Study of the properties of electrically conductive materials/composites for smart textile product applications
Abstract
An electrically conductive textile conducts an electrical current or supplies an electric field to a device. They are usually part of a smart textile system, a textile-based system that exhibits a reaction either to changes in its surroundings/environment or to an external signal/input. Smart textile systems are also known as smart or intelligent textile/garment. Wearing apparel manufacturing companies are proposing smart garments manufactured from smart textiles for outdoor wear, sportswear, lifestyle, and urban life but conductive textiles have not yet reached mass-market consumers as initially forecasted; the endconsumer is not confident to invest in a costly garment with yet unclear cleaning requirements and a potential loss of functional properties after domestic laundry. This thesis studies the influence of domestic washing and abrasion on conductive fabrics and the effects on their surface electric resistance. In addition, it will also be observed the surface change after the abrasion in order to link any physical surface modification with the experimental findings. The specimens to be analysed are conductive warp knitted structure and a non-woven conductive structure combined with a conventional knitted structure forming a 2D conductive composite by lamination; a conductive TPU film laminated with a conventional textile knitted structure and an electronic circuit printed conductive ink and transferred by heat press onto a conventional knit structure; all six 2D conductive specimens have the same conventional ground fabric: a warp knit structure of polyamide and elastane. The conductive 2D materials will be exposed to washing and abrasion tests and their linear surface resistance will be measured at the initial stage of the experiment and compared with their conductive properties during and after the completion of the experimental tests. The work aims to contribute to a better understanding of the effects of domestic laundry and abrasion on the surface resistance of conductive textiles
Full text
STUDY OF THE PROPERTIES OF ELECTRICALLY CONDUCTIVE MATERIALS/COMPOSITES FOR SMART Document: Report Author: Maria Pilar Garcia Bolaño Director /Co Elina Emilia Ilén / Mònica Degree: Master in Design and Advance Textile Technologies Examination session: Spring, 2022 STUDY OF THE PROPERTIES OF ELECTRICALLY CONDUCTIVE MATERIALS/COMPOSITES FOR SMART Document: Report Author: Maria Pilar Garcia Bolaño Director /Co Elina Emilia Ilén / Mònica Degree: Master in Design and Advance Textile Technologies Examination session: Spring, 2022 STUDY OF THE PROPERTIES OF ELECTRICALLY CONDUCTIVE MATERIALS/COMPOSITES FOR SMART TEXTILE Document: Maria Pilar Garcia Bolaño Director /Co - director: Elina Emilia Ilén / Ardanuy Raso Master in Design and Advance Textile Technologies Examination session: Spring, 2022 STUDY OF THE PROPERTIES OF ELECTRICALLY CONDUCTIVE MATERIALS/COMPOSITES FOR TEXTILE PRODUCT APPLICATIONS Maria Pilar Garcia Bolaño director: Elina Emilia Ilén / Ardanuy Raso Master in Design and Advance Textile Examination session: STUDY OF THE PROPERTIES OF ELECTRICALLY CONDUCTIVE MATERIALS/COMPOSITES FOR PRODUCT APPLICATIONS Maria Pilar Garcia Bolaño Ardanuy Raso Master in Design and Advance Textile STUDY OF THE PROPERTIES OF ELECTRICALLY CONDUCTIVE MATERIALS/COMPOSITES FOR PRODUCT APPLICATIONS Master in Design and Advance Textile STUDY OF THE PROPERTIES OF ELECTRICALLY CONDUCTIVE MATERIALS/COMPOSITES FOR PRODUCT APPLICATIONS Master in Design and Advance Textile PRODUCT APPLICATIONS PRODUCT APPLICATIONS MA ST ER FIN AL TH ESI S MA ST ER FIN AL TH ESI
