smart fabrics

SEMINAR REPORT 2012

SMART FABRICS

1,INTRODUCTION

Since the nineteenth century, revolutionary changes have been occurring at an unprecedented rate in many fields of science and technology, which have profound impacts on every human being. Inventions of electronic chips,, the Internet, the discovery and complete mapping of the human genome, and many more, have transformed the entire world. The last century also brought tremendous advances in the textile and clothing industry, which has a history of many thousands of years. Solid foundations of scientific understanding have been laid to guide the improved usage and processing technology of natural fibres and the manufacturing of synthetic fibres. We have learnt a lot from nature. Viscose rayon, nylon, polyester and other synthetic fibres were invented initially for the sake of mimicking their natural counterparts. The technology has progressed so that synthetic fibres and their products surpass them in many aspects. Biological routes for synthesizing polymers or textile processing represent an environmentally friendly, sustainable way of utilizing natural resources. Design and processing with the aid of computers, automation with remote centralized or distributed control, and Internet-based integrated supply-chain management systems bring customers closer to the very beginning of the chain than ever before

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.Looking ahead, the future promises even more. What new capacities should we expect as results of future developments? They should at least include terascale, nano scale, complexity, cognition and holism. The new capability of terascale takes us three orders of magnitude beyond the present general-purpose and generally accessible computing capabilities. In a very short time, we will be connecting millions of systems and billions of information appliances to the Internet.

Technologies allowing over one trillion operations per second are on the agenda for research. The technology in nanoscales will take us three orders of magnitude below the size of most of today’s human-made devices. It will allow us to arrange atoms and molecules inexpensively in most of the ways

permitted by

physical laws. It will let us make supercomputers that fit on the head of a fibre, and fleets of medical nanorobots smaller than a human cell to eliminate cancers, infections, clogged arteries and even old age. Molecular manufacturing will make exactly what it is supposed to make, and no pollutants will be produced. We are living in this exciting era and feeling the great impacts of technology on the traditional textiles and clothing industry, which has such a long history.

Traditionally, many fields of science and engineering have been separate and distinct. Recently, there has been considerable movement and convergence between these fields of endeavour and the results have been astonishing. Smart technology for materials and structures is one of these results. What are smart materials and structures? Nature provides many examples of smart structures. The simple singlecelled living creature may highlight the fundamentals. various environmental conditions or stimuli act on the outer layer.

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These conditions or stimuli may be in the form of force, temperature, radiation, chemical reactions, electric and magnetic fields.Sensors in the outer layer detect these ejects, and the resulting information is conveyed for signal processing and interpretation, at which point the cell reacts to these environmental conditions or stimuli in a number of ways, such as movement, changing chemical composition and reproductive actions. Nature has had billions of years and a vast laboratory to develop life, whereas humankind has just begun to create smart materials and structures. Smart materials and structures can be defined as the materials and structures that sense and react to environmental conditions or stimuli, such as those from mechanical, thermal, chemical, electrical, magnetic or other sources. According to the manner of reaction, they can be divided into passive smart, active smart and very smart materials. Passive smart materials can only sense the environmental conditions or stimuli; active smart materials will sense and react to the conditions or stimuli; very smart materials can sense, react and adapt themselves accordingly. An even higher level of intelligence can be achieved from those intelligent materials and structures capable of responding or activated to perform a function in a manual or preprogrammed manner. Three components may be present in such materials: sensors, actuators and controlling units. The sensors provide a nerve system to detect signals, thus in a passive smart material, the existence of sensors is essential. The actuators act upon the detected signal either directly or from a central control unit; together with the sensors, they are the essential element for active smart materials. At even higher levels, like very smart or intelligent materials, another kind of unities essential, which works like the brain, with cognition, reasoning and activating capacities. Such textile materials and structures are becoming possible as the result of a successful marriage of traditional textiles/clothing technology with material science, structural mechanics, sensor and actuator technology, advanced processing technology, communication, artificial in-telligence, biology, etc.

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2,DEFINITION

The term “Smart Fabrics” refers to a broad and somewhat ill-defined field of study and products that extend the functionality and usefulness of fabrics. Humanity has used various types of fabrics for thousands of years to keep warm, provide comfort, and protect from the elements of nature. For most of recorded history, fabrics have also provided a means of self-expression through colors, patterns, cuts, and other stylistic elements. Aside from the vagaries of fashion and variations in practical application, humanity’s use of fabric has not extended far beyond the basic needs of protection, comfort, and expression. Recent times (within the last 100 years) have seen the use of specialized, synthetic fabrics that are suitable for specific applications (e.g. Nomex, for its fire-retardant capabilities, or Kevlar, for its high strength), but these fabrics are still passive elements. There is some disagreement over the scope of Smart Fabrics, but a broad definition would state that Smart Fabric is traditional fabric with integrated active functionality. Active functionality could include power generation or storage, human interface elements, sensing devices, radio frequency (RF) functionality, or assistive technology. The basic technological elements of smart fabric are conductive or semi conductive threads and yarns, nanoelectronics applied directly to fibres, yarns, or woven elements, and chemical treatments that provide different features. Smart Fabrics differ from Wearable Electronics in that wearable devices are merely contained and carried by clothing, where Smart Fabrics have the functionality of wearable devices actually integrated into the fabric. This is an important distinction to make, because several commercial products marketed as “Smart Fabric” are actually “regular” fabric that envelopes traditional electric, electronic, and/or electromechanical (EEE) devices.

