Sunday, December 30, 2007

Intelligent Textiles in Medical

The fashion industry is facing new challenges: “intelligent textiles”, “smart clothes”,“i-wear” and “fashion engineering” are only a few of the keywords which will revolutionize new and old industry within the next 5 to 10 years. The integration of high-technology into textiles, e.g. modern communication or monitoring systems or the development of new materials with new functions, has just started with timidity, but the branch already propagates an enormous boom for this sector. Especially applications for the health sector, e.g. clothes with extern monitoring systems, are already today anticipating a great demand . Developments in telecommunication, information technology and computers are the main technical tools for Telemedicine (Telecare, Telehealth, e-health) now being introduced in health care. Telemedicine - medicine at a distance - provides among the many possibilities offered the tools for doctors to more easily consult each other. For individuals, e.g. with chronic diseases, “Telemedicine” means, the possibility to stay in contact with their health care provider for medical advice or even to be alerted if something begins to go wrong with their health. This opens up new possibilities for personalized health and health care. In line with this, ongoing cutting edge research in fields such as textiles, medical sensors and mobile communication could pave the way to a better life for a large number of patients. The results of the researches will indeed make a positive impact on the quality of life for individuals in the real world.
In this review, recent developments on smart garments, designed for medical usage owing to their electronic functions are introduced. The products that appear in the market and application areas are also reviewed.

Medical Aspects of Smart Clothes
"Intelligent Clothing" is made from fabrics that are wireless and washable that integrate computing fibers and materials into the structure of the fabrics. This technology represents a quantum leap in healthcare monitoring, producing accurate, real-time result. A garment can have some functions like a computer by using optical and conductive fibers,

When incorporated into the design of clothing, the technology could quietly monitor the wearer's heart rate, respiration, temperature, and a host of vital functions, alerting the wearer or physician if there is a problem. Judging from the number of inquiries that have been received from parents, physicians and caregivers from all over the world, there is a critical need for the medical smart clothing and this need will be met in the near future.

Smart-Shirt
Georgia Institute of Technology is a university, which conducts research in the area of "intelligent fabric". Georgia Tech developed a "Wearable Motherboard" (GTWM), which was initially intended for use in combat conditions. GTWM is shown on Figure 2. Figure 2. Georgia Tech Wearable Motherboard GTWM is currently being manufactured for commercial use under the name "Smart Shirt" by Sensatex.
The commercial applications for the "Smart Shirt" are as follows:
• Medical Monitoring Disease Monitoring Clinical Trials Monitoring
• Obstetrics Monitoring Infant Monitor Biofeedback
• Athletics Military Uses
The SmartShirt System incorporates advances in textile engineering, wearable computing, and wireless data transfer to permit the convenient collection, transmission, and analysis of personal health and lifestyle data. Described as "the shirt that thinks," the SmartShirt allows the comfortable measuring and/or monitoring of individual biometric data, such as heart rate, respiration rate, body temperature, caloric burn, and provides readouts via a wristwatch, PDA, or voice. Biometric information is wirelessly transmitted to a personal computer and ultimately, the Internet. The "Smart Shirt," a T-shirt wired with optical and conductive fibers, is a garment that functions like a
computer. It uses electro-optical fibers embedded in the fabric to collect biomedical information. There are no discontinuities in the smart shirt. The smart shirt is one piece of fabric, without seams. Because the sensors are detachable from the smart shirt, 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. The information is sent to a transmitter at the base of the shirt where it is stored on a memory chip or sent to your doctor, coach, or personal server via a wireless network like Bluetooth, RF(Radio Frequency), WLAN (Wireless Local Area Network), or cellular.
It uses plastic optical fiber and various sensors and interconnects continuing monitoring human body to detect any dangerous signals or other vital symptoms. A flexible data bus brings the data from sensors to emitters and then sends to PSM (Personal Status Monitor). It is lightweight, comfortable and able to launder. Detailed architecture of the Smart Shirt is shown on Figure 3 and Figure 4.

