The MAIN Shirt: A Textile-Integrated Magnetic Induction Sensor Array


By : Daniel Teichmann,  Andreas Kuhn, Steffen Leonhardt and Marian Walter

Abstract: A system is presented for long-term monitoring of respiration and pulse. It comprises four non-contact sensors based on magnetic eddy current induction that are textile-integrated into a shirt. The sensors are technically characterized by laboratory experiments that investigate the sensitivity and measuring depth, as well as the mutual interaction between adjacent pairs of sensors. The ability of the device to monitor respiration and pulse is demonstrated by measurements in healthy volunteers. The proposed system (called the MAIN (magnetic induction) Shirt) does not need electrodes or any other skin contact. It is wearable, unobtrusive and can easily be integrated into an individual’s daily routine. Therefore, the system appears to be a suitable option for long-term monitoring in a domestic environment or any other unsupervised telemonitoring scenario.

image

image

For full article please click on the following link.

The MAIN Shirt: A Textile-Integrated Magnetic Induction Sensor Array

USE OF ZINC OXIDE NANO PARTICLES FOR PRODUCTION OF ANTIMICROBIAL TEXTILES


By:  R. Rajendran, C. Balakumar, Hasabo A. Mohammed Ahammed, S. Jayakumar, K. Vaideki and E.M. Rajesh

The application of nanoscale materials and structures, usually ranging from 1 to 100 nanometers (nm), is an emerging area of nanoscience and nanotechnology. Synthesis of noble metal nanoparticles for applications such as catalysis, electronics, textiles, environmental protection, and biotechnology is an area of constant interest. Recently, an awareness of general sanitation, contact disease transmission, and personal protection has led to the development of antimicrobial textiles. The development of antimicrobial cotton fabrics using Zinc oxide nanoparticles has been investigated in this present work. The ZnO nanoparticles were prepared by wet chemical method and were directly applied on to the 100% cotton woven fabric using pad-dry-cure method. The antibacterial activity of the finished fabrics was assessed qualitatively by agar diffusion and parallel streak method, quantitatively by percentage reduction test. The topographical analysis of the treated fabric and untreated fabric were studied and compared. The results show that the finished fabric demonstrated significant antibacterial activity against S. aureus in both qualitative and quantitative tests. The SEM analysis revealed the embedding of ZnO nanoparticles in treated fabrics. The wash durability study of the treated fabric was also carried out and found to withstand up to 25 wash cycles.

To download full article please click on the following link

Use of zinc oxide nano particles for production of antimicrobial textiles

EVALUATION OF ANTIBACTERIAL ACTIVITY OF ZnO NANOPARTICLES COATED SONOCHEMICALLY ONTO TEXTILE FABRICS


By: Gagandeep Singh, Eadaoin M. Joyce*, James Beddow and Timothy J. Mason

Growing resistance of microorganisms to potent antibiotics has renewed a great interest towards investigating bactericidal properties of nanoparticles and their nanocomposites as an alternative. In the present work studies have been carried out to investigate the antibacterial properties of ZnO nanoparticles (NPs). Various tests were performed to assess the antibacterial activity of cotton fabrics coated with ZnO nanoparticles against Gram positive Staphylococcus aureus and Gram negative Escherichia coli. The antibacterial activities of the fabrics were assessed semi-quantitatively by the agar diffusion method and the shake flask method (nutrient broth) and quantitatively by the shake flask method (saline) and the absorption method (ISO 20743:2007). The results showed a significant antibacterial activity of ZnO nanoparticles coated onto fabrics against both bacteria, with a slightly higher activity against Staphylococcus aureus as compared to Escherichia coli.

To download full article please click following link

EVALUATION OF ANTIBACTERIAL ACTIVITY OF ZnO NANOPARTICLES COATED SONOCHEMICALLY ONTO TEXTILE FABRICS

SPECIFICATIONS/PROPERTIES REQUIRED FOR THE MEDITECH PRODUCTS AND THEIR TESTING


By: – T.Sureshram
Junior Scientific Officer, Department of Textile Physics,
The South India Textile Research Association, Coimbatore-14

Combination of textile technology and medical sciences has resulted into a new field called medical textiles. Medical textiles are one of the most rapidly expanding sectors in the technical textile market. Textile materials in the medical textile field gradually have taken on more important roles. The wide range of textile products used in the medical industry are classified in to four major segments namely non-implantable materials, implantable materials, extracorporeal devices and healthcare & hygiene products. This paper deals with the specifications/properties required and different types of test methods involved for evaluating the characteristics of the medical textile products.

To download full article please click on the following link

Testing Specification

Using the Physics of Acoustics to Reduce Weight in Cars


As automotive manufacturers continue to push for improved fuel consumption and lower carbon emissions, they are squeezing every single gram of weight out of every single part that goes into a car.  Meanwhile, however, the pressure to save money and create a smoother, quieter driver experience is also increasing. Greensboro, North Carolina headquartered Precision Fabrics Group, has commercialized a unique nonwoven fabric called Nexus AFR which helps solve the car makers need to improve acoustics and reduce weight without breaking the bank. Physics of acoustics The Precision Fabrics solution is based on the ‘physics of acoustics’ and the science focuses on two dominant properties in part design – thickness and resistance to airflow.  Because sound moves through air in waves of minute pressure variations, the solution has to work for long wavelengths (low frequency) and for short wavelengths (high frequency). The frequency of sound, the wavelength of sound, and the speed of sound are related The thickness of the existing insulation layer is important and determines what low frequency wavelengths can be absorbed.  The new Nexus AFR nonwoven material replaces the traditional black scrim on the surface and controls the mid and high frequency wavelength by managing the sound pressure level variations and ‘trapping’ the energy in the insulation layer of the part.  This makes the composite more efficient than just the Homogeneous insulation material by itself.