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3,DISTINCT TYPES OF SMART FIBRES

There are actually four distinct types of smart fibres -

1.Passive Smart fibres

Where the clothing "reads" or senses the environment or something about the person wearing the clothing. Wearable sensors fall into this category, with examples including built-in GPS, clothing-integrated baby breathing monitors, and clothing that gives feedback about potential changes in weather.

2.Active Smart fibres

Where clothing not only senses the environment, but also reacts to it. Examples include: Clothing that changes density depending on the temperature outside, jackets that store solar energy that can be used to charge cell phones and cameras, and even built-in sensors that can guide pinpoint massage to a wearer that is regulated depending on his or her level of stress.

3. Active very smart fibres

Where clothing has built in computing and or intelligent sensing capacity. Examples include sleeves that function as keyboards for a small handheld device, clothing that can function like a powerful calculator or PDA, and shirts that can store information through a built-in fabric keyboard and send it via Bluetooth to a computer.

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4. Ultra Smart Textiles:

Very smart textiles are the third generation of smart textiles, which can sense, react and adopt themselves to environmental conditions or stimuli. A very smart or intelligent textile essentially consists of a unit, which works like the brain, with cognition, reasoning and activating capacities. The production of very smart textiles is now a reality after a successful marriage of traditional textiles and clothing technology with other branches of science like material science, structural mechanics, sensor and actuator technology, advance processing technology, communication, artificial intelligence, biology, etc New fibre and textile materials, and miniaturised electronic components make the preparation of smart textiles possible, in order to create truly usable smart clothes. These intelligent clothes are worn like ordinary clothing, providing help in various situations according to the designed applications.

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4,NEW/SMART MATERIALS AND FIBRES USED IN SMARTTEXTILES

'Smart' or 'Functional' materials usually form part of a 'Smart System' that has the capability to sense its environment and the effects thereof and, if truly smart, to respond to that external stimulus via an active control mechanism. Smart materials and systems occupy a 'Technology space', which also includes the areas of sensors and actuators.

1.shape memory materials

Principle of shape memory materials There are two types of Shape Memory Materials

The first classes are

materials stable at two or more temperature states. In these different temperature states, they have the potential to assume different shapes, when their transformation temperatures have been reached. This technology has been pioneered by the UK Defence Clothing and Textiles Agency.

Fig 1 Shape Memory Materials

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The other types of shape memory materials are the electro active polymers, which can change shape in response to electrical stimuli. In the last decade there have been significant developments in electro active polymers (EAPs) to produce substantial change in size or shape and force generation for actuation mechanisms in a wide range of applications. In contrast to many conventional actuation systems, many types of EAPs are also capable of providing sensing functions. EAPs can provide a range of basic actuator mechanisms, force and displacement levels.

Shape Memory Materials

Shape memory alloys, such as nickel-titanium, have been developed to provide increased protection against sources of heat. A shape memory alloy possesses different properties below and above the temperature at which it is activated. Below this temperature, the alloy is easily deformed. At the activation temperature, the alloy exerts a force to return to a previously adopted shape and becomes much stiffer. The temperature of activation can be chosen by altering the ratio of nickel to titanium in the alloy . Cuprous-zinc alloys are capable of a two-way activation and therefore can produce the reversible variation needed for protection from changeable weather conditions. They will also react to temperature changes brought about by variations in physical activity levels. Shape Memory Polymers have the same effect as the Ni-Ti alloys but, being polymers, they will potentially be more compatible with textiles. The first SMPs were polynorborene-based with a Tg range of 35ºC to 40ºC developed by French CdF Chimie Company.

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Later, several classes of SMPs based on mix of styrene - butadiene polyethylene Terephtalate - Polyetylene Oxyde - Polyurethane - Polycaprolactone etc, were developed with Tg from -46°C to 125°C for a widening of the types of application Electro active polymers EAPs are generally made up of high functionalised polymer. One of the most famous EAPs is the "Gel robots" made up of poly 2 -acrylamido -2- methylpropane sulfonic acid that is fully researched for applications in the replacement of muscles and tendons

Applications in Smart Textiles

For clothing applications, the desirable temperatures for the shape memory effect to be triggered will be near body temperature. In practice, a shape memory alloy is usually in the shape of a spring. The spring is flat below the activation temperature but becomes extended above it. By incorporating these alloys between the layers of a garment, the gap between the layers can be substantially increased above the activation temperature. Consequently, considerably improved protection against external heat is provided Polyurethane films have been made which can be incorporated between adjacent layers of clothing. When the temperature of the outer layer of clothing has fallen sufficiently, the polyurethane film responds so that the air gap between the layers of clothing becomes broader. This broadening is achieved if, on cooling, the film develops an out-of-plane deformation, which must be strong enough to resist the weight of the clothing and the forces induced by the movements of the wearer. The deformation must be capable of reversal if the outer layer of clothing subsequently becomes warmer

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Some active smart fibres contain electric conductive materials, Phase Change Materials PCM, and graphite particles, which can conduct electricity. In this way the resistance of the fibre is changeable along with the change of the fibre temperature due to change of fibre volume. As the material warms, it expands and reduces conductivity between graphic particles. These materials can automatically regulate the on/off of the electricity and keep the temperature stable.

The shape memory alloys can also contribute to the miniaturisation of equipment and systems, decrease the number of parts required and extend the life expectancy too due to the favourable fatigue properties of the alloy Considerable progress still needs to be made with EAP technologies before commercially viable applications. A multidisciplinary approach is essential for future developments. Applications such as fabrics and textile structures will require fibre-like EAP actuators and sensors in order to achieve effective integration. The large stimulated displacements that have been observed have encouraged new thinking in terms of both applications and designs. The natural ease of preparing and shaping such materials, coupled with their low mass and large displacements, opens up new approaches in many traditional areas as well as the potential to enable new technologies.