The system has shown great promise in effectively monitoring the vital signs of infants, as well as chronically ill patients, obstetric patients and the elderly. Similarly the sensor technologies in the garment can be adapted to meet the specific needs of the athletes, astronauts, police officers and firefighters and those involved in hazardous activities [6], [3].
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. 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 Application areas of “Smart Shirt” are as follows:
• Maintaining a Healthy Lifestyle
• Individual Athletes/Team Sports
• Continuous Home Monitoring
• Remote Patient Examination
• Infant Vital Signs Monitoring
• Sleep Studies Monitoring
• Vital Signs Monitoring for Mentally Ill Patients
• Protecting Public Safety Officers
• Battlefield Combat Care Solution
Life-Shirt
Developed by Southern California-based health information and monitoring company VivoMetrics, the Life- Shirt, which is shown on Figure 5, uses embedded sensors and a PDA to monitor and record more than 30 physiological signs and bring standard monitoring technology out of the hospital and into the real-world environment. The information is uploaded to a computer via a datacard and sent over the Internet to VivoMetrics, where it is analyzed and then sent to the physician [8].
The Life-Shirt System is with 12 patents covering wearable sensor design and proprietary software algorithms. It is an enhanced, ambulatory version of an in-patient system currently used in more than 1,000 hospitals worldwide. Underlying Technology The Life-Shirt System is based on inductive plethysmography, a non-invasive respiratory monitoring technology recently cited by the FDA (US Food and Drug Administration) as the only technology capable of differentiating between different kinds of sleep apnea. It monitors breathing patterns by passing a continuous, low-voltage electrical current through externally placed sinusoidal arrays of wires that surround the rib cage and abdomen. By virtue of its design, inductive plethysmography reduces the signal interference and distortion that is often associated with other technologies, enabling clinicians to obtain a more accurate measurement of patients' respiratory functions [8].
Life-Shirt System Components
The Life-Shirt system consists of the Life-Shirt Garment, Life-Shirt Recorder and VivoLogic™ analysis and reporting software. The system continuously measures more than 30 parameters during daily activities. After processing the data, the system integrates subjective patient input from an on-board electronic diary, the VivoLog™ Digital Diary. Results can be viewed as full-disclosure, high-resolution waveforms or as summary reports [8].
Life-Shirt Garment
The Life-Shirt is a lightweight, machine washable, comfortable, easy-to-use shirt with embedded sensors. To measure respiratory function, sensors are woven into the shirt around the patient's chest and abdomen. A single channel ECG measures heart rate, and a two-axis accelerometer records patient posture and activity level. Optional peripheral devices measure blood pressure and blood oxygen saturation. Life-Shirt Recorder and VivoLog™ Digital Diary
The Life-Shirt System includes an integrated PDA that continuously encrypts and stores the patient's physiologic data on a compact flash memory card. Patients may also record time-stamped symptom, mood and activity information in the recorder's diary, the VivoLog™ Digital Diary, allowing researchers and clinicians to correlate subjective patient input with objectively measured physiologic parameters [8].
VivoLogic Software
VivoMetrics proprietary PC-based software decrypts and processes recorded data using patented algorithms. It includes viewing and reporting features that enable researchers and clinicians to view the fulldisclosure, high-resolution waveforms, or look at trends over time. In addition, summary reports can be generated that present processed data in concise, easy-to-interpret graphical and numeric formats. Athletes could wear the garments to enhance training and also can monitor heart rate, respiration, and temperature and even listen to MP3s through the shirt. A microphone also can be embedded into the shirt. Firefighters also could wear a Life-Shirt, which is shown on Figure 6, to be monitored for smoke inhalation. On the other hand doctors could use them to monitor patients who've left their offices.
While this wearable technology is developing and trying to take place in the daily market, the Indy racing league has started to use it in the field to see how a race car driver's body reacts to pressure behind the wheel.

