductive fibers (See Figure 2b). Textile coverings can protect a core metal wire, helping it withstand physical stresses and providing electrical insulation. • Metal yarn does not take a core-sheath structure. Metal fibers that are very finely drawn replace one strand or entire strands of the yarn (See Figure 2c). Metal fibers are prepared in forms of either filaments or staple fibers and processed as a conventional yarn.
One or more strands of these conductive yarns are integrated into the fabric substrate to form a textile transmission line. Successful integration creates reliable conductive traces on the fabric while protecting the traces against repeated dimensional changes or abrasions in order to maintain long-term conductivity. Integration methods found in the literature are divided into five groups: woven; knitted; sewn; couched, or e-broidery; and printed structures. The simplest way to embed conductive yarn in fabric is to weave it as one of the warp or weft yarns.
Empirically, plain weave has been preferred because its construction represents the most elementary and simple textile structure, in which no lateral yarn movement is possible and a very stable fabric structure is created. Consisting of interconnected loops, knitted structure is known for its stretchability. No other textile materials can be incorporated except the conductive yarn itself because only one continuous yarn is interlaced. Knitting requires more flexible yarns than do any other structures because the yarn is highly curved to form a loop.
A conductive yarn can be stitched on the fabric surface to create a conductive trace. A sewn trace forms a similar structure to the plain fabric woven with conductive yarns. It is beneficial that a sewing line can cross over seams in apparel composition. Embroidery was previously understood as being just for decorative purposes, but it opens much potential for smart textiles. Conductive threads can be either embroidered or couched by traditional embroidery threads. Embroidery using conductive threads is referred to as electronic embroidery or e-broidery. The fabric becomes more or less rigid and offers poor flexibility. pic] Figure 2: Structures of Conductive Yarns Conductive material is shown in red. 2. Interconnection: Electrical interconnection is required when a conductive path reaches to connectors. The contact area at a junction point is critical for making a good connection. Electrical connections are made possible by soldering or welding, stapling, and bonding. Soldering or welding is a process for joining two or more metals together by melting and cooling them at the junction point (Figure a). Soldering is distinguished from welding in that the base metal is not melted, but solder is melted and filled into the joint.
Hardened solder provides a bending point at which the wire can break after repetitive bending. Stapling is highly recommended in terms of increasing flexibility at the junction points (Figure b). Increased dimensional rigidity may restrict the freedom of motion, which can accelerate fabric tearing. With the possibility of the stitches coming loose, the stability of the connection can be uncertain. Interconnection can be made by using conductive adhesives (Figure c). Conductive adhesives can be envisioned that are nontoxic, highly conductive, highly durable, and moderately flexible. pic] Figure 3: Examples of Interconnection Connectors between electronics and e-textiles need to be specially designed. The fastening should be strong enough to hold the electronics and, at the same time, it should allow them to be easily detached. Traditional forms of apparel fasteners can provide a good connection. For a higher-profile connector, the textile USB cable was developed (See Figure 4). The socket has a rigid pre-mold for durability covered with a soft over-mold for comfort. The mold system will protect the interconnection. [pic] Figure 4: USB Connector
Application of E-textile: There are a lot of sectors where E-textile has been applied successfully. This is mainly done because of the necessity and also to make the current life more comfortable. Sometimes it worked as a matter of fashion and style as well. But beside these, it is being accepted as one of the most important and useful invention of the textile arena. Here are some relevant sectors where E-textile is being used: Protection E-Textiles: Micronanostructured Fibre Systems for Emergency-Disaster Wear The Integrated Project Pro-e-TEX started off in February 2006.
It concentrates on the development of e-textiles to be used in wearable textile systems for emergency disaster intervention personnel and injured civilians. The international consortium joining forces in this project consists of 23 partners from 8 different countries resulting in a representation of the most important European textile regions i. e. Italy, France, Poland and Belgium. The aim of the project is to develop textile-based systems which increase the safety and efficiency of personnel intervening at disasters such as fires, earthquakes, floods and terrorist attacks.
Unfortunately real world incidents have attracted our attention to the necessity to build infallible communication and protection systems. The emergency services which arrive at the disaster site in the first hours need to receive maximum protection. In the last decades the quality of the emergency disaster wear has improved considerably due to the application of e. g. high performance fibres. In a next level protective clothing should be considered from a more systemic point of view with components such as sensors, actuators, signal processing unit, energy supplies and communication systems integrated in the suit.