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2.chromic materials definition

Other types of intelligent textiles are those, which change their colour reversibly according to external environmental conditions, for this reason they are also called chameleon fibres. Chromic materials are the general term referring to materials which radiate the colour, erase the colour or just change it because its induction caused by the external stimulus, as "Chromic" is a suffix that means colour. Therefore we can classify chromic materials depending on the stimulus affecting them in bold are indicated those used in textile). Photochromic: external stimulus is light Thermochromic: external stimulus is heat Electrochromic: external stimulus is electricity Piezorochromic: external stimulus is pressure. Solvatechromic: external stimulus is liquid or gas.

Materials and applications in Smart Textiles 1.Photocromic materials are generally reversible unstable organic molecules that change of molecular configuration with the influence of a special radiation. The molecular arrangement also perturbs the absorption spectra of the molecule and in consequences it colour. The applications in textile are intended to the fashion area and only a few for the solar protection. A T-shirt made of photochromic prompted fabric was introduced in the market in 1989

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2.Thermochromic materials

are those whose colour changes as a result of reaction to heat, especially through the application of thermochromic dyes whose colours change at particular temperatures. Two types of thermochromic systems that have been used successfully in textiles are: the liquid crystal type and the molecular rearrangement type. In both cases, the dyes are entrapped in microcapsules and applied to garment fabric like a pigment in a resin binder The most important types of liquid crystal for thermochromic systems are the so-called cholesteric types, where adjacent molecules are arranged so that they form helices. Thermochromism results from the selective reflection of light by the liquid crystal. The wavelength of the light reflected is governed by the refractive index of the liquid crystal and by the pitch of the helical arrangement of its molecules. Since the length of the pitch varies with temperature, the wavelength of the reflected light is also altered, and colour changes occur. An alternative means of inducing thermochromism is by means of a rearrangement of the molecular structure of a dye, as a result of a change in temperature The most common types of dye, which exhibit thermochromism through molecular rearrangement, are the spirolactones, although other types have also been identified. A colourless dye precursor and a colour developer are both dissolved in an organic solvent. The solution is then microencapsulated and is solid at lower temperatures. Upon heating, the system becomes coloured or loses colour at the melting point of the mixture. The reverse change occurs at this temperature if the mixture is then cooled. However, although thermochromism through molecular rearrangement in dyes has aroused a degree of commercial interest, the overall mechanism underlying the changes in colour is far from clear-cut and is still very much open to speculation

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Toray Industries reported in 1987 the development of a temperature sensitive fabric by introducing microcapsules, diameter 3 - 4 mm to enclose heat sensitive dyes, which are resin coated homogeneously over fabric surface. The microcapsule was made of glass and contained the dyestuff, the chromophore agent (electron acceptor) and colour- neutraliser (alcohol, etc), which reacted and exhibited colour/decolour according to the environmental temperature. SWAY was multicolour fabric, with basic 4 colours and combined 64 colours. SWAY can reversibly change colour at temperature greater than 5°C and is operable from - 40 to 80°C. The change of colour with temperature of these fabrics is designed to match the application, eg, for skiwear 11 - 19°C, women's clothing 13 22°C and temperature shades 24 - 32°C Other types of SFIT that use this effect are the electrically warming textiles (with Joules effect), which change colour with both the effect of warm and thermochromic materials

Uses of thermochromic inks by the International Fashion Machine

In addition to the changing of colour due to reaction to light or heat there are other chromic fibres presenting others characteristics. These fibres have raised the interest of people because of their surprising and interesting nature. Therefore, there is the problem that this "Boom" will soon come to an end because these fibres are only considered to be a temporary fashion material. In order to establish these fibres in everyday life it is especially necessary to improve their endurance to light and to their accuracy.

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Some of these fibres are those that present the phenomenon called solvate chromism whose colour changes when in contact with a liquid, for example water. These materials are normally used for "Design" swimsuits. Apart from this, the most important application for chromic materials is fashion, to create fantasy designs changing its colour depending on the volume of incident light.

Electrostrictive, Magnetostrictive and Elastorestrictive

These are materials that change in size in response to either an electric or magnetic field. Conversely, they can produce a voltage when stretched. Electrorheostatic (ER) and magneto-rheostatic (MR) materials are fluids, which can experience a dramatic change in their viscosity. These fluids can change from a thick fluid (similar to motor oil) to nearly a solid substance within the span of a millisecond when exposed to a magnetic or electric field; the effect can be completely reversed just as quickly when the field is removed. MR fluids experience a viscosity change when exposed to a magnetic field, while ER fluids experience similar changes in an electric field. The composition of each type of smart fluid varies widely. The most common form of MR fluid consists of tiny iron particles suspended in oil, while ER fluids can be as simple as milk chocolate or cornstarch and oil.

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3.membranes materials

Multi-disciplinary research led to the successful development of the cuttingedge technology of laminating a variety of microporous or hydrophilic membranes. The membranes are constituted of polymers and their structure could be made of one or more layers (until 6 layers) according to the wanted properties. Membranes are deposited on textiles in order to add new properties onto theirs surfaces. The polymers used in the membranes may be of several natures such as biopolymer (generally cellulosic), or synthetic as the ployfluorocarbone or the polyurethanes and theirs derivatives.