Mamagoose Baby Pyjamas
Smart clothes technologies could help to prevent Sudden Infant Death Syndrome (SIDS) commonly known ‘cot death’. The Belgian company Verhaerth Design and Development and the University of Brussels (VUB) have developed a new type of pyjamas which is shown on Figure 7 that monitor babies during the sleep. The new pyjamas are very aptly called “Mamagoose” and they draw on technology used in two specific applications: The analogue biomechanics recorder experiment and the respiratory inductive plethysmograhph suit. The Mamagoose pyjamas have five special sensors positioned over the chest and stomach, three to monitor the infant’s heart beat and two to monitor respiration. This double sensor system guarantees a high level of
measuring precision. The special sensors are actually built into the cloth and have no direct contact with the body, thus creating no discomfort for the baby. The pyjamas are made of two parts: the first, which comes into direct contact with the baby, can be machine-washed and the second, which contains the sensor system, can be washed by hand. The pyjamas come in three sizes, are made of non-allergic material and have been especially designed to keep the sensors in place during in use. The control unit with alarm system is connected to the pyjamas and continuously monitors and processes the signals received from five sensors. It is programmed with an alarm algorithm which scans the respiration pattern to detect unexpected and possibly dangerous situations. Mamagoose prototypes have been tested on many babies in different hospitals, environments and conditions. These include babies of various weights and sizes when they are different ‘moods’ such as calm, nervous or upset, and when they are sleeping in different positions. To date, the results have been extremely promising [9].

Smart Socks
Every year, more than 50,000 Americans with diabetes must undergo foot or leg amputations. In many of these cases, poor blood circulation is the villain. It’s possible to imagine having socks with built-in pressure sensors that would alert the wearer to put his/her feet up for a while. Researchers estimate that about threequarters of diabetes-related amputations might be avoided with this kind of simple warning system. Smart socks are another example of the growing push to make high-tech home medical devices a part of everyday lives. It means ‘health care is coming home again’. This is one of the most rapidly growing segments of medical technology. It's driven by an aging baby boomer population, pressures to control health spending and the availability of new technology to implement decentralized care [10].
The Smart Bra
Scientists at the University of Wollongong in Australia are developing a 'smart bra' that will change its properties in response to breast movement, giving better support to active women when they need it most. Crafted from a new generation of intelligent fabrics, the ultimate Smart Bra will tighten and loosen its straps, or stiffen and relax its cups, to restrict breast motion, preventing breast pain and sag. Predicted to outperform any existing bra in the support stakes, it will encourage more women back to sports, and in extreme cases, stop clavicles snapping from the sudden movement of excessively heavy breasts. Fabric sensors attached to the straps and midriff of a standard bra, worn by a model in motion, will monitor breast movement and relay data in real time to a computer via a telemetry system. Information gathered from the tests will eventually be stored on a tiny microchip that will serve as the 'brain' of the ultimate Smart Bra, signaling the polymer fabric to expand and contract in response to breast movement. The Smart Bra is the first in a suite of smart textiles projects conducted by researchers from the University's internationallyrenowned Intelligent Polymer Research Institute (IPRI) in conjunction with the Biomechanics Research Laboratory [11].
Other Interesting "Smart Clothing"
There are also other "Smart Clothes" that are aimed at consumer use. For example, Philips, a British consumer electronics manufacturer, has developed new fabrics, which are blended with conductive materials that are powered by removable 9V batteries. These fabrics have been tested in wet conditions and have proven resilient and safe for wearers. One prototype that Philips has developed is a child's "bugsuit" that integrates a GPS system and a digit camera woven into the fabric with an electronic game panel on the sleeve. This allows parents to monitor the child's location and actions. Another Philips product is a life-saving ski jacket that has a built in thermometer, GPS, and proximity sensor. The thermometer monitors the skier's body temperature and heats the fabric if it detects a drastic fall in the body temperature. The GPS locates the skier, and the proximity sensor tells the skier if other skiers are nearby. Philips suggests that wearable computers will be widely used by the end of the next decade [10].
Conclusion
Intelligent medical clothing and textiles have the potential to substantially change the provision of health and health care services for large population groups, e.g. those suffering from chronic diseases (such as cardiovascular, diabetes, respiratory and neurological disorders) and the elderly with specific needs. Smart sensor systems and new approaches to analyse and interpret data together with cost-effective telematics approaches can fundamentally change the interface between citizen/patient and the health care provider. Biomedical clothing and functional textiles were believed in the workshop to be a key enabler technology for cost-effective disease management as well as for prevention. Fitness and health are trendy and are becoming a life style. Medical fashion (rather than clothes) offers a unique opportunity to seamlessly integrate health care into the daily lives of citizens [2].
In future e-Textiles, sensing, processing and communication capabilities are integrated in a woven structure to monitor biomechanical variables and physiological signals. This requires research on new fibre electroconductive materials. This kind of products could even make virtual medical exams possible. A patient would wear one of the shirts and a physician could monitor the vital signs from a remote location via the Internet. When incorporated into the design of clothing, the technology could quietly perform an ECG, monitor the wearer's heart rate, respiration, temperature, blood pressure and a host of other vital functions, alerting the wearer or physician if there is a problem [12].
The idea is great but several factors must be more considerate. The data communications between smart shirt and personal status monitor can be burst during combat scenario. Therefore, a delicate wireless communication protocol must be carefully designed and implemented. The power consumption of these garments must be addressed. Also since each human is unique somebody may have rapid heart rates and some don’t. So there should be no general standards to judge whether a man’s life is in dangerous situation. Instead at server (PSM-Personal Status Monitoring) side, it shall keep all records that smart products send back, then server can make more proper decisions by comparing those data. Which means not only the smart medical clothes should be tailored (size, position of sensor etc.), the entire systems should be tailored according to each unique constitution.
The smart medical clothes can be used in several distinct modes, in combat or field operations, in medical monitoring, for personal information processing. It’s predicted that not all of them need to be connected to the air all time. For privacy reason, sometimes it is much better to include a memory card to record everything on the garment then send all information to PSM. These data can be used whenever needed. Another important reason is the health issue, sending data wireless means electromagnetic wave and the impact of it to the bodies is not known yet.
At last, the cost for maintenance is also a key factor. The smart medical clothes are high tech products and there are bus connectors all over the garment. What can be done if there is a crack? More specifically, during battle for example, the ability to recover smart clothes in a short time is important. This might be solved by wireless interconnection all sensor components and when a sensor is broken it should be possible to sew another [5].
The results of the researches will indeed make a positive impact on the quality of life for individuals in the real world. While still in an embryonic stage, the smart and functional textile technology has the potential to become ubiquitous.