Advantages over traditional homogeneous insulation

According to Precision Fabrics’ Richard Bliton, this two material approach has many advantages over the traditional homogeneous insulation, one material approach. “Traditional black scrim – the commodity black scrim used in the auto industry is a descendent of the fabric interlining and lining materials.  The typical nonwoven manufacturing technology is a chembond or thermalbond technology,” explains Bliton. Low cost fibres are carded and oriented primarily in the machine direction and a chemical spray or waterfall coats the web and it is compressed and dried.  The web then has a hot melt adhesive powder sprinkled on the face which is to be reactivated during on processing.  Properties such as FR or repellency can be added to the waterfall treatment. “The strength of this type of web is low compared to other nonwoven structures, but the prime advantage is that it is low cost.   Most of the purchasing specifications for this type of material only specify- fabric basis weight, colour, width, and amount of adhesive.  Acoustic characteristics such as Rayls are not controlled, tested or reported,” Bliton continues. An example, Bliton says, is an automotive hood liner.  A traditional design would have a 30 gsm black nonwoven scrim on the back (B) side, 1600gsm resonated fibreglass about 10mm thick as the insulation layer and a 50 gsm black scrim on the front (A) side. A recently launched next generation hood liner with Nexus AFR was made up of 30 gsm B side, 600 gsm Fiberglass insulation 10mm thick and 100 gsm Nexus AFR on the face.  The weight reduction is 950  grams/m² which is more than 2 lbs/m². In this particular case, the acoustics stayed the same and there was cost reductions generated in the raw material line, and additional improvements in manufacturing related to shorter cycle times required to mould a 600 gsm fibre glass part as compared to a 1600 gsm part. Alpha Cabin Random Incidence Sound Absorption

Automotive industry quick to adopt solution

According to Precision Fabrics Group, the automotive industry is moving quickly to implement this new approach. Parts using the AFR nonwoven are commercial in 10 platforms within 5 OEMs and one major OEM has adopted the low density fibreglass with AFR facing design approach as a worldwide corporate best practice. The focus on reducing weight and cost is one of the drivers for the adoption of the new material, but in some cases a vehicle may have a sound problem that has to be solved.  In these cases, the company says, a properly selected AFR facing can significantly improve that acoustic absorption of the part. The physics based solution offers the acoustic engineer some flexibility to tailor the part to focus the acoustic absorption on mid to high frequency ranges. “Some of the commercial parts on the road are last minute ‘fixes’ to acoustic problems found during pre-launch road tests.   The switch to an AFR facing is an easy change for a part manufacturer and an OEM to make,” Rich Bliton adds. The new fabric meets or exceeds all of the fabric specifications that are in place, the modified part can be made on the same tooling and the improved part will have the same fit as before. “The design approach to build a part with low density material for thickness and an acoustically tuned fabric facing for impedance as opposed to the traditional parts where performance was defined by the weight/thickness of the insulation is a new paradigm.  The science can be applied all types of insulation materials. Each situation will have to be tuned and validated, but early feedback is generating 30-40% weight reductions without loss of acoustic absorption performance,” Bliton concludes.

About Precision Fabrics Group

Precision Fabrics manufactures, markets and sells value-added products and services to selected, highly specified markets. The company’s high-performance products play a key role in several diverse markets, which demand engineered, finished fabrics, the common thread amongst which is  the technical nature of their requirements. Precision Fabrics was the first ISO-qualified textile supplier in the USA. – and ISO continues to provide the discipline and framework for effective and efficient product development, customer service, and manufacturing. Precision Fabrics has been ISO-registered to 9001 since 1993 and upgraded to 9001-2008 in October 2009. Precision Fabrics was created in 1988 via a leveraged buyout from Burlington Industries and continues as a privately-held company today. The company has evolved from a traditional textile company into an engineered materials business, focused on highly technical, high-quality woven and nonwoven fabrics. Today, Precision Fabrics employs approximately 600 people and operates plants in North Carolina, Virginia and Tennessee. Corporate headquarters are located in Greensboro, North Carolina and sales offices are maintained in Greensboro and in Bamberg, Germany. Precision’s Vinton, VA, Plant specializes in weaving some of the most technically challenging continuous-filament fabrics in the world. The Greensboro and Madison facilities are world-class in the range of nonwoven products that they produce.   Ref: http://www.innovationintextiles.com/using-the-physics-of-acoustics-to-reduce-weight-in-cars/

CONTRIBUTION OF TEXTILE TECHNOLOGY TO THE DEVELOPMENT OF MODERN COMPRESSED BANDAGES


Bandage
Bandage (Photo credit: Wikipedia)

 

BY: – SVETLANA MILOSAVLJEVIC & PETAR SKUNDRIC

 

Although compression therapy is a key factor in the  successful treatment of some circulatory problems in lower limbs, this form of therapy includes some risks if used inappropriately. Based on deliberate application of pressure to a lower limb, using a variety of textile materials, elastic or rigid in order to produce a desired clinical effects,  modern compression therapy presents a good sample of successful penetration of textile technology into the phlebology field of medicine. However, although compression therapy has been in use for over 150 years, there exists a low awareness among practitioners and patients on the product usage, application techniques and benefit of appropriate selection of bandages for determined types of leg venous diseases. Also, not all manufacturers for compression textile materials seem to be conscious of end-users need. simultaneously, impressive developments in the field of elastic fibers and modern knitting and weaving technologies, offer chances for realization of completely new types of compressed bandages, capable of making an important contribution to the management of venous disease. In this review, starting from brief account of pathogenesis and the presentation of compression therapy principle, an account of the contribution of all sectors in the textile technology chain to a modern compression therapy is given.