Applications

One of the main applications of membranes is in the field of sportswear for the manufacture of breathable and impermeable clothes. Indeed, with a simple system of membrane, fabrics possessing an excellent water exchange are obtained with a good elimination of the sweat at the garment interface (breathability) and the creation of an external barrier with extreme water repellence For example, the best provider of textile membranes is Gore that manufactures unique wafer-thin microporous membrane (Gore tex), which contains over 9 millions pores per square inch. Each pore is 20,000 times smaller than a water droplet, yet some 700 times bigger than a moisture vapour molecule. This gives the fabric the excellent levels of waterproofness and breathability that the brand is famous for. Gore-Tex is a bi-component membrane, meaning that it is made up of two parts

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The main part (that you see) is made from expanded polytetrafluoroethylene (ePTFE for short). This is then combined with an oleophobic (oil hating) layer that protects the membrane from the natural oils that the human body emits, insect repellents, cosmetics etc. The outer face of the Gore-Tex fabric is coated with a hydrophobic DWR (Durable Water Repellency) treatment which encourages surface water to bead up and run off, improving the wet weather performance of the garment and promoting breathability by preventing wetting-out of the outer face. Another successful application of the membranes in intelligent textiles is the Lotus effect. Lotus effect results in an ultrahydrophobic finishing (membranes or coating), which provides repellence of the aqueous products and also of the oleic product. The result is that the garment does not have an affinity with any products so that it cannot be dirtied. Another name of this property is self-cleaning garments. Several commercial products exist which use membrane of polytetrafluoroethylene derivatives that present an analogy with the Lotus effect

The sensory Baby Vest

Fig 2 The sensory Baby Vest

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At the ITV Denkendorf, an interdisciplinary team of researchers has been developing a special vest for babies. The sensory baby vest is equipped with sensors that enable the constant monitoring of vital functions such as heart, lungs, skin and body temperature which can be used in the early detection and monitoring of heart and circulatory illness. It is hoped to use this vest to prevent cot death and other lifethreatening situations in babies. The sensors are attached in a way that they do not pinch or disturb the baby when it is sleeping.

Interactive fabrics In our society communication tools, interactivity and portable devices are one of the largest sources of innovation and represent a tremendous market. The integration of portable electronics devices in textiles appeared as a natural market.

The first innovation was a keyboard made in a single layer of fabric using capacitive sensing, where an array of embroidered or silk-screened electrodes make up the points of contact. A finger's contact with an electrode can be sensed by measuring the increase in the electrode's total capacitance. It is worth noting that this can be done with a single bidirectional digital I/O pin per electrode, and a leakage resistor sewn in highly resistive yarn. Capacitive sensing arrays can also be used to tell how well a piece of clothing fits the wearer, because the signal varies with pressure.

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The keypad shown here has been mass-produced using ordinary embroidery techniques and mildly conductive thread. The result is a keypad that is flexible, durable, and responsive to touch. A printed circuit board supports the components necessary to do capacitive sensing and output key press events such as a serial data stream. The circuit board makes contact with the electrodes at the circular pads only at the bottom of the electrode pattern. In a test application, 50 denim jackets were embroidered in this pattern. Some of these jackets are equipped with miniature MIDI synthesisers controlled by the keypad. The responsiveness of the keyboard to touch and timing were found by several users to be excellent.

Several versions of capacitive or flexible keyboards in textile materials

There are several commercial products that are inspired by this keyboard. The most famous are the KENPO jacket that possesses an integrated MP3 lectors and the I-pods jeans by Levis. There are also many efforts effectuated for the integration of mobile phones in garments. A Swedish R&D team has developed a glove that incorporates a phone.

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4.photovoltaic materials

The photovoltaic effect has been discovered in 1839 by Becquerel. Photovoltaic materials possess the property to generate electric current by means of a light excitation. The mechanisms of electricity generation could be effectuated by two processes. The first way is the separation of charges at a p-n junction in a device. The materials used are semiconductor and are generally based on doped silicon. At the p-n junction, electrons and holes are separated and form an electric current in the bulk of semiconductor. The extraction from the devices of both species by means of appropriated electrodes allows the generation of the electricity. The second way is the inverse process of electroluminescence. The materials used are also semiconductor, but more organic or sensitive to light(molecules, polymers, dendrimers). The reception of an appropriate light allows to compounds to pass in an excited state. At the excited state the electron is in the LUMO and the hole in the HOMO. If the electrodes and the power of separation of charges are adapted, the electron and the hole are separated and allow the formation of the current. Actually, silicon solar cell are widely commercialised and depending the crystalline state of the silicon the energy conversion efficiency could vary between 6% for amorphous to 30% for crystalline. It also exist thin film solar cells that are essentially composed of CadmiumTelluride, Copper Indium Selenide (CIS) or Copper Indium Gallium Selenide (ClGS), the efficiency of this solar cells are between 11-14%, and they are very interesting for their weight and thin film characters for application in textile. Finally, the organic solar cells are also very promising for textile applications, but they possess low efficiency, on an average 5%. For this time the organic solar cells are in development, and numerous chemists work on their molecular compositions and the expectancies for this technology are very high in the near future.

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Application

The main application of solar cells in textile is the electric alimentation of integrated electronic devices, e-textile. The alimentation could be made directly from the solar cell to the devices, but the majority of encountered solutions are using of solar for charging batteries that could deliver energy to the appropriate device; recharging mobile phone,Mp3 player. Nowadays, a new field of investigation consists in the deposition of photovoltaic devices on textile substrates. Recently, a multidisciplinary team of German researchers have presented results of a textile supported CIGS solar cell that obtain efficiency of 83%.

Fig 3 Schematic drawing of a conventional polymer based organic solar cell on ITO-coated glass-based substrate.