References
[1] http://www.icewes.net/projdetails_haupt.htm
[2] http://www.hoise.com/vmw/02/articles/vmw/LV-VM-08-02-35.html
[3] http://ldt.stanford.edu/~jeepark/jeepark+portfolio/cs147hw8jeepark.html
[4] http://www.techtv.com/freshgear/products/story/0,23008,3348594,00.html
[5] http://nesl.ee.ucla.edu/courses/ee202a/2002f/submissions/hw3/Jea_David/HW3.pdf
[6] http://www.darpa.mil/dso/success/smashirt.htm
[7] http://www.sensatex.com/smartshirt/index.html
[8] http://www.vivometrics.com/site/system_howitworks.html
[9] http://www.esapub.esrin.esa.it/buletin/bullet108/inbrief_108.pdf
[10] http://www.technologyreview.com/articles/upstream0901.asp
[11] http://www.uow.edu.au/science/research/ipri/smartbra.html
[12] http://popularmechanics.com/science/medicine/2000/9/underwear_doctor_aware.html

INTELLIGENCE IN TEXTILES The Next Step

Intelligent textiles represent the next generation of fibres, fabrics and articles produced to respond in time. It can be described as textile materials that think and act for themselves. This means, it has keep us warm in cold environments or cool in hot environments or provide us with considerable convenience in our normal day-to-day affair. Intelligent textiles are not confined to the clothing sector alone. It is used in protection, safety, added fashion and convenience. The most important intelligent materials at present in are classified as 1) Phase change materials, 2) Shape memory materials, 3) Chromic materials 4)Conductive materials and 5)Electronics incorporated textiles.

Phase Change Materials (PCM)
Every material absorbs heat during heating process and its temperature will rise constantly. The heat stored in the material is released into the environment through a reverse cooling process and the material temperature decreases continuously. A normal textile material absorbs about one kilo joule per kilogram of heat while its temperature rises by one degree Celsius. Phase Change Material (PCM) will absorb higher amount of heat when it melts. This thermo regulating effect of textiles can be obtained with the application of PCM.


