An Overview of E- Textiles || Manufacturing || Applications

An Overview of E-textiles
Sayak Nandi
Government College of Engineering and Textile Technology, Serampore, West Bengal, India.

A. Introduction

Clothing is one of our 3 basis needs. They not only protect us, but also have an aesthetic appeal and also are culturally important. However in recent years with the advancement of technologies, textile material is not confined to clothing anymore. With the introduction of smart textile the textile materials have turned to be more active where it can sense and react to environmental conditions or stimuli from, for example, mechanical, thermal, chemical, electrical, or magnetic sources [1].

The fundamental components in any smart textile are sensors and actuators. Interconnections, power supply and control units are also needed to complete the system. These components must all be integrated into textiles while still retaining the usual tactile flexible and comfortable properties which one expects from a textile [2]. For this the imperative item is electricity conducting textile materials for interconnection of different electrical or electronic components. 

Metals like Copper, Silver, Aluminum, etc. are known to be electricity conductors, since they have free electron(s) which helps them in conducting electricity. Natural textile material inherently doesn’t conduct electricity since they are animal body hairs or cellulosic materials and doesn’t contain free electrons. Even majority of synthetic and regenerated fibres are non-conductors and hence used for resistive and capacitive applications. Many synthetic fibres of resistivity range 105W/cm2 are used for electromagnetic shielding applications [3], capacitive [4] and insulating applications. Textile fibres are however hydrophobic and its electrical properties changes with RH%, amount of moisture absorbed (Shown in Fig 1.), and temperature [5]. In spite of this the electrical properties even at favorable conditions are not suitable enough to be utilized for electricity conducting applications in e-textile hence metals are incorporated within the textile materials by various processes to obtain variety of applications in e-textiles.

Fig. 1: Log conductance (C, Siemen) vs. Regain (%) for (a) cellulosic material [6], (b) Wool and silk [7]


B. Methods Used for Production of Conductive Textile

The production of conductive materials can be traced way back. However the literature shows patents of conductive yarns production from early 19th Century [8].

B.1. Underwood’s technique of metal ribbon formation [8]

It is the process most commonly used in industry. Here metals like silver, gold, copper, aluminium is extruded and deposited onto a cold moving substrate to ensure fast cooling shown in Fig. 2(a).  With this technique very fine yarns suitable for knitting and spinning can be produced.

B.2. Conductive core spinning [8]

In this technique a filament is twisted around an existing yarn. The metallic filament is fed in a comparatively higher tension between two strands of fibres. Being in higher tension, when relaxed it twists with the two stands of yarn, and a pair of frictional rollers moving in same direction helps in creating a core-sheath structure(Fig. 2(b)). This technique is used for production of coarse count yarns.

B.3. Commingled warp spinning [8]

This is a core spinning yarn (Fig 2(c)), where the core is mainly drafted sliver with false twist, and conductive yarn wrapped helically over it giving the yarn stability. The yarns produced has high strength, good aberasive properties, wash wear and perspiration resistant properties. However these yarns are fragile and brittle and cannot conduct high electricity.

B.4. Laminated/Coated conductive yarns [8]

In this spinning the substrate is unwound from a spool and is passed through a tank containing liquid metals. The dipping is precisely controlled to ensure even disposition of metal on the surface. The dipped substrate is then heated in a heating chamber followed by winding. The solution contains molten metals or carbon conductive halogens (Fig. 2(d)).

B.5. Bi component and multicomponent spinning [8]

In this technique thermoplastics are used where it is melt spun with two or more component of conductive molten metals. During extrusion the type of metal, shape of extruder and cooling effect determines the final yarn shown in fig 2(e). Generally carbon nanotubes and graphene is used for molten conductive part.

These types of yarns are very robust, and their characteristic functions, such as stress-strain behavior, low shrinkage, high modulus, good electrical conductivity, toughness, and solvent resistance, can be tailored. Knittable yarns suitable for strain sensing and other smart textile applications can best be produced via this technology. However, yarns produced using this technology is not yet available in commercial markets.

B.6. Extrusion coating spinning [8]

In this method a sandwitch is obtained where the conductive metal sheet is in the middle and on both the side fibre sheets and wound onto the bobbin. The laminated sheet is cut are then slit into filaments and spun into yarns (Fig. 2(f)).