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5.Luminescent materials

Definition

The difference between chromic and luminescent materials is that, the first one changes colour, when the second one emits, on subjected to stimulus. There are several types of luminescent effects; •

Optic luminescence: conduction of light.

•

Electroluminescence: external stimulus is electricity.

•

Chemioluminescence: external stimulus is chemical reaction.

•

Triboluminescence: external stimulus is friction.

Materials and applications

There are two types of photo luminescent materials, organic and mineral. The organic photo luminescent are rigid compounds (molecular or polymeric), which possess a good molecular conjugation and relaxation mode to allow for the emission of a photon. There are also mineral photo luminescent materials, such as some rare earth (europium iridium). Photo luminescent materials are generally used in textiles for application in dress for a night club and more interestingly in the marking of labels with UV revelation materials for the detection of imitation goods and the security label. Phosphorescent materials have been applied in inks, which can store light and are used in working clothes for road works/repairs in bad-light situations, or for marking arrows on carpets to guide people during a power failure.

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The obtained effect is generally known as glow in the dark

Optic

luminescence is the typical effect encountered in optical fibres. The use of these kinds of technical fibres is now implanted for manufacturing textiles that emit light. There are also applications with optical fibres at the development stage for the creation of screens. As for photo luminescent materials, electroluminescent materials could be also

organic

(molecular or

polymeric) compounds

or mineral

materials.

Electroluminescent compounds are, for this time, little used in textiles. The most common application electroluminescent yarn (constituted by mineral compounds) in the area of fashion garments and also for high visibility protection equipments. However, the electroluminescent phenomena is now one of the most studied in the area of smart textiles, after the emergence of the organic light emitting diodes, which possess a flexible character and that are envisaged for the manufacture of flexible screens adequate for the wearable computer.

Fig 4. Luminescent sheet

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6.conductive materials

Materials

There are two strategies to create electrical or thermal conductive fabrics and two types of materials are being used; metals and polymers. The same materials could be used for the both conductivity (thermal and electrical), because the two processes are similar and results of an electronic agitation/conduction. The first strategy uses high wicking finishes (ink) with a high metallic content that still retains the comfort required for clothing. With the addition of nickel, copper, silver or carbon coatings of varying thickness, these finishes provide a versatile combination of physical and electrical properties for a variety of demanding applications. The second strategy consists in the direct use of conductive yarns. The yarn could constitute metal such as silver, copper or conductive polymer such as poly thiophene, polyaniline and their derivatives[14]. Although there are many different trade marks commercialising these materials, they all have the same main properties. They arelightweight, durable, flexible and cost competitive and they are able to be crimped and soldered and subjected to textile processing without any problems.

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Applications

Conductive fibres braided into a shield or sock offer superior performance against electromagnetic interference, antistatic and also they present various advantages. These

materials increases thermal conductivity, using metal over

conventional polymers and areused in clothing offers sports apparel with the minimum of thermal insulation. Another type of fibres included in this group is carbon fibre. The structure of these materials offers the capability of reading the location, within a fabric sheet, of a pressure point (such as a finger press). It is possible to incorporate this function into an elastic sheet structure, allowing the sheet to conform to many 3-D shapes, including compound curves, while still accurately measuring an X-V position. Readings can be obtained from smart fabricaccording to force and area. This allows the user to differentiate between separately identified inputs ranging from high-speed impact to gentle stroking. The force/area reading is versatile, as fabrics can be constructed to be more sensitive to either force or area. Through this new technology, a pressure sensitive capability can be incorporated almost invisibly into textiles without significantly increasing their cost or compromising any of their properties There are other applications for conductive materials, such as heated clothes for extreme winter conditions or heated diving suits to resist very cold water. In these cases an electrical energy source is needed in order that the material generates energy due to the Joules Effect. The thermal conduction that allows distribution of heat throughout the entire garment or suit. There are also some applications for conductive garments in the domain of the antenna, due to their capacities to receive electromagnetic waves[16]. Finally, some of the main applications of conductive textile materials, are their uses for the power supply of electronic devices in the garments.

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5,SMART DEVICES CONSISTING OF FOLLOWING PARTS

1.Power Generation & Storage All electronic devices require power, and this is a significant design challenge for Smart Fabrics. Researchers at Stanford University [1] have developed a method for treating paper with carbon-nanotube inks to create batteries and electrodes. Paper’s fibrous structure allows the inks to permeate the material to create a strong, flexible bond – the same technology could be applied to fabric substrates rather than paper, to create a fabric-based energy storage device. Power generation can be achieved through piezoelectric elements that harvest energy from motion or photovoltaic elements.

E.g.:

1.Piezoelectric

these are crystals which acquire a charge when compressed, twisted or distorted. Piezoelectric materials have two unique properties which are interrelated. When a piezoelectric material is deformed, it gives off a small but measurable electrical

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Fig 5 piezoelectric crystal discharge. Alternately, when an electrical current is passed through a piezoelectric material experiences a it significant increase in size (up to a 4% change in volume

Fig 6 An illustration of the Piezoelectric Effect

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2.Thermoelectric Power Generator

Micro machined CMOS-compatible thermoelectric generators have been realized, as shown in Fig. They produce an electrical output power of 1.0 W per cm² under load and achieve an open circuit voltage of 10 volts per cm² for a temperature drop of5 K across the device.

These

values are comparable with expensive thermoelectric generators

made of high-end compound semiconductors. The power delivered is suitable for application in wristwatches. The thermoelectric generators have been implemented directly into the fabric of clothes For coupling to the outside world small copper plates are placed both at the warm and cold ends utilizing the high thermal conductivity of this metal. Excellent thermal contact both to the skin and to the ambient air is achieved.