 

To download full article please click following link.

 

 

contribution of TT to the development of modern compression bandages

 

ELECTRONIC TEXTILES: Wearable Computers, Reactive Fashion and Soft computation


Electronic textiles, also referred to as smart fabrics, are quite fashionable right now. Their close relationship with the field of computer wearable‘s gives us many diverging research directions and possible definitions. On one end of the spectrum, there are pragmatic applications such as military research into interactive camouflage or textiles that can heal wounded soldiers. On the other end of the spectrum, work is being done by artists and designers in the area of reactive clothes: “second skins” that can adapt to the environment and to the individual. Fashion, health, and telecommunication industries are also pursuing the vision of clothing that can express aspects of people’s personalities,social dynamics through the use and display of aggregate social information.

In my current production-based research, I develop enabling technology for electronic textiles based upon my theoretical evaluation of the historical and cultural modalities of textiles as they relate to future computational forms. My work involves the use of conductive yarns and fibers for power delivery, communication, and networking, as well as new materials for display that use electronic ink, nitinol, and thermochromic pigments. The textiles are created using traditional textile manufacturing techniques: spinning conductive yarns, weaving, knitting, embroidering, sewing, and printing with inks.

image

To download click following link.

textile-berzowska

Innovations in fibres and textile materials for sportswear


Fibre developments

The evolution of fibre developments has gone through the phases of conventional fibres, highly functional fibres and high-performance fibres. Polyester is the single most common fibre used for sportswear and active wear. Other fibres suitable for active wear are polyamide, polypropylene, acrylics and elastanes. Wool and cotton fibres are still finding applications in leisurewear. Synthetic fibres can either be modified during manufacture, e.g. by producing hollow fibres and fibres with irregular cross-section, or be optimally blended with natural fibres to improve their thermo-physiological and sensory properties. Synthetic fibres with improved UV resistance and having anti-microbial properties are also commercially available for use in sportswear.

Improved fibre spinning techniques in melt spinning, wet spinning, dry spinning as well as new techniques such as gel spinning, bi-component spinning and microfibre spinning, have all made it possible to produce fibres, yarns and fabrics with unique performance characteristics suitable for use in sportswear and sports goods. New technologies for producing microfibres have also contributed towards production of high-tech sportswear.

By using the conjugate spinning technique, many different types of sophisticated fibres with various functions have been commercially produced  which has resulted in fabrics having improved mechanical, physical, chemical and biological functions. The technique of producing sheath/core melt spun conjugate fibres has been commercially exploited for producing added-value fibres. Unitika produced the first heat-degenerating conjugate fibre with a core containing zirconium carbide (ZrC). Since ZrC absorbs sunlight (visible and near-infrared radiation) and emits far-infrared radiation, one feels warmer when one puts on a jacket made from such fibres. Other types of heat-generating fibres contain ceramic micro-particles.

High-performance fibres

Today, a wide range of high-performance fibres is commercially available for technical and industrial applications. These types of fibres are used in sports protective wear/equipment developed for impact protection and in textile reinforcement in sports products for different applications. Among the speciality fibres already established are the following:

Aramid fibres:

± p-aramid fibre to provide high strength and ballistics
± m-aramid fibre to provide flame and heat resistance.

Ultra-high tenacity polyethylene fibres (UHMWPE).

Gel spun, ultra-high molecular weight polyethylene fibres with extremely high specific strength and modulus, high chemical resistance and high abrasion resistance.

Polyphenylene sulphide fibres (PPS).

Crystalline thermoplastic fibre with mechanical properties similar to regular polyester fibre. Excellent heat and chemical resistance.

Polyetheretherketone fibres (PEEK).

Crystalline thermoplastic fibre with high resistance to heat and to a wide range of chemicals.

· Novoloid (cured phenol-aldehyde) fibres.

High flame resistance, non-melting with high resistance to acid, solvents, steam, chemicals and fuels. Good moisture regain and soft hand.

· PBO (p-phenylene-2,6-benzobisoxazole) fibres.

The strength and modulus of this fibre exceed those of any known fibres.

Highly functional fabrics

There has been a strong growth in the development and use of highly functional materials in sportswear and outdoor leisure clothing. The performance requirements of many such products demand the balance of widely different properties of drape, thermal insulation, barrier to liquids, antistatic, stretch, physiological comfort, etc. The research in this field over the past decade has led to the commercial development of a variety of new products for highly functional end-uses. By designing new processes for fabric preparation and finishing, and as a result of advances in technologies for the production and application of suitable polymeric membranes and surface finishes, it is now possible to combine the consumer requirements of aesthetics, design and function in sportswear for different end-use applications. The fabrics for active wear and sportswear are also specially constructed both in terms of the geometry, packing density and structure of the constituent fibres in yarns and in terms of the construction of the fabric in order to achieve the necessary dissipation of heat and moisture at high metabolic rates. Many smart double-knitted or double- woven fabrics have been developed for sportswear in such a way that their inner face, close to human skin, has optimal moisture wicking and sensory properties whereas the outer face of the fabric has optimal moisture dissipation behaviour.

In addition to the innovations in highly functional man-made fibre-based fabrics, advances have also been made in cotton and wool fabrics for sportswear. An example is the development of `Sportwool’ weatherproof technology, where the constituent fibre, yarn and fabric properties and the fabric finishes of `Sportwool’ are supposed to create a drier and cooler microclimate.