Fig. 2: Methods for production (a) Underwood’s technique, (b) Core spinning, (c) Commingled spinning, (d) Dip Coating, (e) Filament Matrixes, (f) Extrusion coating method


B.7. Hybrid Ring spinning [9]

This a new technology, where the conductive yarns (Carbon black and ethanol solution) is sprinkeled onto the sliver or roveing in drafting zone for even diposition of the conductive material. With this technique conductive yarn can be produced with the help of ring spinning system with proper optimization done in the literature [9].

B.8. Other conductive yarn producing methods

Several methods have been proposed, patented and developed in the recent century for this technology. Blending in different contentrations of conductive yarns in fibre stage is one such alternative but it is rarely used due to uneven electrical conductance that might occur due to uneven blending [8]. Plasma coating of conductive metals on yarn is another method used to obtain highly conductive yarns [10]. Different coating metals and composits like polypyrrole (PPy), polyaniline, and polythiophene have been used for good conductance, environmental stability, non-toxicity, etc. [11]. Polydoapamine is another self-polymerized substance which has been extensively used for coating applications in several literatures [11, 12].  Certain Carbon halogens like graphene, carbon fibres, carbon nanotubes, have been used in several literatures as a conductive yarns for superconductive, super capacitive applications [8, 13]. These carbon halogens have also been doped onto fibres, fabrics and yarns surfaces for higher conductance [14]. Silver and nano spun (generally electrospun) Silver is also extensively recently for preparation of conducting yarns, as microelectrodes, also to achieve anti-microbial effects on textile [8].  Not only coated fibres, genetically modified silk that conducts electricity has also been produced. Silkworm was fed graphene and carbon nanotubes sprinkled on mulberry leaves, and the genetically modified silk obtained was seen to be highly electricity conductive [15], similarly genetical modifications of several other natural fibres are been researched to obtain naturally conductive yarns.

B.9. Other conductive textile producing methods

Several methods have been adapted for preparation of conductive textile in fabric, knitted and braided stages, coating and printing of textile with conductive inks [16] containing powdered metals are two of the most commonly used methods. Coating techniques including screen printing, ink-jet printing, electrodeposition, electroless plating, sputtering of thin films, vapor deposition and thermoset coatings have been used so far [17]. Doping of metals and carbon halogens onto fabric surfaces is also done [14]. It was seen it is most efficient and easy and cost effective to use conductive yarns than directly on fabric (Table 1). However in production of patterned electrodes conductive inks are preferred over yarns [18].

Table 1: Qualitative comparison of E-textile fabrication attributes [18]

E-textile Manufacturing Technique

Machinery Cost

Material Cost

Process Complexity

Resistance to wear

Embroidery

High

Low

High

High

Sewing

Low

Low

Low

High

Weaving

Low

High

High

High

Non-woven

Low

Low

Low

Low

Knitting

Low

High

High

Low

Spinning

Low

Low

Low

Low

Breading

Low

Low

Low

High

Coating

High

Low

Low

Low

Printing

High

High

Low

Low

 C. Applications of Conductive Materials in E-Textile

According to manner of reaction, smart textile material can be divided into passive smart, active smart and very smart material. Passive smart materials can only sense the environmental conditions or stimuli; active smart materials will sense and react to the conditions or stimuli; very smart materials can sense, react and adapt themselves accordingly. An even higher level of intelligence can be achieved from those intelligent materials and structures capable of responding or activated to perform a function in a manual or pre-programmed manner [19]. Of all these smart materials the key ingredient is a conductive textile material and depending on the application the type of sensors, actuators, and the conductive material varies as shown.

C.1. Project Jacquard

Project Jacquard initially undertaken in 2016 by Google Inc. and Levi’s, is one of the Google’s Advanced Technology Projects. In this project conductive yarns are prepared and woven to produce interactive textile, that enables multitouch, navigation, communication and interaction with mobile phones and tablets using gesturing and touch sensing on textile surfaces.The project initially used on Levi’s Tucker Jackets is designed in such a way that it can be produced at a scale by standard textile manufacturing processes and can be dyed with any colour, ensuring comfort, breathability of the parent textile material remains intact. Depending on the design the sensing area can customised to be identifiable or invisible. The full manufacturing process of project jacquard is shown in Fig. 3. This technology can be used in clothing, furnitures, accessories, bags, toys, carpets, interior, automotive etc.[20]

Fig. 3: Project Jacquard manufacturing process 

In 2020 this technology was used by Adidas, to produce Adidas GMR for EA SPORTS FIFA Mobile Games to give a interactive physical footballing and digital gameing. It has also been used by Saint Laurent in producing their luxuary range of backpacks Cit-e Backpack, that can control music, drop pins on go, take pictures with simple gesture [21]