Fig 7 Micro view of CMOS-compatible thermoelectric generators

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\2.Human Interface Elements

Human interfaces to active systems can be roughly grouped into two categories: input devices and annunciation or display devices. Input devices can include capacitive patches that function as pushbuttons, or shape-sensitive fabrics that can record motion or flexing, pressure, and stretching or compression. Capacitive patches can also be used to sense physioelectric signals, which allow for user input via electro myogram (EMG) or electroencephalogram (EEG).

Annunciation and

display devices may include fabric speakers, electroluminescent yarns, or yarns that are processed to contain arrays of organic light emitting diodes (OLEDs). Fabrics can also include elements that provide electro tactile feedback or simply vibrate.

Fig 8 ski gloves

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3,Sensing Devices Fabric-based sensing has been a large field of research in the biomedical and safety communities. Capacitive swatches can be used for electrocardiogram (ECG), EMG, and EEG sensing; fabrics incorporating thermocouples can be used for sensing temperature; luminescent elements integrated in fabrics could be used for biophotonic sensing; shape-sensitive fabrics can sense movement, and can be combined with EMG sensing to calculate muscle fitness. Carbon electrodes integrated into fabrics can be used to detect specific environmental or biomedical features such as oxygen, salinity, moisture, or contaminants.

4,RF Functionality Fabric-based antennas are a relatively simple application of Smart Fabrics. Simple fabric antennas are merely conductive yarns of specific lengths that can be stitched or woven into non-conducting fabrics; more complex antennas may be woven into specific shapes and utilize conductive fabrics for shielding and directional use. The use of fabric antennas has already been explored at length by many parties; such antennas are available for cellular and satellite phones, and have been integrated into NASA’s Extravehicular Mobility Unit (EMU) EVA suit and the KORONA-M communications system for the Russian Space Agency’s ORLAN-M EVA suit.

5,Assistive Devices Fabric with integrated shape memory alloys could stretch, shrink, and bend on command; making it easier to don or doff clothing, maintain the shape of soft packaging, or encourage correct posture. Resistive elements woven into fabric can provide active heating (this is frequently seen in ski gloves).

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6,TEXTILE GAIN INTELLIGENCE

Advances in textile technology, computer engineering, and materials science are promoting a new breed of functional fabrics. Fashion designers are adding wires, circuits, and optical fibres to traditional textiles, creating garments that glow in the dark or keep the wearer warm. Meanwhile, electronics engineers are sewing conductive threads and sensors into body suits that map users whereabouts and respond to environmental stimuli. Researchers agree that the development of genuinely interactive electronic textiles is technically possible, and that challenges in scaling up the handmade garments will eventually be overcome. Now they must determine how best to use the technology. The term µsmart dresser could soon acquire anew meaning. An unlikely alliance between textile manufacturers, materials scientists, and computer engineers has resulted in some truly clever clothing. From self-illuminating handbag interiors to a gym kit that monitors workout intensity, the prototypes just keep coming. But researchers have

yet to answer the million-dollar question, perhaps critical to

consumer acceptance; will they go in the wash? . Designers have been quick to jump onboard the high-tech fabric bandwagon, adopting electronic display technologies to create colorful, novelty clothing items. For example, the Italian-made fabric Luminas®, which contains colour light emitting diodes (LEDs), has been used to make a glow-in-the dark bridal gown, sparkly cocktail dresses, and costumes for opera singers. Luminex is made by binding LED fibres into the ends of ordinary fabric, which then form the seams of tailor made clothing.

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Fig 9 Optoelectronic fabrics France Telecom has gone one step further, developing a flexible, battery-powered optical fibres screen that can be woven into clothing. Each plastic fibres-optic thread is illuminated by tiny LEDs that are fixed along the edge of the display panel and controlled by a microchip. The threads are set up so that certain portions are lit when the LEDs are switched on, while other sections remain dark. These light and dark patches essentially act as pixels for the display screen. A prototype version integrated into a jacket displayed crude but readable symbols. More sophisticated versions may support slogans, safety notices, or simply a range of different geometric patterns can be switched on and off. The marriage of woven fabric with electronics is finding favour in the world of interior design as well. The novel fabric contains interwoven stainless steel yarns, painted with thermo chromic inks, which are connected to drive electronics. The flexible wall hangings can then be programmed to change color in response to heat from the conducting wire

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7,WEARABLE- INTELLIGENCE

Self-heating hats and glow-in-the-dark sweatshirts might correctly be labelled as µsmart but how about a shirt that µknows whether you are free to take a cell phone call or retrieve information from a 1000 page safety manual displayed on your inside pocket? Such items, termed µintelligent clothing to distinguish them from their lower tech cousins, have proved more difficult to patch unobtrusively into everyday apparel. Indeed, the first prototype wearable computers of the early 1990s required users to strap on a head-mounted visor and carry heavy battery packs in their pockets, leading some to question the appropriateness of the term wearable Batteries are now smaller and lighter, and sensors far less cumbersome. But researchers are going to have to integrate electronic components into the fabric itself, if this technology is going to fulfils its potential. Sewing in electrical networking capability is just the first stage though. Genuinely intelligent clothing would be woven from a selection of threadlike electronic sensors and battery fibers. , as well as flexible, conductive fibres. Garments would then be able to function as standalone computers, providing wearers with information about their environment. For example, a context-aware shirt for the blind might be woven with tiny vibrating motors to provide warnings about approaching objects, while workers in the chemical industry could wear overalls capable of detecting a nearby spillage. The cost of developing and manufacturing such sophisticated fabrics is likely to put them beyond the reach of the fashion industry for the time being. The main applications are going to be medical, military, and industrial. Those are the only places that are going to be able to bear the additional cost of the clothing, at least at the outset. And they are also the kind of places that have some compelling applications where it is difficult to use discrete components strapped onto the body

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8,COMPLEXITY VERSUS DURABILITY

The simulation environment is already being used to model a garment that can sense its own shape. Professional golfers and tennis players could also use the shirt to perfect their swing or serve.