This leads to a multifunctional suit which offers the following advantages: ?? continuous monitoring of body signals e. g. respiration and heart rate; ?? activity monitoring; ?? internal and external temperature monitoring; ?? wireless communication; ?? chemical detection; ?? energy supply. Not all of these functions can be realized in one garment. For monitoring the vital signals, close contact with the skin is required, while other sensors need to collect data from the wearer’s environment. For this reason the suit will consist of 2 parts: an inner and an outer garment. Also the shoes are part of the system.
For the victims a patch is developed which can closely monitor the wearer’s health condition. A wearable communication system is provided to transfer the collected data. The technological developments necessary to realize this garment emphasize on the development of e-textiles in the shape of fibres, although conventional microsystems will also be considered to reach the anticipated goal. [pic] [pic] Photo: Inner and outer garment and shoes PROETEX prototype Textile-based Sensors with Piezoelectric Properties Piezoelectric materials are materials which generate a voltage in response to an applied mechanical stress.
The piezoelectric effect is reversible in that piezoelectric crystals, when subjected to an externally applied voltage, can change shape by a small amount. Besides the common piezoelectric materials, like crystals or certain ceramic materials, also some polymers exhibit piezoelectric properties. The most well-known piezoelectric polymers are PVDF and its copolymers. A disadvantage of these polymers is that their piezoelectric constant is lower than the one for ceramic materials. Polymers have, however, a lot of advantages, for example processing flexibility, high oltage sensitivity (excellent sensor characteristics), high strength. Multifunctional Medical Textiles for Wound Prevention and Improved Wound Healing: Since September 2006 the European project Lid wine is running, specialized in developing multifunctional medical textiles for decubitus (bed sore) wound prevention and improved wound healing. With 19 partners from nine European countries as well as Israel, the Lid wine consortium constitutes a multidisciplinary team covering the full textile supply chain as well as sectors like medicine, material science and electronics.
The challenge of this project is to establish systems that prevent wounds from occurring at decubitus-risked skin areas and in addition to create optimum wound healing circumstances. In order to achieve this goal different pathways will be followed. Thus, textile systems including an antibacterial textile for wound care with integrated medication depots that release the medication in a controlled way and an active circulation support bandage with reduced friction properties will be developed. The Department of Textiles is actively involved in the development of the latter system, an active circulation support bandage.
In this scope, textiles with integrated electrodes that send electro pulses through the injured body tissues will be produced and as a consequence the blood circulation will be stimulated. As commonly used electrodes can lead to burning injuries of the skin due to a high voltage drop over the skin and an inhomogeneous current density profile, it is imperative to design electrodes with an optimal current distribution. In order to predict the current flow in woven textile electrodes a simulation tool has been developed at the Department of Electronics and Information Systems (ELIS) of Ghent University. pic] [pic] Figure: Enlarged fragment f a woven textile (left) and the equivalent electrical model (right) [pic] [pic] Figure: Current distribution in a woven fabric depending on the correct angle between yarn and the current supply electrodes The current distribution in a woven fabric is depending on various factors, such as the contact resistance between two interlacing fibres, the resistivity of the yarn, and the size of the textile as ell as the contact angle between the yarn and the current supply electrodes, as illustrated in figures above.
By varying those aforementioned parameters it is possible to construct the optimal textile electrode for electro stimulation. The planning foresees to extend this simulation tool for knitted structures and to produce textile electrodes accordingly. Textiles for Monitoring Body Parameters and for Electro stimulation: Textiles are increasingly studied to use them as sensing devices of body parameters, as well as electrodes for therapeutic treatments, such as electro stimulation.
For this purpose they need to be modified to provide reliable electro conductive properties. This can be achieved by depositing lector conductive materials such as metals on the textile surface. Copper and gold are good arterials to use because of their outstanding electro conductive properties and possibility to coat hem chemically and/or electrochemically on the surface of a fibre, yarn or fabric. [pic] Figure: A sportswear which can monitor the body condition Conclusion:
Over the past decade, electronics have been shrinking in size and increasing in functionality. Standardization is the biggest challenge for the industry as it commercializes the wearable systems. It is especially critical for compatibility and connection problems. Standardization should be done in a way that covers the multidisciplinary characteristics of an e-textile as a textile, as an electronic, and as a computer. Another challenge is to ensure personal safety against potential offenses from the wearable system itself or from abusive users.
For example, concerns regarding harmful effects of the electromagnetic field or leaks of confidential information must be cleared before the clothing reaches the users. Current advances in new materials, textile technologies, and miniaturized electronics make wearable systems more feasible. It has been anticipated that batteries or memory storages could be woven directly into textiles. In the future, it might be possible that people can enjoy the freedom not to carry any electronic device, but, instead, to wear it.