C.2. Military Applications

Georgia tech wearable motherboard(GTMW), initially developed in 1996 by US Defence Advanced Project Research Agency is a wearable functional clothing that alerts the medical triage unit when a soldier is shot or is in need of medical attention. The particular apparel is designed to be light weight, easy to wear and remove, breathable and durable for 120 combat days that has the ability to withstand repeated flexure and aberation. The GTMW contains sensors connected with a PSM( Personal Status Monitor) which senses and informs the medical unit about the health condition of the particular soldier. This technology though has been designed for soldiers however can also be used in various sectors [19] , Table 2.

Table 2: Potential Application of GTMW [19]

Segment

Application Type

Target Customer Base

Military

Combat Casualty Care

Soldiers and support personnel in battlefield

 

Civilian

Medical monitoring Patients

Surgical recovery, psychiatric care

Senior citizens: geriatric care, nursing homes

Infants: SIDS prevention

Teaching hospitals and medical research institutions

Sports/performance monitoring

 

Athletes, individuals Scuba diving, mountaineering, hiking

Space

Space Experiments

Astronauts

Specialized

Hazardous Applications

Mining, Mass Transportation

Public Safety

Fire Fighting/ Law enforcement

Firefighters police

Universal

Wearable mobile infrastructure

All Information Processing Applications

For the army e-textile have also been used for locating soldiers, communication purposes, monitoring environmental conditions, for detecting infrared signals, decoding different audios signals of enemies, for surveillance purposes infrared camera, laser range finder has also been proposed. Even in certain camouflage applications e-textiles has been used [22]

C.3. Medical Applications

Most of the Existing wearable technologies are based on physical sensors and used for assessing different body parameters and for diagonistics applications. The major monitoring specifications are given in Table 3.

Table 3: Physiological signals that may be measured using textile-based sensors [23, 24]

Physiological measurement

Textile-integrated sensors

Signal source

Typical sensor placement

Breathing patterns

Piezoresistive stretch sensors, inductive plethysmography, impedance plethysmography, optical fibres

Expansion and contraction of ribcage during breathing

Thoracic- abdominal region

Heart activity

Woven/Knitted electrodes

Electrical activity of heart

Thoracic region

Muscle activity

Woven/Knitted electrodes

Electrical activity of muscles

Skin surface overlying muscle

Blood oxygen saturation

Optical sensing components, plastic optical fibres

Light absorption of hemoglobin in blood

Region with good blood perfusion

Blood pressure

Features of the photoplethysmography signal

Arterial pressure pulsations

Finger, wrist and earlobe

Body movement posture

Piezoresistive strain/ pressure sensors, accelerometers, gyroscopes, optical fibre sensors

Body kinematics

Dependent on motion to be analyzed

Electro dermal activity

Woven electrodes

Skin electric conductivity

Fingertips

Composition of body fluids

Electrochemical sensors, colorimetric pH fabric

Composition of sweat, saliva, urine

Fluidic sampling system necessary

Body Temperature

Thin film flexible sensors, thermocouples, RTDs

Heat generated from the body

Depending on the part of body

Adaptable textile antennas, smart clothing, smart bras have also been proposed in the literature for detection of breast cancer, where an electric current goes into the body detecting the different electromagnetic conduction between tissues thus differentiating tumor tissue from a healthy one. [25,26].

Not only sensing medical textile with drug releasing applications have also been using sensors [27], smart wound detection by textile garment with sensing and localization application has also been designed using conductive textiles [28].

C.4. Fashion and Accessories

The recent developments and commercialization of wearable computer technologies have brought about several changes in the fashion industries. The textile and fashion has not only embressed this change, but also changed along with it. Major main stream fashion accessories like wrist watches, bracelets, nechlaces had digital features addition [29]. Even certain fashion designers have used the E-textile in their collections [30].