2 Abstract An electrically conductive textile conducts an electrical current or supplies an electric field to a device. They are usually part of a smart textile system, a textile-based system that exhibits a reaction either to changes in its surroundings/environment or to an external signal/input. Smart textile systems are also known as smart or intelligent textile/garment. Wearing apparel manufacturing companies are proposing smart garments manufactured from smart textiles for outdoor wear, sportswear, lifestyle, and urban life but conductive textiles have not yet reached mass-market consumers as initially forecasted; the endconsumer is not confident to invest in a costly garment with yet unclear cleaning requirements and a potential loss of functional properties after domestic laundry. This thesis studies the influence of domestic washing and abrasion on conductive fabrics and the effects on their surface electric resistance. In addition, it will also be observed the surface change after the abrasion in order to link any physical surface modification with the experimental findings. The specimens to be analysed are conductive warp knitted structure and a non-woven conductive structure combined with a conventional knitted structure forming a 2D conductive composite by lamination; a conductive TPU film laminated with a conventional textile knitted structure and an electronic circuit printed conductive ink and transferred by heat press onto a conventional knit structure; all six 2D conductive specimens have the same conventional ground fabric: a warp knit structure of polyamide and elastane. The conductive 2D materials will be exposed to washing and abrasion tests and their linear surface resistance will be measured at the initial stage of the experiment and compared with their conductive properties during and after the completion of the experimental tests. The work aims to contribute to a better understanding of the effects of domestic laundry and abrasion on the surface resistance of conductive textiles. Resum Un tèxtil conductor elèctric dirigeix un corrent elèctric o subministra un camp elèctric a un dispositiu. Normalment formen part d'un sistema tèxtil intel·ligent, que exhibeix una reacció als canvis en el seu entorn o a un senyal/entrada externa. Els sistemes tèxtils intel·ligents també es coneixen com a teixits intel·ligents o prendes de roba intel·ligents. Les empreses de fabricació de peces de roba estan proposant peces intel·ligents fabricades a partir de tèxtils intel·ligents per a ús a l'aire lliure, roba esportiva i moda urbana, però els tèxtils conductors encara no han arribat als consumidors de mercat massiu com es preveia inicialment; el consumidor final no té confiança a invertir en una peça costosa amb requisits de neteja encara poc clars i una pèrdua potencial de propietats funcionals després de la bugada domèstica. Aquesta tesi estudiarà la influència del rentat domèstic i l'abrasió en teixits conductors i els efectes en la seva resistència elèctrica superficial. A més, també s'observarà el canvi de textura en superfície després de l'abrasió per enllaçar qualsevol modificació física de la superfície amb els resultats experimentals. Les mostres que s'analitzaran són una estructura conductora de punt per ordit i una estructura conductora de teixit no-teixit, ambdues combinades amb una estructura de punt per ordit convencional formant un compost conductor 2D per laminació; una pel·lícula conductora de TPU laminat amb una estructura de punt per ordit convencional i
3 un circuit electrònic imprès amb tinta conductora i transferit per premsa tèrmica a una estructura de punt per ordit convencional; els sis exemplars conductors 2D tenen el mateix teixit de base convencional i no conductiu: una estructura de punt per ordit feta de poliamida i elastà. Els materials 2D conductors s'exposaran a proves de rentat i abrasió, i la seva resistència lineal a la superfície es mesurarà en l'etapa inicial de l'experiment i es compararà amb les seves propietats de conducció durant i després de la finalització de les proves experimentals. El treball té com a objectiu contribuir a una millor comprensió dels efectes de la bugada domèstica i de l'abrasió, en la resistència superficial dels materials conductius.