Figure 1.describes the PCM incorporated clothing action A paraffin-PCM, absorbs approximately 200 kilojoules per kilogram of heat if it undergoes a melting process. During the complete melting process, the temperature of the PCM and its surrounding area remains constant. The paraffin’s are either in solid or liquid state. In order to prevent the paraffin's dissolution in the liquid state, it is enclosed into small plastic spheres with diameters of only a few micrometers. These microscopic spheres containing PCM are called PCMmicrocapsules.
The microencapsulated paraffin is either permanently locked in acrylic fibres and in polyurethane foams or coated onto the surface of a textile structure. Normal garments do not balance the heat generated and released in to the environment from the body. PCM incorporated textiles provide good thermal balance due to its thermo regulating effect. PCM control the heat flux through the garment layers and adjusts the heat flux to the thermal circumstances, for example, if the heat generation of the body exceeds the possible heat release through the garment layers into the environment, the PCM will absorb and store this excess heat. On the other hand, if the heat release through the garment layers exceeds the body's heat generation during lighter activities, the heat flux through the garment layers is reduced by the heat emission of the PCM. The figure2 shows the thermoregulation effect of PCM incorporated clothing over the conventional clothing.

Intensity and duration of the PCM's active thermal insulation effect depend mainly on the heat storage capacity of the PCM-microcapsules and the applied quantity. Thin high-density materials support for cooling process. Thick and less dense textile structure leads to more efficient heat release. To ensure a suitable and durable active thermal insulation effect in an active-wear garment, it is necessary to apply the correct PCM in the appropriate quantity. The selected PCM is normally microencapsulated and incorporated in a textile substrate. Requirements of the textile substrate in a garment application include sufficient breath ability, high flexibility and mechanical stability. The substrate incorporated with PCM-microcapsules needs to be integrated into a suitable location of the garment design and certain design principles need to be taken into account.
Shape Memory Polymers(SMP)
These types of materials can revert from the current shape to a previously held shape, usually due to the action of heat. This technology has been extensively pioneered by the UK Defense Clothing and Textiles Agency. When these shape memory materials are activated in garments, the air gaps between adjacent layers of clothing are increased, in order to give better insulation. The incorporation of shape memory materials into garments thus confers greater versatility in the protection against extremes of heat or cold. Shape memory alloys, such as nickel-titanium, used to provide increased protection against sources of heat, even extreme 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. 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. In consequence, considerably improved protection against external heat is provided. For clothing applications, the desirable temperatures for the shape memory effect to be triggered will be near body temperature. Polyurethane films, which can be incorporated between adjacent layers of clothing. With temperature of the outer layer of clothing has fallen sufficiently, then polyurethane film responds so that the air gap between the layers of clothing becomes broader. Bi-Material Film laminates rely on differing coefficients of thermal expansion to produce a reversible bending effect. Encapsulated Bi-Gels absorb liquid at differing rates according to temperature, which causes them to bend used to actuate variable insulation system. Other uses of SMPs in domestic purpose are in shower mixer valves, coffee makers, rice cookers, safety shut off valves for fuel lines in the event of fire and in air conditioning systems.
Chromic Materials
Chromic materials are the general term referring to materials which radiate the color, erase the color or just change it because its induction caused by the external stimuli, as "chromic" is a suffix that means color. It can be classified depend on the Stimuli. Out of this the first four chromic materials are important and has potential to cater the market
• Photochromic: external stimuli energy is light.
• Thermochromic: external stimuli energy is heat.
• Ionochromic: external stimuli energy is pH value
• Electrochromic: external stimuli energy is electricity.
• Piezorochromic: external stimuli energy is pressure
• Solvatechromic: external stimuli energy is liquid.
• Carsolchromic: external stimuli energy is electron beam.
Photochromic :
In this kind of chromism the color change is due to the intensity of the light(UV radiation also). The photochromic dyes interact with the electromagnetic radiation in the near UV (300 400nm),Visible(400- 700nm) and near IR(700-1500nm) to produce verity of effects, which is reversible when the radiation is withdrawn. Photochromism is of Two types. Positive and Negative. In Positive Photochromism the colorless substance converted in to colored object when exposed in to the light due to Uni-molecular reaction system. Bi molecular reaction system is called Negative Photochromism i.e. from colored to colorless. the transformation is between two states that have different absorption spectra. It may be induced in one or both the direction by electromagnetic radiation. This process is a non destructive process., but side reactions may occur. Oxidation is the major cause for the degradation of the Photochromism. Main class of Photochromism is Spiropyrans. It is used in Optical switching data and Imaging system rather then the textile applications.
Thermochromic:
Thermally induced reversible color change occur in the thermochromism. A large variety of substrates such as Organic ,Inorganic Orgonomatallic and Macro molecular systems exhibit this phenomena. Mercury Iodide salts like Ag2 HgI4 shows color change from yellow to orange at 51°C.This is due to the reason that each compound can under go phase change at particular temperature .Majority of thermochromic systems are unacceptable simply because of the change in the color requires large amount of energy due to involvement of inter molecular transformation. Using verity of liquid crystals ,it is possible to achive significant changes in the appearance over the narrow temperature range(5-15°C) and to detect small variation in the temperature(C1°C).The thermochromic dyes used extensively in the printing of Textiles, Micro encapsulation ,coating or dope dyeing .
Ionochromic dye:
These chromic materials are sensitive to pH. Widely used these classes dyes are Phthalides, Triarylmethans and Fluorans. In analytical chemistry these dyes are used extensively. There are no commercial application of these dyes in textiles but direct thermal printing can be used. In this process substrate contain both the color former and acid co reactant in a single layer. simply by heating the surface of the paper with a thermal head causes the components to react and to produce color.
Electochromic dye:
The material that change color upon the application of Voltage are called electrochromes. This is due to oxidation and reduction process with in the electochromic material. This are of three types. First type, the coloring species remain in the solution. In the second type the reactants are in solution but the colored product is of solid. In the third type is both reactant and the color is in form of solid e.g. composite Film. Most available electochromic dyes are of inorganic oxides such as cobalt oxide, nickel oxide, molybdenum trioxide. A research is going on in MIT,USA to use thin film composite electrode material with layer by layer assembly technique, to identify whether electrochemical cell is fully charged or discharged by using color change. The most important commercial application of the electrochemic dye in the textile is of US-Military IR camouflage material (Dynam IR®) .
Solvantochromic dye:
The Solvantochromism is a reversible variation of the electronic spectroscopic properties (absorption and emission)of a chemical species, induced by the solvents. It is one of the oldest chromism have been described as long as ago 1878.This is used as probes for application in polymer characterization. Where they can be used to look for localized polar features at the molecular level. Chromic dyes contain highly specialized components that require extraordinary careful manufacturing technique and has great potential for both fashion and higher end market.
Conductive materials
Exploration of human/machine interaction and wholly new types of interface sensor technology has resulted in the development of sensory fabric. These materials also afford designers new opportunities in developing for product markets. The ability to dispense with fixed casings, rigid mountings and inflexible substrates facilitates new radical possibilities in flexible, user-friendly interfacing textiles. By using conductive plastics, pressure sensitive inks and piezo films the above application succeeded in textiles. The main emphasis is currently on X-Y position sensing and pressure sensors.
X-Y position sensing
The structures of these materials offer the capability of reading the location, within a fabric sheet (Pad), of a point of pressure (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-Y position. The Fabric structures that provides an X-Y position function can also be used to provide accurate 'switch matrix' functionality. Interpreting electronics are used to identify the location of switch areas in any configuration to suit product requirements. Since this is done in software, an endless array of configurations can be addressed at the touch of a piece of fabric.
Pressure sensors
Readings can be obtained from smart fabrics according 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. 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 a heat or energy source is needed as the conductive material is not able to generate energy, it is only capable of conduction, to distribute the heat throughout the entire garment or suit. The advantages and benefits that conductive materials over the existing wire system are uniform temperature distribution, pliability, strength (resistance to flex and stress), non-corrosive nature, and cost effectiveness.
Other Intelligent textiles
Stomatex®
Patterned new cold protection apparel. Cell foam materials such as neoprene and polyethylene can be used in the construction of garments. Stomatex® NE is ideal for close contour fitting apparel for unhindered body movement. Stomatex® PE is a lightweight apparel and has a significant cost advantage over neoprene. Stomatex® PE is suitable for use in multi-layered clothing systems and footwear where weight may be an important factor.
Hydroweave®:
Patterned product is meant for comfortably in extreme cold and wet condition. Super water-absorbing polymer fibre blended into fibrous matting, this matting is positioned between a breathable exterior shell and a conductive, waterproof inner lining. The breathable outer shell can be made from a variety of woven or knitted fabrics to deliver the performance needed for a wide range of applications. The inner lining is a thermally conductive micro-porous membrane. This special material allows perspiration to escape, and keeping the wearer cool and dry. The advantages are
• Evenly distributes cooling effect over the entire fabric.
• Flexibility.
• Wearer will feel good comfort.
• Machine-washable.
• Re-usable.
Photonic fibres:
Dielectric mirror alternative layers of two materials with different refractive indices produce Photonic band gap. It reflects light in a certain range of wavelength and absorb light out side this range this fibres can be woven in to a fabric to form shields and filters in military operations. Bar codes made with this fibre are authentic.
Electronic systems incorporated in Textiles
There have been some very exciting developments recently regarding clothing with electronic systems incorporated into the constituent fibres and fabrics. Some examples of this are:
1.Music t-shirts- they allow to the wearer listen his/her favorite music stored on a chip, or to tune into the favorite radio station. They can also have moving images on the back.
2.Businessman garments-, which has a microphone, incorporated in the collar, a display, and a personal digital assistant in the sleeve.
3.Solar energy re-charge jacket- it includes some tools for creative playing and communication, such as a camera, display and microphone attachments.
4.Massage kits- It gives a soothing massage to the wearer that can be regulated depending on the level or relaxation desired by the user by applying vibration and pressure.
Summary
In the coming years, clothing products will increasingly assume intelligent functions. Clothing will combine the functions of medium, carrier and interface for an extremely wide range of micro system applications. This new generation of "intelligent textiles" places considerable new demands on innovative ability within the clothing industry, demands which also offer huge potential for future business sectors.
Reference:
1. http://www.electrotextiles.com/
2. http://www.gorix.com
3. http://www.dupont.com/afs/aracon/
4. http://www.stomatex.com/
5. http://www.hydroweave.com