The finished item is likely to be fabricated

from cloth containing piezoelectric film fibres that produce a voltage in response to a force and vice versa. ³The film strips allow us to detect movement of the limbs so that we can find their position. Team members are also working to create a wearable version of a giant textile sensor net designed to detect noise. The fabric, developed with support from the US military, is fitted with an acoustic beam former capable of picking up and pinpointing the location ofan approaching vehicle. Electrical connections are made by weaving wires into the heavy-duty cloth, and discrete microphones are

attached

at

suitable

points

though

these

could also be replaced by

piezoelectric film sensors in the future. The researchers are using standard metal snap fasteners (press studs) to make electrical connections between µe-buttons and conductive fibres. The ebuttons, essentially small PC boards, contain the garments core electronics. One part of the fastener is attached to the button, and the other to the item of clothing (Fig. 4). Buttons can then be fixed on when required, swapped with different e-buttons if alternative functionality is required or removed entirely when the garment is washed.

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9,POTENTIAL IMPACT

There is a keen interest in Smart Fabric technology in the medical, sport, fashion, and artistic communities, but Smart Fabric technology presents several challenges. Creating successful smart fabric products requires expertise in many disciplines – textiles, semiconductor physics, nanotechnology, chemistry, physiology, analog and digital electronics, wireless communication, human interfaces, signal processing, ergonomics, and others. According to Smart Garment People, a Danish consulting company, some manufacturers are very experienced with electronics and others with textiles, but few do both well. Research in flexible electronics that could be applied to the Smart Fabrics field has generally occurred in academic environments, with little to no coordination with commercial entities creating Smart Fabric products. Researchs could have wide-ranging benefits for the industry. Most obviously, NASA-sponsored research would lend credibility to a nascent industry whose most visible products so far have been somewhat impractical. The strict requirements for safety, reliability, and low resource utilization would be directly applicable to successful commercial products, so any advances made here would benefit the entire industry. Smart Fabric technology has the potential to radically change the mobile computing industry – imagine pants that are also batteries to power various mobile devices; hats with cellular antenna boosters; shirt sleeves with data storage; gloves that contain controls for your cellular phone, so they can stay on when it’s cold. Other industries would benefit as well: restaurant tablecloths that display menus, daily specials, and allow patrons to page their waiter or waitress; hospital bed sheets that monitor patients; medical monitors that are impossible to forget because they are part of your clothing.

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10,EXAMPLE FOR SMARTFABRICS

1.Wearable antennas

In this program for the US Army, Foster-Miller integrated data and communications antennas into

a soldier

uniform,

maintaining

full

antenna

performance, together with the same ergonomic functionality and weight of an existing uniform. We determined that a loop-type antenna would be the best choice for clothing integration without interfering in or losing function during operations, and then chose suitable body placement for antennas.

Fig 10 Army cloth with integrated communication antenna

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With Foster-Miller's extensive experience in electro-textile fabrication, we built embedded antenna prototypes and evaluated loop antenna designs. The program established feasibility of the concept and revealed specific loop antenna design tradeoffs necessary for field implementation. This program

aimed at

developing soldier ensemble of the future, which will monitor individual health, transmit and receive mission-critical information, protect against numerous weapons, all while being robust and comfortable

2.Georgitech wearable motherboard

Fig 11 smarts -shirt Georgi Tech developed a "Wearable Motherboard" (GTWM which was initially-itended for use in combat conditions. The Sensate Liner for Combat Casualty Care uses optical fibres to detect bullet wounds and special sensors that interconnects in order to monitor vital signs during combat conditions.

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Medical sensing devices that are attached to the body plug into the computerised shirt creating a flexible motherboard. The GTWM is woven so that plastic optical fibers. and other special threads are integrated into structure of the fabric. There are no discontinuities in the GTWM. The GTWM is one piece of fabric, without seams. Because the sensors are detachable from the GTWM, they can be placed at any location, and is therefore adjustable for different bodies. Furthermore, the types of sensors used can be varied depending on the wearer's needs. Therefore, it can be customized for each user. For example, a firefighter could have a sensor that monitors oxygen or hazardous gas levels. Other sensors monitor respiration rate and body temperature or can collect voice data through a microphone. GTWM identifies the exact location of the physical problem or injury and transmits the information in seconds. This helps to determine who needs immediate attention within the first hour of combat, which is often the most critical during battle

The Value Added by GTWM

The GTWM

is a breakthrough technology because

it

is the

first

unobtrusive and non-invasive way of monitoring vital statistics. Furthermore, the GTWM is worn comfortably underneath clothing, like an undershirt, and can be sized to fit a variety of people. Therefore, it is flexible and customizable to the wearer. Another interesting feature of the GTWM is that it is washable

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Fig.12 closer look to smart shirt

The GTWM could be classified as a wearable computing device. Once the wearer has plugged the sensors into the GTWM, he or she proceeds as if wearing any other item of clothing. It is intended to be as unobtrusive as possible, and no direct manipulation of the device is required once the initial setup is completed It is unlike other wearable computers in that it is nearly invisible since it is worn underneath normal clothing

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Availability and Success of GTWM

The GTWM is currently being manufactured for commercial use under the name "Smart Shirt". Sensatex/Lifelink is manufacturing the "Smart Shirt", which should be available early next year. The company plans to develop relationships

Fig 13 commercial applications for the "Smart Shirt with fire-fighter groups, doctors and others in order to create "wearable motherboards," that meet their different needs The commercial applications for the "Smart Shirt" are: in figure

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Scenarios of Use for the Smart shirt

Medical Monitoring Disease Monitoring Infant Monitoring Obstetrics Monitoring Clinical Trials Monitoring Athletics Biofeedback

Limitations and Issues of the Smart Shirt

Some of the wireless technology needed to support the monitoring capabilities of the "Smart Shirt" is not completely reliable. The “Smart Shirt" system uses Bluetooth and WLAN. Both of these technologies are in their formative stages and it will take some time before they become dependable and widespread.