4 Table of contents ABSTRACT ................................................................................................................................................ 2 RESUM ..................................................................................................................................................... 2 TABLE OF CONTENTS ................................................................................................................................ 4 LIST OF ABBREVIATIONS / GLOSSARY ....................................................................................................... 7 1. INTRODUCTION................................................................................................................................ 8 1.1 RATIONALE AND MOTIVATION ............................................................................................................... 15 1.2 OBJECTIVES ....................................................................................................................................... 17 1.3 SCOPE OF THE STUDY ........................................................................................................................... 18 1.4 REQUIREMENTS .................................................................................................................................. 19 1.5 STUDY STRUCTURE .............................................................................................................................. 20 2. REVIEW OF THE STATE OF THE ART ................................................................................................. 21 2.1 CONDUCTIVE TEXTILES ......................................................................................................................... 21 2.2 EFFECTS OF DOMESTIC LAUNDRY ON CONDUCTIVE FABRICS. ......................................................................... 23 2.3 EFFECTS OF ABRASION RESISTANCE ON CONDUCTIVE FABRICS. ...................................................................... 24 3. SPECIMEN CHARACTERIZATION AND PREPARATION ....................................................................... 24 3.1 CRITERIA FOR THE SELECTION OF THE CONDUCTIVE AND NON-CONDUCTIVE TEXTILE SUBSTRATES FOR THIS MFT ..... 24 3.2 CHARACTERISATION OF THE SELECTED CONDUCTIVE AND NON-CONDUCTIVE TEXTILE /ELEMENTS ......................... 25 3.3 COMMENTS ON THE SELECTED CONDUCTIVE MATERIALS .............................................................................. 29 3.4 PREPARATION OF THE 2D CONDUCTIVE SPECIMENS .................................................................................... 29 4. METHODOLOGY ............................................................................................................................. 32 4.1 TESTING PROCESS ................................................................................................................................ 32 4.1.1 MODIFICATIONS TO WASHING METHODOLOGY ISO 6330_2021 STANDARD. ................................................. 32 4.1.2 MODIFICATIONS TO SURFACE CONDUCTIVE TEST, AATCC TEST METHOD 76-1995 .......................................... 33 4.2 CONDUCTIVITY AFTER WASHING ............................................................................................................. 33 4.2.1 WASHING PROCEDURE ......................................................................................................................... 33 4.2.2 CONDUCTIVITY MEASUREMENT PROCEDURE ............................................................................................. 34 4.3 CONDUCTIVITY AFTER ABRASION RESISTANCE PROCEDURE ........................................................................... 37 4.4 VISUAL OBSERVATION OF THE SPECIMENS' SURFACE APPEARANCE ................................................................. 40 5. RESULTS AND EVALUATION ............................................................................................................ 41 5.1 EFFECTS OF WASHING CYCLES ON LINEAR SURFACE RESISTANCE ..................................................................... 43 5.2 EFFECTS OF ABRASION ON LINEAR SURFACE RESISTANCE .............................................................................. 48 5.3 EFFECTS OF WASHING CYCLES AND ABRASION ON SPECIMENS' SURFACE APPEARANCE AFTER 20 WASHING CYCLES .. 51 5.3.1 EFFECTS OF WASHING CYCLES ON SPECIMENS' SURFACE APPEARANCE AFTER 20 WASHING CYCLES ....................... 51 5.3.2 EFFECTS OF ABRASION ON SPECIMENS' SURFACE APPEARANCE AFTER 20 WASHING CYCLES AND 1000 CYCLES OF ABRASION ....................................................................................................................................................... 