Since the introduction of Gore-Tex fabric in 1976, a variety of lightweight breathable highly functional fabrics have been developed worldwide. Highly functional fabrics are generally characterized as being waterproof/moisture permeable, sweat-absorbing and with high thermal insulation at low thickness values. These fabrics are now extensively used in making sportswear and sports shoes. One can say that these products are basically complex materials with diverse functions. In many of these products the requirements of comfort and fashion have successfully been integrated with segmentation in uses.

Important developments are envisaged in making multifunctional coated or laminated fabrics for different applications. For example, some new innovative functional textiles for protective clothing were recently introduced by W. Gore and Associates. Gore-Tex Airlock is a functional textile which was developed by Gore for the special needs of firefighters. The concept of this product is to eliminate the conventional, bulky, thermal insulation layer and substitute it by a protective air cushion. Dots consisting of foamed silicone are discontinuously applied to a fibre substrate and anchored within the microporous Gore-Tex membrane. They measure only a few millimetres in height, creating a defined air cushion between the adjacent flame-retardant face fabric and the inner lining. This laminated fabric is characterized by thermal insulation, breathability, perspiration transport, absorption and quick-dry properties.

Biomimetics and textiles

The structure and functions of natural biological materials are precise and well defined. The imitation of living systems, `biomimetics’, could make it possible in future to replicate the molecular design and morphology of natural biological materials since their structure and functions are related. Already in many laboratories around the world, R&D work is going on in the field of biomimetic chemistry and fabric formation. A typical example is the development of water- and soil-repellent fabrics produced by imitating the surface structure of a lotus leaf. Water rolls like mercury from the lotus leaf, whose surface is micro-
scopically rough and covered with a wax-like substance with low surface tension. When water is dropped on to the surface of a lotus leaf, air is trapped in the dents and forms a boundary with water.

Intelligent textiles

There have been some interesting developments taking place regarding intelligent textiles and interactive materials with great market potential in the sportswear sector. These materials readily interact with human/environmental conditions thereby creating changes in the material properties. For example, the phase-change materials and shape-memory polymers embedded in fabric layers will be able to interact with a human body and produce thermoregulatory control by affecting the microclimate between the clothing and the human skin. In addition to the two dimensions of functionality and aesthetics, if `intelligence’ can be embedded or integrated into clothing as a third dimension, it would lead to the realization of protective and safety clothing as a personalized wearable information infrastructure.

Reference: “Textiles in sports” by R.Shishoo

CURRENT AND FUTURE TECHNOLOGIES FOR WEARABLES AND E-TEXTILES


The technologies embedded in wearables influence the comfort, wearability and aesthetics. According to Tao (2005) (Figure 1) a typical system configuration of a wearables includes several basic functions such as: interface, communication, data management, energy management and integrated circuits. This classification is based on general purpose wearable computers.

A similar classification is presented by Seymour (2009) with focus on fashionable wearables, a combination of aesthetic as well as functional pieces . Thus most common technological components used to develop fashionable wearables are: interfaces (connectors, wires, and antennas), microcontrollers, inputs (sensors), outputs (actuators), software, energy (batteries, solar panels), and materials (interactive or reactive materials, enhanced textiles).

Both classifications are overlapping each other, but for the purpose of this thesis they will be combined and all the concepts explained, with emphases on e-textiles. The project examples used in this section, supporting the theory are related to wearable textile technology already available on the market or projects currently being developed in research labs around the world showing promising results in becoming future technologies. The diversification of the project concepts goes from being very functional and practical towards more expressive and artistic.

Inputs

To obtain information for wearable devices components such as sensors are often used, for instance, environmental sensors, antennas, global positioning system receivers, sound sensors and cameras. Such sensors can be divided on active and passive(Langenhove & Hertleer, 2004)(Seymour, 2009). Active inputs are controlled by a user via a tactile or acoustic feedback system, which provides an intuitive interaction with the garment. Passive inputs collect biometric data from the human body as well as environmental data collected via wireless transmission system. The data is captured and further processed usually using a microprocessor. The table below provides suggestions for the type of inputs wearable systems can collect from a person or the environment.

Input Interfaces

The most common way for a user to interact with a device these days, involves the use of buttons, keyboards and screens, as they are proven to be easy to learn, implement and use with few mistakes. Fabric- based interfaces using keyboards and buttons are most common for wearables. They are usually designed from either multilayered woven circuits or polymer systems (Tao, 2005). At the dawn of ubiquitous computing environments, people will need to engage with many different devices with built-in microprocessors and sensors. As wearable devices become more complex, a need for more complex interfaces arises. People want more options on their devices, they want everything, but they also want them with the maximum of easy, freedom and comfort. This requires new ways of interaction, such as user engagement through voice, touch and gestures. The devices of the future will have no faces(Saffer, 2007). They will implement more intuitive ways of interaction.

Origin Inputs
Person Voice, visuals, pressure, bend, motion, biometric data, proximity, orientation, displacement, smell, acceleration
Environment Temperature, light, sound, visuals, humidity, smoke, micro particles

Figure 1 – Suggestions types of inputs that a wearable system can collect

Voice recognition – Voice-controlled interfaces are currently most common on phones. However there are few drawbacks in the technology. It is difficult to create voice-controlled interfaces in public spaces, from both technical and design perspective, when the system should always listen for a command. In this case, incorrect processing of information is possible due to large influence of background noise. How will the system know to differentiate between a command and a background noise is a design challenge that yet needs to be answered. Furthermore, the current voice recognition technology has a problem distinguishing between different people’s voice and additionally, it requires more processing power then previous technologies. Leading researchers believe these obstacles will be overcome as technology advances, predicting that in a very near future we will interact with voice – controlled devices and environments.