C.4.1. Wearable Solar

Pauline van Dongen and Christiaan Holland in 2013 initially designed the Wearable Solar collection. This is a fusion of technology and fashion, where technology is used to make light weight wired garments that enable the wearer to charge up smartphone upto 50% if the wearer stands in Sun for 1 hour. Fig 4(a)

C.4.2. Cute Circuit

Internationally known fashion house Cute Circuit have been a global leader in implementing technology into wearable technology, since 2004. They have had many ground breaking fashion ideas to fashion by using microelectronics for value addition to fabric; they even have a fabulous international celebrity fan base such as Nicole Scherzinger and Katy Perry. Their products are Oeko Tex certified, i.e. completely safe for the use of common people. Fig 4(b)

C.4.3. Rainbow Winters

Rainbow Winters is a clothing lines designed by Amy Winters. They are a range of interactive clothing which reacts to different stimuli. Majority of the dresses are made of holographic leather, which illuminated when the surrounding sounds gets louder; Winters describes it as “visual music”.  Even her bathing suit line reacts to light, where purple dots appears when exposed to sun With the advancement of smart and interactive textile, the fashion trends have changed. Similarly fashion designers have also adapted to the technology and they are bringing change in their business model and designs [30, 31]. Fig 4(c)

Fig 4: Different Fashion and smart textile fusions, (a) Wearable Solar garment, (b) Cute Circuit sound shirt, (c) Rainbow Winters garment


C.5. Other Applications

From the use of classical electronic devices like wires, LEDs, batteries into textile materials it has evolved considerably. However the application of e-textile is still limited due to the fact the production of these has not yet become main stream. Apart from medical, fashion, millitary applications production of green energy is another aspect. Production of solar energy (Solar Textiles) from textile has been used for  decades. Production of energy from human limb movement [32] has opened a new direction in green energy production.

Fig. 5: Schematic illustration of Microbial Fuel Cell operating Principle [33]

Microbial fuel cells which generated energy from waste water or any biodegradable compounds is a new green energy that has been researched in recent years even its integration into textiles has been done [33].  Its operation is shown in Fig. 5 . Garments, skin mountable batteries has been designed which can generate voltage of 0.5V, 200μA/cm2 cuttent density depending on the type of bacteria from human sweat [34]. Similar green energy from different sources is being  intensively researched and e-textile has opened a new route for this developments.

D. Demands in Present and Future Applications

A market survey conducted by Grand View Research shows the Market size of smart textiles for e-textiles is expected to reach $5.55 Billion by 2025, with a CAGR of 30.4% [35]. It has been revealed the consumption of Passive, Active and Very smart e-textile has significantly increased from 2011-2015 to 2015-2020 and is expected to rise in the period 2020-2025. One of the major barriers is naturally obtained textile materials don’t conduct electricity as a result the production cost of these materials are significantly high shown in Fig. 6.  Hence compared to any textile integrated material, normal metal and alloys provide far better conductance in a lesser cost as a result it is a shortcoming. Carbon fibres in recent times have gained significance and might be very useful in the future.

In current pandemic situation where thermal scanning is an important aspect, temperature sensing integrated textile can be very useful for detecting fever of any individual.

Fig. 6: Electrical resistivity Vs. Cost of the e-textile materials [25]


E. Conclusion

The advancement of smart textile has seen a growth in consumption of e-textiles. With new applications now e-textiles is not only limited to high end fashion, it has found its ways into medical, military, automobiles, green energy production fields. With a current growing market and with the change in fashion trends, the day is not very far when the e-textiles will find its way into wardrobe of common people.

F. References

1.   Axisa, F., et al.  (2005). Flexible Technologies and Smart Clothing for Citizen Medicine, Home Healthcare and Disease Prevention. IEEE Transactions on Information Technology in Biomedicine. 9(3), 325-336.

2.   Rebouillat, S. & Lyons, M.E.G. (2011). Measuring the Electrical Conductivity of Single Fibres. International Journal of Electrochemical Science. 6, 5731 – 5740.

3.   Chen, H.C., et al. (2007). Comparison of electromagnetic shielding effectiveness properties of diverse conductive textiles via various measurement techniques. Journal of Materials Processing Technology. 192-193, s. 549-554.

4.   Mukherjee, P.K. (2019). Dielectric properties in textile materials: a theoretical study. The Journal of The Textile Institute. Vol. 110(2), 211-214.