54 6 CONSIDERATION AND DECISION REGARDING ALTERNATIVE SOLUTIONS ......................................... 60 7 DISCUSSION OF THE PROPOSED SOLUTIONS ................................................................................... 64 8 BUDGET SUMMARY ....................................................................................................................... 66 9 ANALYSIS AND ASSESSMENT OF ENVIRONMENTAL AND SOCIAL IMPLICATIONS ............................. 67 10 CONCLUSIONS ................................................................................................................................ 68 11 REFERENCES ................................................................................................................................... 70
5 List of tables TABLE 1.CONDUCTIVE TEXTILE /ELEMENTS TO BE PART OF 2D COMPOSITE AS LAYER 1 ....................................................... 25 TABLE 2.NONCONDUCTIVE TEXTILE TO BE PART OF 2D COMPOSITE AS LAYER 2 ............................................................... 26 TABLE 3.REFERENCES OF THE 2D SPECIMENS ............................................................................................................. 31 TABLE 4.SEQUENCE OF THE CONDUCTIVITY TEST , THE ABRASION TESTS AND MAGNIFIER OBSERVATION TO BE CONDUCTED IN THIS STUDY ....................................................................................................................................................... 32 TABLE 5.WASHING PARAMETERS CONSIDERED FOR THIS STUDY ..................................................................................... 34 TABLE 6.LINEAR SURFACE RESISTANCE AFTER EACH WASHING CYCLE ............................................................................... 41 TABLE 7.LSR VALUES OF 2D SPECIMENS CONDUCTED AT 0 WASHING CYCLE AND AFTER 0,250, 500 AND 1000 ABRASION CYCLES. ................................................................................................................................................................ 42 TABLE 8.LSR VALUES OF 2D SPECIMENS CONDUCTED AT 20 WASHING CYCLE AND AFTER 0,250, 500 AND 1000 ABRASION CYCLES. ...................................................................................................................................................... 43 TABLE 9. LSR DIFFERENCE BETWEEN WASHING CYCLE 0 AND CYCLE 15 AND ITS INCREASE IN PERCENTAGE ............................. 47 TABLE 10.LSR DIFFERENCE BETWEEN 0 AND 1000 ABRASION CYCLES FOR SPECIMENS AFTER WASHING CYCLE 20, AND ITS INCREASE OR DECREASE IN PERCENTAGE ........................................................................................................... 50 TABLE 11.LSR VALUES FOR KNIT 1 SPECIMEN INSIDE AND OUTSIDE THE WRINKLE / PLEAD (20 WASHING CYCLES) ................... 52 TABLE 12.LSR VALUES FOR KNIT 1 AND KNIT 2SPECIMEN INSIDE AND OUTSIDE THE COLOURED AREA (20 WASHING CYCLES) .... 54 TABLE 13.FINAL COST OF THE EXECUTION OF THE PROJECT. .......................................................................................... 66 List of figures FIGURE 1.WEARABLE TECHNOLOGY REVENUES AND SALES AS A FUNCTION OF TIME. SOURCE HTTPS://WWW.IDTECHEX.COM/EN/RESEARCH-REPORT/WEARABLE-TECHNOLOGY-FORECASTS-2021-2031/839 ........... 8 FIGURE 2.WEARABLE TEXTILE. SOURCE: ISLAM, MD RASHEDUL & AFROJ, SHAILA & BEACH, CHRISTOPHER & ISLAM, MOHAMMAD & PARRAMAN, CARINNA & ABDELKADER, AMR & CASSON, ALEX & NOVOSELOV, KOSTYA & KARIM, NAZMUL. (2022). FULLY PRINTED AND MULTIFUNCTIONAL GRAPHENE-BASED WEARAB .............................................. 9 FIGURE 3.WEARABLE TECHNOLOGY FOR SIGNAL MONITORING APPLICATIONS. SOURCE: AHSAN, M.; TEAY, S.H.; SAYEM, A.S.M.; ALBARBAR, A. SMART CLOTHING FRAMEWORK FOR HEALTH MONITORING APPLICATIONS. SIGNALS 2022, 3, 113-145. HTTPS://DOI.ORG/10.3390/SIGNALS3010009. .............................................................................................. 10 FIGURE 4. NADI X YOGA PANTS. SOURCE: HTTPS://WWW.LIFEWIRE.COM/BEST-SMART-CLOTHES-4176104 ........................ 11 FIGURE 5. NADI X CARE INSTRUCTIONS LABEL. SOURCE: HTTPS://WWW.WEARABLEX.COM/PAGES/USER-MANUAL ................. 11 FIGURE 6.NADI X LIFE SPAN. SOURCE: HTTPS://WWW.WEARABLEX.COM/PAGES/USER-MANUAL ........................................ 12 FIGURE 7.FUNDAWEAR® IOS APP. SOURCE: HTTPS://WWW.WEARABLEX.COM/PAGES/FUNDAWEAR .................................. 12 FIGURE 8.SENSORIA® RUNNING SYSTEM. SOURCE: WWW.SENSORIA.COM ...................................................................... 12 FIGURE 9. HEXOSKIN. SOURCE WWW.HEXOSKIN.COM ................................................................................................. 13 FIGURE 10.HEXOSKIN RECOMMENDATIONS ON CARE INSTRUCTIONS. SOURCE: HEXOSKIN.ZENDESK.COM .............................. 