Gesture recognition – As devices gain better awareness of the movement of the human body through technologies such as Global Positioning System (GPS) sensors and sudden – motion sensors (SMSs), gesture recognition as a way of human interaction with devices is becoming even more achievable. Indeed, there are devices such as mobile phones equipped with tilt motion sensors, so that users can, for example, “pour” media data from their phone to another device (Dachselt & Buchholz, 2009). Donneaud (2007) created a large textile interface for playing electronic music. Figure 2 illustrates the textile interface that is constructed of two conductive fabrics which are fixed on a frame each one weaved with conductive threads in a different direction.

image

Figure 2: Textile XY: interface for playing music

When the performer presses any point of this textile, the two fabrics connect and the current electrical value is sent to the computer. This textile interface is flexibility and transparency, involving the whole body through choreographic movements in the musical interpretation, thus allowing the performer to explore the textile interface by look, touch and gesture.

Presence recognition – Person’s presence is another way of interaction with a system. Present- activated systems are one of the central research points for ambient intelligent environments. The main design and technical challenge here is what determines if the system should react to the presence of a person, how it should react and how fast this reaction should be after a change has been detected.

Outputs

There are a variety of output devices or materials which activate in wearables as a result of computation triggered by input data. Many outputs can stimulate any of the five the senses of the wearer or his audience. For example, shape memory alloy can change the silhouette of a fabric presenting a visual experience for an audience and a tactile experience for the wearer. The table below provides an overview of possible outputs to address specific senses.

Senses Outputs
Visual LEDs, EL wires, displays, photochromic ink, thermocromic ink, E-ink
Sound Speakers, buzzers
Touch Shape memory wires, conductive yarns, conductive fabric, motors/actuators
Smell and Taste Scent capsules

Figure 3 – Overview of possible outputs that address specific senses

Communication Technology

For electronic components to truly become part of bigger interactive systems they need to be connected in order to exchange information. Wires, cables, antennas and connectors are most common physical components used to connect electronics together. Wired connections are secure and practical in many cases, but they can cause inflexibility and add to the weight of the system. On the other hand, wireless connections increase flexibility and the lightness of the system, but increase its complexity.

The advances in wireless technologies have played a significant role in the development of wearables and e-textiles, reducing the number of devices attached to a system, simplifying its construction as well as minimizing the size. According to Seymour(2009) some of the most common wireless communication and location based systems are: UMTS (Universal Mobil Telecommunication System), GPRS (General Packet Radio Service), GSM (Global System for Mobile Communication), GPS (Global Positioning System), Cell Triangulation, WIFI, Bluetooth, IR (Infrared) and PAN (Personal Area Network). These communication systems can be further subdivided to long- range or short range communications(Tao, 2005), if the transfer of information is between two or more users via the internet or a network protocol or between two or more wearable devices worn by a user, respectfully.

Long-range communications

The long-range communication technologies advanced during the mobile revolution. All portable devices such as mobile phones, PDAs, MP3 players use radio frequencies to enable communication. From the list above the following communication systems: UMTS, GPRS, GSM, GPS, cell triangulation, WIFI are long-range. GSM is the communication system currently most suitable for voice transmission, as well as for data and files transmission at 9.6 kbps. For transfer of pictures and video a third-generation (3G) wireless system is also available, with the capacity of 384 kbps. GPS and cell triangulation is suitable for navigation purposes. The variety of communication systems opens many possibilities for wearable devices and the exchange of information.

Short-range communications

Short-range communication for wearables is a research area that still needs to be developed. Some of the approaches considered for implementation in wearables are wiring, infrared, Bluetooth technology, WIFI, Personal Area Network (PAN) and Fabric Area Network (FAN). Even though they have some disadvantages, they show promising results as future technologies embedded in devices and textiles.

Embedding wires in garments is cumbersome and constrictive, and therefore not adequate. For infrared to be effective it requires direct lines of sight, which is not practical and difficult to implement on different devices worn on the body. Bluetooth technology is widely used, with an open wireless communication protocol which ensures connection between several devices within a short communication range (10 m), overcoming problems of synchronization. This technology is embedded in a range of products (such as smart phones, headsets, mouse, keyboards, printers and game consoles) and has many applications in situations where low-bandwidth communication is required. Bluetooth devices can interact independently of the user, as well as advertise services they provide, thus making this network more secure than other types, as more of the security, network address and permission configuration can be automated. This also provides an easier access to services for the users. WIFI (also called “wireless Ethernet”) uses the same radio frequency as the Bluetooth, but with higher power, resulting with a stronger connection. The users have the advantage to move around within a broad coverage area and still be connected to the network, through a variety of WIFI enabled devices such as laptops, smart phones, PDAs.

From a collaboration research project in 1996 between MIT Media Lab and IBM Almaden Research Center a new wireless technology emerged called the Personal Area Network (PAN) also referred to it as Body Area Network. The technology is considered the backbone of wearable technology, allowing exchange of digital information, power and control signals within the user’s personal space. PAN takes advantage of the natural electrical conductivity of the human body combined with a transmitter embedded with a microchip, to create an external electric field that passes an incredibly tiny current (1 billionth of an amp- 1 nanoamp) through the body, used to transmit data (IBM, 1996). As a comparison, the electrical field created by running a comb through hair is more than 1000 times greater than the current required for PAN technology to be functional. The technology is still being refined but researchers see great potential in PAN, as an effective and cost-efficient communication network. Passing of simple data between electronic devices carried by two people would be easier than ever, such as exchanging business cards via a handshake. This scenario as fascinating as it sounds also imposes many security issues, because touching a person with a PAN is like tapping a phone line (Tao, 2005).