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Smart Shirt" Platform Implementation

Fig 14 Smart Shirt" Platform Implementation Additionally, the technology seems to hold the greatest promise for medical monitoring. However, the "Smart Shirt" at this stage of development only detects and alerts medical professionals of irregularities in patients' vital statistics or emergency situations. It does not

yet respond to dangerous health

conditions. Therefore, it will not be helpful to patients if they do face complications after surgery and they are far away from medical care, since the technology cannot yet fix or address these problems independently, without the presence of a physician. Future research in this area of responsiveness is ongoing.

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As is the case for any monitoring system, the privacy of the wearer could be compromised. For example, a GTWM that is outfitted with a microphone or GPS may compromise the wearer's privacy. Additionally, the data that is transferred by the "Smart Shirt" could be used for purposes other than the intended, and could be viewed by unauthorized people. Databases about individuals could also be linked to provide more information than is necessary for this application. All of these possibilities could compromise the privacy of the individual.

In the case of telemedicine and the aforementioned scenario of use with patients recovering from surgery, there is also the possibility that patients may be

released

from

hospitals prematurely because doctors may depend on this

technology to monitor them

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11.FABRIC COMPUTING INTERFACES & FABRIC COMPUTING DEVICES

Designing with unusual materials can create new user attitudes towards computing devices. Fabric has many physical properties that make it an unexpected physical, interface for technology. It feels soft to the touch, and is made to be worn against the body in the most intimate of ways.

Materially, it is both strong and flexible, allowing it to create malleable and durable sensing devices. Constructing computers and computational devices from fabric also suggests new forms for existing computer peripherals, like keyboards, and new types of computing devices, like jackets and hats.

EXAMPLES: 1.Two Fabric Keypads Our fabric keypads offer far greater physical flexibility and softness than existing flexible keyboards. Unlike fabric sensing of the past, these keyboards offer the precision and repeatability necessary to create reliable sensing devices. These keypads can be used to interface with Fig. 2 Quilted Fabric Keypad, Flat, Folded and Rolled everything from a desktop computer, to a pager and an interactive dress.

Fig 15 quilted fabric key pad

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2.Firefly Dress and Necklace The Firefly dress and necklace uses conductive fabric to distribute power throughout the dress. As the wearer moves, LED¶s (small lights) to which we attached fuzzy conductive p ads (the electrical contacts), brush lightly against the fabric power and ground layers, creating a dynamic lighting effect. The necklace, (having no power supply of its own), creates dynamic light effects when its conducting beads and tassels brush against the surface of the dress. These ³opportunistic´ connections allow power to be distributed without hard and fast connectors and wires. The dresses designs reminiscent of the 1920 s and suggests a level of detail and romance rarely associated with technology

3.musical jacket The Musical Jacket incorporates an embroidered fabric keypad, a sewn conducting fabric bus, a battery pack, apair of commercial speakers and a miniature MIDI synthesizer. When the fabric keypad is touched, it communicates through the fabric bus to the MIDI synthesizer, which generates notes. The synthesizer sends audio to the speakers over the fabric bus as well. Power from the batteries is also distributed over the fabric bus. The embroidered keypad and fabric bus allow the elimination of most of the wires, connectors and plastic insets that would make the jacket stiff, heavy and uncomfortable.

Fig 16 musical jacket

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12.CONCLUSION

What smart fabrics cannot is not as important as what it can. This intelligent textiles have managed to pervade into those places where you least expect to find them. It will get hold of your rhythm like a lover. It will enlighten your ways like a mentor. It will care for you like a mother. It will be cautious like a friend. The smart-wears will definitely make you feel in good company, how alone you maybe. One day we may correct Seneca of his saying ³As often I have been with men, I have come back less a man´, and suggest that ³As often I have been in a smart-wear, I have come back wiser a man´.

One day will our senses become superfluous?

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13,BIBLIOGRAPHY

1. Textiles gain intelligence´, Paula Gould, Materials Today, October 2003 2. ³Smart fabric or µWearable computing¶´ , E Rehmi Post, Margaret Roth, MIT Media Laboratory 3. ³E-textiles, the ultimate in Flexible computing´, Virginia Tech Bradley Department of Electrical & Computer Engineering, Annual report 2003. 4. ³Interactive electronic textile development ³ a review by Dina Meoli and Trci May 5. Plumlee, North Carolina State University.Wearable computing lab´, ETH Zurich 6. http://www.sensatex.com 7. http://www.abcnews.go.com/sections/living/DailyNews/bodysensor000919.ht ml 8. http://www.tdctrade.com/imn/imn177/gallery.htm 9. http://www.wearcam.org/personaltechnologies/index.html 10. http://www.philipsdesign.com 11. http://www.softswitch.com 12. http://www.sensatex.com 13. http://www.avantex.com

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