14 FIGURE 11.HEXOSKIN HEXOSKIN RECOMMENDATION ON DRYING .................................................................................. 14 FIGURE 12. FORD SAFE CAP "THIS HAT KNOWS WHEN YOU'RE SLEEPING". SOURCE: HTTPS://WWW.WAREABLE.COM/WEARABLETECH/FORD-SAFECAP-TRUCKER-SMART-HAT-1239 ............................................................................................ 14 FIGURE 13.LABELLING LAUNDRY SYMBOLS. SOURCE: HTTPS://WWW.FIBRE2FASHION.COM/INDUSTRY-ARTICLE/8788/YOURGUIDE-TO-GARMENT-LABELING-REQUIREMENTS-FOR-CLOTHING. .......................................................................... 16 FIGURE 14.PROJECT SCHEME, (SOURCE: OWN SOURCE) ............................................................................................... 20 FIGURE 15. ELECTROCARDIOGRAPHY (ECG) SENSOR. SOURCE : HTTPS://WWW.PLUXBIOSIGNALS.COM/PRODUCTS /ELECTROCARDIOGRAPHY-ECG-SENSOR-1 ......................................................................................................... 21 FIGURE 16.TEXTILE-SENSOR SOURCE: HTTPS://MATERIALDISTRICT.COM/MATERIAL/TEXTILE-SENSOR/TEXTILE-SENSOR-PLA10184/ ............................................................................................................................................................ 22 FIGURE 17. SMART TEXTILE SYSTEM. SOURCE : LINA RAMBAUSEK ................................................................................. 22 FIGURE 18.KNIT 1................................................................................................................................................ 27 FIGURE 19. NON-WOVEN ...................................................................................................................................... 27 FIGURE 20.TPU (ON BLACK FLAT SURFACE FOR EASE OF VIEW) ..................................................................................... 27 FIGURE 21.TRANSFER 1 ........................................................................................................................................ 28 FIGURE 22. KNIT 2 ............................................................................................................................................... 28
6 FIGURE 23.NON-CONDUCTIVE FABRIC ...................................................................................................................... 28 FIGURE 24. PLACING CONDUCTIVE TEXTILE / ELEMENT ONTO THE HEAT PRESS (LEFT) ......................................................... 30 FIGURE 25.PULLING OUT THE PROTECTIVE FILM OF THE TPU ELASTIC FILM FROM LAYER 1 .................................................. 30 FIGURE 26. PRESSING DOWN THE HEAT PRESS DURING 20 SECONDS. ............................................................................. 31 FIGURE 27. MULTITESTER "AMPROBE" ................................................................................................................. 35 FIGURE 28. 1MM ELECTRODE POINT ........................................................................................................................ 36 FIGURE 29.MARTIDALE ABRASION TESTER................................................................................................................. 37 FIGURE 30. SPECIMENS FIXED AT THE MARTINDALE BAR .............................................................................................. 39 FIGURE 31.LED -LAMP MICROSCOPY ILLUMINATOR ..................................................................................................... 40 FIGURE 32.COMPARISON OF SPECIMENS' LSR AS A FUNCTION OF WASHING CYCLES. ......................................................... 44 FIGURE 33.KNIT1, NON-WOVEN, AND KNI2 LSR AS A FUNCTION OF WASHING CYCLES AND AXIS DIRECTION .......................... 45 FIGURE 34.WORKING WARP YARN IN WARP KNITTING LOOMS. (SOURCE: ADAPTATION OF FIGURE SHOWN IN NORM UNE EN16812_2016, PAGE 7) ........................................................................................................................... 45 FIGURE 35.NON-WOVEN LSR AS A FUNCTION OF WASHING CYCLES AND DIRECTION .......................................................... 46 FIGURE 36.KNIT 1 AND KNIT 2 LSR AS A FUNCTION OF WASHING CYCLES AND DIRECTION .................................................. 46 FIGURE 37.TRANSFER1 LSR AS A FUNCTION OF WASHING CYCLES .................................................................................. 47 FIGURE 38.LINEAR SURFACE RESISTANCE AS A FUNCTION OF NUMBER OF ABRASION CYCLE (FOR 0-WASHING CYCLE) ............... 49 FIGURE 39.LINEAR SURFACE RESISTANCE AS A FUNCTION OF NUMBER OF ABRASION CYCLE (FOR 20-WASHING CYCLE) ............. 49 FIGURE 40.COMPARISON OF SPECIMEN KNIT 1 AT THE INCEPTION ON THE WASHING CYCLE TEST (WASHING CYCLE 0) AND WASHING CYCLE 20. ..................................................................................................................................... 