In 2001 Hum proposed a wireless communication infrastructure to enable networking and sensing on clothing called the Fabric Area Network (FAN). The technology promises to solve some of the problems Bluetooth and GSM are facing, regarding the public concern of health hazards from the increased amount of emissions in the body from these sources of radiation. The new and innovative method, in which the technology architecture is designed, uses radio frequency (RF) fields for data communication and powering, restricted only to the surface of the clothing thus eliminating radiation into the body. More specifically, the technology uses multiple radio frequency identification FRID links, which have been used in the industry for years for tagging and tracking products. Even though the technology is being promoted as emission-save, low-cost and easy to maintain, it still has much more development it needs to undergo before such networking and sensing clothing can be considered for mass production.

The technologies described above such as GSM, GPS, WIFI and Bluetooth are already widely used as part of wearable devices. Since, they have been proven to be stable communicational systems and well developed; attempts have been made in the research community for their implementation in computational and smart textiles. However, these technologies were not initially designed for integration in clothing and accessories and thus researchers are modifying and perfecting these wireless networks to meet the requirements that currently established communication systems, cannot fulfill. For that reason, wireless networks such as PAN and FAN were originally designed and are still investigated.

Data management technologies and integrated circuits

The storing and processing of data in wearables is carried out in integrated circuits (IC), microprocessors or microcontroller. Integrated circuits are miniaturized electronic circuits which are mostly manufactured from silicon because of its superior semi conductive properties. However silicon is not flexible and therefore ICs are not very suitable for incorporating them on clothing. Developing ICs from conductive or semi-conductive polymeric Having the properties of a polymermaterials can be of great importance for wearable electronics since these materials are flexible, lightweight, and strong and of low production cost (Rossi, Capri, Lorussi, Scilingo, Tognetti, & Paradiso, 2005). Their down side is that they are not as efficient as silicon, and thus scientists are looking into developing electronics in the near future that will be a combination of both silicon and conductive polymers which will be complimenting each other.

Among the most advanced integrated circuits there are the microprocessors which are the heart of any normal computer. Also known as the CPUs (Central Processing Units), they present complete computation engines fabricated on single chips. The microprocessor performs many functions some of which are executing a stored set of instructions carrying out user defined tasks as well as carrying the ability to access external memory chips to both read and write data from and to the memory. From the architecture of the microprocessors, more specialized processing devices were developed, such as microcontrollers.

A microcontroller is a single-chip computer, which is embedded in many everyday products and therefore it is also called “embedded controller”. If a product has buttons and a digital display, most likely it also has a programmable microcontroller that provides a real-time response to events in the embedded system they are controlling. Such automatically controlled devices, often consumer products, are remote controls, cell phones, office machines, appliances, toys and many more.

Even though microcontrollers are “small computers”, they still have many things in common to desktop computers or large mainframe computers. All computers have a CPU which executes many different programs. In the case of microcontrollers the CPU executes a single program and thus they are known as “single purpose computers”. Also microcontrollers have a hard disk, a RAM (random-access memory) and inputs and outputs, which are all combined on a single microchip. Other characteristics common for a majority of microcontrollers, besides being embedded inside other devices dedicated to run specific single task programs, are that they come as low-power devices, small and at low cost, which is of great importance for wearable e-textiles. While some embedded systems are very sophisticated, many of those implemented in wearable e-textiles have minimal requirements for memory and program length, with no operating system and low software complexity. The actual processor used in the microcontrollers can vary widely, where ones choice when designing interactive applications depends on the context in which the embedded system will be used. The programs running on the microcontrollers can be stand-alone or can communicate with the software running on other external devices, preferably through a wireless network.

Energy management technologies

One of the biggest problems in wearable and integrated electronic technology is power and the quest for alternative energy sources is essential. Today batteries in the form of AA batteries or lithium batteries are the most common source of energy utilized for running embedded systems and processing of captured data through a microcontroller. However their life span is limited and designers of wearables will have to find new and improved solutions to acquire the needed energy, either making it long lasting or easy to recharge on the move. At the same time the energy source must become light and discreet, which currently is the heaviest part of wearables.

The need for alternative sources of power is rising as the demand for greater design freedom in creating light, flexible and reliable wearable e-textile is increasing. Researchers see a potential in an alternative source of power based on the miniaturization of fuel cell technology. The way fuel cells generate electrical power is similar to batteries, as they convert the chemical energy of a given type of fuel (e.g. hydrogen and oxygen) into electrical energy. They have longer lives than batteries of similar size since oxygen does not need to be stored, only hydrogen in metal hydrides (Larminie & Dicks, 2003). Before 2010 Toshiba is planning to launch the first commercial direct methanol fuel cell-based (DMFC) batteries for cell phones and laptops.

In the beginning of 2009 researchers from the University of Illinois claimed they have developed the smallest working fuel cell, with dimensions 3 mm x 3 mm x 1 mm and it is made from four layers: a water reservoir, a thin membrane, a chamber of metal hydride, and an assembly of electrodes (Heine, 2009). Scientists claim that with the capacity of 0.7 volts and a 0.1 milliamp current for about 30 hours the mini battery can be used to run simple electronics. Researches see a great potential in fuel cell technology as it is considered to be a clean, efficient and silent technology, nevertheless the main hurdles preventing commercial introduction is high cost, lack of durability, high system complexity and lack of fuel infrastructure (Bruijn, 2005).