5.   Baxter, S. (1943). Electrical Conduction of Textiles. Transaction of Faradays Society. Vol. 39, 207-214.

6.   Christie, J.H. & Woodhead, I.M. (2002). A New Model of DC Conductivity of Hygroscopic Solids: Part I: Cellulosic Materials. Textile Research Journal. 273-278

7.   Christie, J.H., et al. (2002). A New Model of DC Conductivity of Hygroscopic Solids: Part II: Wool and Silk. Textile Research Journal. 303-308

8.   Raji, R.K., et al. (2017). Electrical Conductivity in Textile Fibres and Yarns-Review. AATCC Journal of Research. Vol. 4(3), 8-21

9.   Kayabasi, G., et al. (2020). A novel yarn spinning method for fabricating conductive and nanofiber-coated hybrid yarns. Journal of Textile Institute. 0(0), 1-24

10.  Uddin, A.J. (2010). Coating for technical textile yarns. Researchgate,140-184

11.    Gokarnesha, N. & Srivatsav, G. N. (2018). Some Significant Trends in Conductive Textiles. Trends in Textile & Fashion Design 2(3), 179-186. LTTFD.

12.    Ball, V. (2018). Polydopamine Nanomaterials: Recent Advances in Synthesis Methods and Applications. Frontiers in Bioengineering and Biotechnology. 6:109

13.    Ferrier, M. et al. (2009). Superconducting properties of carbon nanotubes. Comptes Rendus Physique. Vol. 10(4), 252-267

14.    Li., L. et al. (2016). Surface micro-dissolution process for embedding carbon nanotubes on cotton fabric as a conductive textile. Cellulose, Vol. 24, 1121-1128

15.    Wang, Q. et al. (2016). Feeding Single-Walled Carbon Nanotubes or Graphene to Silkworms for reinforced Silk Fibres. Nano Letters (ACS). 16, 6695-6700

16.    Anwar, S. (2019). Manufacturing of Electronic Textile. Fibre2Fashion (Article).

17.    Castano, L.M. & Flatau, A.B. (2014). Smart fabric sensors and e-textile technologies: a review. Smart Materials and Structures. Vol.- 23, 1-27

18.  Gonçalves, C.et al. (2018). Wearable E-textile Technologies: A Review on Sensors, Actuators and Control Elements. Inventions. Vol. 3(14), 1-13

19.  Tao, X. (Editor). (2001). Smart Fibres, Fabrics and Clothing (Book). The Textile Institute, Woodhead Publishing Limited

20.  Poupyrev, I. et al. (2016). Project Jacquard: Interactive Digital textiles at Scale. TED Conference, San Jose, CA, USA

21.  Jacquard by Google. https://atap.google.com/jacquard/

22.  Nayak, R. et al. (2015). Electronic textiles for military personnel. Smart Fabrics and Wearable Technology, page- 239-256

23.  Coyle, S. et al. (2016). Medical applications of smart textiles. Advancement in Smart Medical Textiles (Book), Woodhead Publishing, page – 215-237

24.  Lugoda, P. et al. (2020). Flexible Temperature Sensor Integration into E-Textiles Using Different Industrial Yarns Fabrication Processes. Sensors, Vol.- 20(1), 73

25.  Mogahzy, Y.E. (2009). Integrating the design and manufacture of textile products (Book). The Textile Institute, Woodhead Publishing Limited

26.  Srinivasan, D. Gopalakrishnan, M. (2019). Brest Cancer Detection Using Adaptable Textile Antenna Design. Journal of Medical Science. 43,177

27.  Qin, Y. (2016). Medical textile materials with drug-releasing properties. Medical Textile Materials (Book). Page- 175-189

28.  Holland, S.A. (2013). Conductive Textiles and their use in combat wound detection, sensing and localization applications. (MSC Thesis Paper) University of Tennessee, Knoxville

29.  Han, A. et al. (2020). Towards new fashion design education: learning virtual prototype using E-textiles. International Journal of Technical Design Education.

30.  Saad, A. (2015). 5 Designers Using Smart Textiles in Intelligent Ways. SynZenBe Magazine.

31.  Agarwal, R. (2019). Wearable Technology: Transforming The Fashion Industry. E2logy (Blog). https://e2logy.com/wearable-technology-transforming-the-fashion-industry/

32.  Li. K, et al. (2018). Wearable energy harvesters generating electricity from low-frequency human limb movement. Microsystems & Nanoengineering (Nature). 4,24.

33.  Pang, S. et al. (2018).  Flexible and stretchable microbial fuel cells with modified conductive and hydrophilic textile. Biosensors and Bioelectronics. 100, 504-511

34.  Mohammadifar, M. et al. (2020). Biopower-on-skin: Electricity generation from sweat-eating bacteria for self-powered E-Skins. Nano Energy. 75, pp-1-8

Grand View Research. (2019). Smart textile Market Size Worth $5.55 Billion by 2025| CAGR: 30.4%


Post a Comment

4 Comments