Materials For Electronic Textiles

XS Labs is a design research studio based in Montreal, where we develop electronic textiles and reactive garments. We are concerned with the exploration of simple interactions that emphasize expressive qualities of electronic circuits and of the body. We define electronic textiles as “textile substrates that incorporates capabilities for sensing (biometric or external), for communication (usually wireless), power transmission, and interconnection technology to allow sensors or things such as information processing devices to be networked together within a fabric.”3 An important technical consideration comes from the fact that conductive materials used in traditional electronics, such as wires or printed conductive traces on a circuit board, need to be replaced with similarly conductive materials that can more easily be integrated into a textile. We replace some of the wires and other connections with different kinds of conductive threads that can be woven, stitched, or embroidered into the flexible textile substrate. Conductive threads are usually spun or twisted with conductive material (such as strands of silver or stainless steel).

Conductive threads and textiles
Since the field of electronic textiles is in its infancy, we have to be very creative in sourcing these conductive materials. When searching for conductive threads, we come across sources that include information for repairing fencing vest (which are conductive to aid in keeping score4) as well as suppliers who sell conductive textiles and threads used for electromagnetic shielding5. We have also found several American and European companies developing new and traditional metallic fibers for a variety of medical, aerospace, and industrial applications, such as Bekaert, a Belgian company that develops an array of high tech products in advanced metal transformation and advanced materials and coatings.6. We need to think outside the box and re-appropriate these products to create electronic textiles.