Another interesting alternative energy source for intelligent clothing is to harvest the kinetic energy from the human movement or the fluctuations in body temperature. Even though this energy is very minimal to drive wearable technology and can only be measured in microwatts, it is still a research field that attracts attention. Some research has been done in piezoelectric materials, which creates charge when mechanically stressed, thus inserting them on shoes, walking power can be harnessed (Tao, 2005).

Other forms of power supply are utilizing photovoltaic cells which are gathering the energy of the sun, allowing a sustainable approach to wearable technology. There are many examples of products that are incorporating solar panels onto the surface of wearable e-textiles, using thin film printed on flexible surfaces such as plastics; however the efficiency of this alternative energy source still needs to be improved.

Responsive Materials

Responsive materials represent a new generation of fibers, fabrics and articles, which are able to react in a predetermined way when exposed to stimuli, such as mechanical, electrical, chemical, thermal, magnetic and optical. They are reactive and dynamic and they have the ability to change color, shape and size in response to their environment. For many years researchers have devoted their work in developing responsive materials such as shape memory materials, chromic materials, micro and nanomaterial and piezoelectric materials.

By constantly improving and incorporating responsive materials in the development of light and flexible electronic components, conductive and semi-conductive materials, such as conductive polymers, conductive threads, yarns, coatings and inks, are receiving widespread attention. They are less dynamic then smart textiles but equally important in realizing fashionable, desirable, lightweight, soft and wireless computational textiles.

The following section gives an overview of conductive and responsive materials that are currently most used in wearable computational textiles.

Conductive fabrics and textiles are plated or woven with metallic elements such as silver, nickel, tin, copper, and aluminum. There are many different fabrics with various textures, looks and conductivity and few samples are illustrated in Figure 4 (left), those are: electronylon, electronylon nickel, clearmesh, softmesh, electrolycra and steelcloth. All these textiles show amazing electrical properties, with low surface resistance15, which can be used for making flexible and soft electrical circuits within garments or other products, pressure and position-sensing systems. They are lightweight, flexible, durable, soft and washable (some) and can be sewn like traditional textiles, which makes them a great replacement for wires in computational garments.

image

Figure 4 : conductive fabrics (left) and Different types of conductive threads (Middle and right)

Conductive threads and yarns have a similar purpose to wires and that is to create conductive paths from one point to another. However, unlike wires they are flexible and can be sewn, woven or embroidered onto textile, allowing for soft circuits to be created. They contain metallic elements such as stainless steel or silver, with nylon or polyester as base fiber. Commercially available conductive threads usually vary in the resistance and the thickness of the thread. Figure 5 (middle and right) illustrates few commercially available threads. Since they are conductive when working with them, one has to take all the precautions as when using uncoated electric wire or a metallic surface without insulation. Conductive threads and yarns offer alternative ways of connecting electronics on soft and flexible textiles medium as well offering traditional textile manufacturing techniques for creating computational garments.

Conductive coatings are used to convert traditional textiles into electrically conductive materials. The coatings can be applied to different types of traditional fibers, yarns and fabrics, without changing their flexibility, density and handling.

Conductive ink is an ink that conducts electricity, providing new ways of printing or drawing circuits. This special ink can be applied to textile and other substrates. Since wearable e–textiles require great flexibility, conductive inks are become more interesting for designers and developers in this area. Conductive inks contain powdered metals such as carbon, copper or silver mixed with traditional inks.

Shape memory alloys (SMA or muscle wire) are composed of two or more metals usually nickel and titanium, combination also known as Nitinol. These wires, usually of very small diameter, have the capacity to actuate when heated and to return to their original shape when cooled. Their capacity to flex or contract is up to 5% and it is a result of dynamic changes in their internal structure generated by an electric current. Some SMA wires can be “programmed” (heated at a transition temperature) into a particular shape for ex. zigzag or coiled. They can remember the form, to which they return when cooled. SMAs are used for triggering movement, have been woven in textiles or can make fabrics shrink or curl in wearable e-textiles applications. Long before SMAs were introduced to wearable e-textile projects, they have been used in many different areas, like electronics, robotics, medicine, automotive industry and appliances. SMAs are more and more becoming an interesting material for designers working on interdisciplinary projects across the fields of computation, technology, science, design and art. They explore how new ways of combining SMAs with computation can aid the design of responsive garments, objects and spaces and provide more meaningful interfaces.

Piezoelectric materials have the ability to generate electrical charge when exposed to mechanical stress (sound, vibration, force or motion). Piezoelectric materials exhibit reversible effect because they can produce electrical charge when subjected to stress and also they can generate stress when an electrical field is applied. Therefore the materials can be used both as sensors and actuators. Piezoelectric materials can serve as excellent environmental sensors, but the number of interesting applications in wearable e-textiles is even greater if they are coupled with other sensors, for ex. solar cells where they can be used to convert light to sound, motion or vibration.

Chromic materials are those that radiate, erase or just change the color based on the induction caused by external stimuli. They are also known as non- emissive “active materials” (Berzowska & Bromley, Soft computation through conductive materials , 2007). The classification of chromic materials depends on the stimuli affecting them. Some of the most know are photochromic and thermochromic materials. Most of the color changing phenomena (photochromism, thermochromism, electrochromism, piezochromism etc.) are reversible.

Photochromic (inks and dyes) are materials that react to light as an external stimulus. They are typically available in powdered crystals of ultraviolet (UV) sensitive pigments that need to be dissolved in an ink for application. Once the material is exposed to sunlight, blacklight or other UV source it will change from clear to colored state. When the UV source is removed they revert to their original state. They can be applied on various media, including textile, paper, plastic, wood and glass and can be used to create dynamic patterns that change in accordance to light variations in their surroundings.

Thermochromic inks are heat sensitive materials. They are made from various compounds that need to dissolve in the appropriate ink type for application. When exposed to a specific temperature they change from one color to another of from color to translucent. Thermochromic inks can be classified to three types, low – react to cold, body – react to body heat, touch and breath and high – react to hot liquids and air. They have the ability to infinitely shift color and with that create dynamic patterns on various substrates, including textiles.

Nanomaterials and microfibers have been the subject of enormous interest, over the past decades. They are materials fabricated on a molecular level. The technology is aimed at manipulating the structure of materials on atomic, molecular and nano16 level in a precise and controlled manner to create products or byproducts with specially engineered characteristics. Scientists use the prefix nano to denote a factor of 10-9 or one-billionth. One nanometer is one-billionth meter which is about 100,000 times smaller than the diameter of a single human hair (Qian & Hinestroza, 2004).

Many believe that the future development of many areas of our lives lie in nanotechnology, which fundamentals are based on the fact that properties of substances can change when their size is reduces to the nanometer range. The technology will be used in fabricating nanomachies, nanelectronics and other nanodevices to improve existing products and to create many new ones. Nanotechnology will also

have a great impact on textiles, being able to transform the molecular structure of the fibers and create fabrics that offer unsurpassed performance and comfort. The technology is likely to revolutionize wearable e-textiles, by not only developing very small and flexible electronic devices embedded in textile substrates, but it will go even further, ultimately having the electronic devices and system becoming the fabric itself. Researchers have already started to develop transistors in yarn form and to make conductive, carbon nanotube.

Refrance : E-textiles: The intersection of computation and traditional textiles (Interactive Sample Book by Marija Andonovska)

Ultrasonic Technology in Nonwoven and Textile Industry


Flexible technology for a flexible market

Today’s textile and nonwoven market is so complex that fields of application, production techniques and technologies for further processing as well as the variety of new products are difficult to grasp, even for specialists.The variety of new composite materials of fleece, paper, films and fabric as well as the numerous possibilities in terms of combinations have one requirement in common: a safe and reliable process.

Ultrasonics is also the method of choice for these materials, for example for parting fabrics so that there is no thickening of the material along the cut edges.

No consumables such as glue, staples or sewing thread are needed. The fabric remains intact, because no external thermal energy is directed into the fleece. Position, shape and displacement of the welding points can even support the desired properties of the composite.

Textiles is thus a field where ultrasonic technology can prove its uniqueness.

The Functioning Principle of Ultrasonic Welding

image_thumb.png

Low frequency mains voltage is transformed into high frequency electrical energy. A converter connected in line converts these electrical oscillations into mechanical vibrations. This is done using a piezoelectric transducer having an efficiency above 95 %.

The mechanical vibrations are transferred to a transformer element coupied to the converter, the so-called booster. This booster optimises the amplitude for the horn.

The horn is individually manufactured for each application and transfers the ultrasonic energy to the material to be processed. To build up a mechanical clamping force, a so-called anvil is required enabling the energy to effect melting on account of physical processes (internal and external absorption).

The Optimum Process for any Application

Cycle-controlled process

image

The actuator applies a defined pressure onto the anvil and hence onto the part to be welded between the two components. Usually, the ultrasonic irnpulse applied  simultaneously is time-controlled. Using the weld depth or the amount of energy applied as criteria for deactivation is also possible.

Main fields of application for cyclecontrolled welding:

  • Overlapping welding of belts and tapes
  • Linear welding of fabric and nonwoven
  • Welding textile materials with thermoplastic contents
  • Joining the end of a material strip to the start of a roll to prevent costintensive drawing in of material into the production equipment.

Seal and cut edges can also be manufactured to excellent quality. This only requires a special design of horn and anvil which is important for the following particular applications:

  • Cut belt strips to length and/or punching
  • Parting of edge binding for blankets
  • Manufacturing buttonholes and eyes applying a certain structure to the rim in order to leave the impression of a sewn edge
  • Parting colour ribbons in bureau machine industry

Continuous Process

Two or more overlapping material strips are fed between horn and anvil which, if required, is rotating. Again, different systern combinations are possible:

Fixed Horn/Rotating Anvil

image

This is the most commonly applied combination. Material strips (e. 9. fleece for use in agriculture) are joined at very high speeds using special profile wheels. Using profile wheels, sandwich structures can be generated. Combinations of different materials such as paper, films and textiles are particularly interesting applications. This combination can also be used for cutting processes. This usually involves cutting without sealing or with only slight edge sealling. The extension of the service life as well as the reduction of the cutting force and hence an increased cutting speed are strong arguments for the application of ultrasonic technology. Non-thermoplastic materials can also be cut. In this case ultrasonic energy supports breaking of the materials. Maximum precision is of course a prerequisite in such applications.

Rotating Horn/Rotating Anvil

image

In this combination horn and anvil serve both to weld and to transport the welded product. In most cases both horn and anvil are driven synchronously. As in this system only a limited amplitude can be generated. This method is usually used for thin materials having a low mass per unit area.

Fixed HornlFixed Anvil

image

This combination is usually used for cutting/ parting applications with simultancous sealing. However, it can also be used for continuous welding of paper, films, or textiles.

 

 

 

Refrance: BRANSON BROUCHER