The Animated Quilt

The Animated Quilt (AQ) is a dynamic quilt whose square swatches change color over time. This electronic textile can display different patterns and change from one pattern to another, producing a smooth transition between different designs and images. There is a conscious effort to ensure that the aesthetics of the display mirror the soft qualities of the construction. AQ changes in a slow and contemplative way, referencing the process of weaving, knitting and other textile construction techniques. Resulting imagery blurs the boundaries between digital image and textile surface. The aesthetic of the patterns and the animation references the concept of pixel, traditional quilting and embroidery practice, as well as emerging research in visual display technology. The slowness and subtlety of the piece references and is critical of the fact that current technological development is largely focused on speed and hard edges. The very concept of a textile display is innovative and challenging in a field where such devices are traditionally hard, square and emissive devices. Textiles, on the other hand, have a uniquely intimate relationship with the human body. Designers of electronic textiles need to focus on personal expression and the social, cultural and economic history of textiles instead of striving to replace (or “augment”) human experience. In a time that is more and more dominated by the visual image and the cult of communication, this textile will also have the ability to display our needs and desires, as well as our artworks.
How it Works:
This functionality is accomplished through the development of a good intuition and understanding of the potential and limitations of electronics as well as the properties of conductive threads and textile constructions. Using traditional construction techniques, together with some unusual materials, the AQ deploys a simple technology for non-emissive, color-change textiles. It is a quilted “soft screen”. The materials we used include conductive threads and fabrics, thermochromic inks, and custom electronics components. The goal is to achieve a seamless integration of technology into the tradition of textile design and fabrication techniques.
Conductive threads
Conductive threads are either spun or twisted and incorporate some amount of conductive material (such as strands of silver or stainless steel) to enable electrical conductivity. These yarns can have various electro-mechanical properties. They can be woven, knit, or felted together with non-conductive yarns to create the substrate for an electronic textile. Recently, the heating of fabric using conductive yarns and threads woven into the textile has been demonstrated for the purpose of keeping people warm. We use conductive threads in two different ways: (1) to embroider a specific pattern on the surface of each pixel to allow us to heat it and change its color and (2) to transmit electricity from the controller board to each pixel.
Thermochromic pigments
Thermochromic materials have different color states at different temperatures. They literally change color when heated. They are an example of a non-emissive “active material”, together with photochromics, electrochromics, or shape memory alloys. Nonemissive materials are materials that do not emit light. Thermochromic leucodye materials are especially interesting because they can be engineered to change from a specific color to a clear state at an arbitrary temperature between 13°F (-25°C) and 150°F (66°C). A wide range of colors is available and unexpected color changes can be obtained by combining thermochromic inks with regular ones. By mixing inks that change at different temperatures, a more complex effect can be achieved. The inks can be applied with a number of printing processes, including screen-printing.
One major issue discovered over the time it took to create this piece is the relatively short life expectancy of thermochromic inks when exposed to natural light. UV radiation deteriorates the pigments over a period of months and the inks become less saturated and start losing their color-change abilities.
In existing products, color change is activated by body heat. AQ, on the other hand, uses resistive heating to create the change in temperature. We allow current to flow through embroidered conductive threads that have some degree of resistance. Resistance is the measure of how much an object impedes the flow of electricity. If we allow current to flow through a resistive material, the current will lose energy as it struggles to get through the material and the current's lost energy will become thermal energy in the material. The higher an object's resistance, the less current will flow through it.
Control electronics
AQ has 100 fabric pixels arranged in a 10 by 10 matrix. Each piece of fabric is individually addressable (with conductive threads) and can be controlled to slowly change color from black to white and back again, passing through a whole range of grayscale values. Each color change is programmed in the custom electronics board or controlled in real time when the display is connected to a desktop computer through the serial port. Control electronics are necessary to drive the textile display. The term refers to a printed circuit board (PCB) with various electronic components that is used to send power to different areas of the electronic textile in order to activate the thermochromic inks.

Saturday, December 29, 2007

SOFT COMPUTATION

Electronic textile research is still in its infancy, but we can clearly see several important research directions that suggest appealing near future applications. Some of the more important efforts include applications that (1) aid in patient health monitoring through sensor-embedded garments that track and record biometric data, (2) help improve athletic performance both by analyzing sensor data and by adapting to changing conditions so as to improve performance over time, (3) provide environmental sensing and communication technologies for military defense and other security personnel, and (4) present new structural and decorative solutions for fashion design. We are naturally most interested in this fourth direction and, since fashion is predominantly visual, we are particularly interested in developing technologies that will enable the construction of garments that have the ability to change color, texture, transparency, or shape over time. The field of textile design, (including weaving, felting and embroidering) which involves the creation of many complex patterns from different colored yarns, threads or fibers, is centuries old.
Today, efforts are being made to create flexible, fully addressable displays on fabric and textiles, which will allow a textile to display any pattern. Designers and consumers alike are quite excited by the future vision of a world populated with magical garments that can adapt and respond to various interaction parameters and change based on time of day, mood, or the designer’s whim. This vision is predicated on the technological development of visually animated materials that can be embedded or incorporated in a fabric. Existing materials for display usually “light up”: light emitting diodes (LEDs), electroluminescent (EL) material, or woven optical fibers transmitting the light of high brightness LEDs offer potential for wearable displays or animated fashion. Non-emissive materials such photochromic pigments (which change color when exposed to light) or thermochromic pigments (which change color when exposed to heat) are materials that simply change color and offer more interesting and more subtle possibilities for colorchange
textiles.