51 FIGURE 41.KNIT 1 WASHING SPECIMEN CONDUCTIVE SIZE (16 CM X 48 CM) ................................................................... 52 FIGURE 42.KNIT 2 WASHING SPECIMEN SIZE. CONDUCTIVE AREAS ARE < 4CM X 14 CM ..................................................... 53 FIGURE 43.IRREGULAR COLOURED AREA ON KNIT 1 AFTER WASHING CYCLE NO.20 ........................................................... 53 FIGURE 44.IRREGULAR COLOURED AREA ON KNIT 2 AFTER WASHING CYCLE NO.20 ........................................................... 54 FIGURE 45.KNIT 1 SPECIMEN AFTER WASHING CYCLE NO.20 AND 1000 ABRASION TEST .................................................... 55 FIGURE 46.NON-WOVEN SPECIMEN AFTER WASHING CYCLE NO.20 AND 1000 ABRASION TEST ........................................... 55 FIGURE 47.TPU SPECIMEN AFTER WASHING CYCLE NO.20 AND 1000 ABRASION TEST ...................................................... 56 FIGURE 48.TRANSFER 1 SPECIMEN AFTER WASHING CYCLE NO.20 AND 1000 ABRASION TEST ............................................ 56 FIGURE 49.TRANSFER 2 SPECIMEN AFTER WASHING CYCLE NO.20 AND 1000 ABRASION TEST ............................................ 57 FIGURE 50.KNIT 2 SPECIMEN AFTER WASHING CYCLE NO.20 AND 1000 ABRASION TEST .................................................... 57 FIGURE 51.LAYER-TO-LAYER ANGLE INTERLOCK STRUCTURE WITH WEFT LAYERS . SOURCE 3D WEAVING POSSIBILITIES ON AN 8 SHAFT LOOM JO - ECCM 2012 - COMPOSITES AT VENICE, PROCEEDINGS OF THE 15TH EUROPEAN CONFERENCE ON COMPOSITE MATERIALS ER - ........................................................................................................................ 61 FIGURE 52.LAYER-TO-LAYER ANGLE INTERLOCK STRUCTURE WITH WARP STUFFERS . SOURCE 3D WEAVING POSSIBILITIES ON AN 8SHAFT LOOM JO - ECCM 2012 - COMPOSITES AT VENICE, PROCEEDINGS OF THE 15TH EUROPEAN CONFERENCE ON COMPOSITE MATERIALS ER ........................................................................................................................... 61 FIGURE 53.3D MULTILAYER. SOURCE: HTTPS://WWW.SCIENCEDIRECT.COM/SCIENCE/ARTICLE/PII/S1359835X15002122 ... 61 FIGURE 54.3D CONDUCTIVE COMPOSITE PROPOSAL . SOURCE : OWN SOURCE.................................................................. 62 FIGURE 55.JACQUARD PILE HTH SIMULATION. ADAPTED FROM J.P.SINGH, S. VERMA, CHAPTER8WEAVING OF TERRY FABRICS IN WOVEN TERRY FABRICS BY J.P.SINGH, S.VERMA (ED.)WOODHEAD PUBLISHING SERIES IN TEXTILES,2017,ISBN 9780081006863. ..................................................................................................................................... 62 FIGURE 56.3DWNS CONSTRUCTION. SOURCE: ADAPTED FROM : PRODUCTION PRINCIPLES FOR A 3DWNS. LINDSEY WATERTON TAYLOR, XIAOGANG CHEN & MARTIN ANTHONY SMITH (2017) PRODUCTION PRINCIPLES FOR A T-SHAPED 3D WOVEN NODAL STRUCTURE (T-3DWNS), THE JOURNAL OF THE TEXTILE INSTITUTE. ........................................................... 63 FIGURE 57. ADAPTATION OF FIGURE 7. OWN SOURCE ................................................................................................ 64 FIGURE 58. CIRCULAR ECONOMY BEST PRACTICES REPRESENTATION. OWN SOURCE .......................................................... 67
7 List of Abbreviations / Glossary Ω Ohm AATCC American Association of Textile Chemists and Colourist Android Mobile operating system Bio-sensors Sensors in touch to skin gathering body bio signals. CB Carbon black Course(s) In knit structure: a crosswise row of loops, corresponding to the filling. Drapability The capacity of a fabric to drape Drape Drape is the term used to describe the way a fabric hangs on the body. ECG Electronic Cardiogram e-commerce Commercial transactions conducted electronically on the internet. EIC International Electro-technical Commission Electrically conductive textile products An electrically conductive textile product conducts an electrical current or supplies an electric field to a device. Electrical conduction is the movement of electrically charged particles through an electrical conductor, called an electric current. Environment / surroundings Circumstances, objects, or conditions, which surround a textile material or textile product or the user of that material or product e-textile Electronic textile ETS e-Textile System Functional textile / garment product Textile / garment product to which a specific function is added by means of material, composition, construction and/or finishing (applying additives, etc.) iOS iPhone Operating System created and developed by Apple Inc. IoT Internet of Things ISO International Standards Organization (International Organization for Standardization) Launderability/ washability The quality or state of being washable LSR Linear Surface Resistance Mass-market /mass market A market for goods produced on a large scale for a significant number of end consumers. MFT Master Final Thesis PA Polyamide PES Polyester PPE(s) Protective Personal Equipment(s) Q Research question SEM Scanning Electron Microscope Smart (intelligent) textile/garment Smart textile system Smart textile system Textile-based system which exhibits an intended and exploitable response as a reaction either to changes in its surroundings/environment or to an external signal/input Textile system Assemblage of textile product(s) and non-textile element(s) TPU Thermoplastic Polyurethane Wale (s) In knit structure: a column of loops running lengthwise, corresponding to the warp of woven fabric. Warp In woven structure: the lengthwise threads on the fabric loom Washability The capacity to be washed. Weft In woven structure: horizontal threads or filling on the fabric loom Wearable(s) Electronic device(s) conceived to be worn
1. Wearable technology, also known as “wearables”, groups all electronic devices that are conceived to be worn, usually, in close contact with the skin and to react upon external or internal (Bio) signals. Smartwatches, health tracking devices (beyond medical eyewear (Google glasses), wireless headphones, and virtual reality (VR) headsets, are some of the devices that have become popular and are entering the mass market. In 2020, market research from IDTechEx " Wearable Technology Forecasts 2021 estimated the increase in revenues and sales of wearable technology as illustrated in Figure 1. * Forecasted Figure https://www.idtechex.com/en/research Covid market for smart textiles and garments, is projected to reach the volume of Billion innovation applied to textiles is rapidly increasing, and the textile manufacturing sector in introducing Intelligent garments interconnect with our body and propose programmed actions according to bio apparel. The or WIFI to Smart or intelligent functions are also an added value that will distinguish garments beyond their fabric composition and pattern shape. Introduction Wearable technology, also known as “wearables”, groups all electronic devices that are conceived to be worn, usually, in close contact with the skin and to react upon external or internal (Bio) signals. Smartwatches, health tracking devices (beyond medical eyewear (Google glasses), wireless headphones, and virtual reality (VR) headsets, are some of the devices that have become popular and are entering the mass market. In 2020, market research from IDTechEx " Wearable Technology Forecasts 2021 estimated the increase in revenues and sales of wearable technology as illustrated in Figure 1. * Forecasted Figure 1. Wearable technology revenues and sales as a function of time. https://www.idtechex.com/en/research Covid - 19 has impacted the lifestyle habits of consumers, and today (2022) the global market for smart textiles and garments, is projected to reach the volume of Billion by 2026 innovation applied to textiles is rapidly increasing, and the textile manufacturing sector in introducing Intelligent garments interconnect with our body and propose programmed actions according to bio apparel. The bio or WIFI to iOS and Android devices (Figure 2). Smart or intelligent functions are also an added value that will distinguish garments beyond their fabric composition and pattern shape. Introduction Wearable technology, also known as “wearables”, groups all electronic devices that are conceived to be worn, usually, in close contact with the skin and to react upon external or internal (Bio) signals. Smartwatches, health tracking devices (beyond medical eyewear (Google glasses), wireless headphones, and virtual reality (VR) headsets, are some of the devices that have become popular and are entering the mass market. In 2020, market research from IDTechEx " Wearable Technology Forecasts 2021 estimated the increase in revenues and sales of wearable technology as illustrated in Wearable technology revenues and sales as a function of time. https://www.idtechex.com/en/research 19 has impacted the lifestyle habits of consumers, and today (2022) the global market for smart textiles and garments, is projected to reach the volume of by 2026 [1] instead of the initially forecasted USD $ 1.4 billion. Technology innovation applied to textiles is rapidly increasing, and the textile manufacturing sector in introducing Intelligent garments interconnect with our body and propose programmed actions according to bio - signals or environmental factors: this is the next generation of wearing bio - signals are captured by the textile sensor and transmitted via Bluet iOS and Android devices (Figure 2). Smart or intelligent functions are also an added value that will distinguish garments beyond their fabric composition and pattern shape. Wearable technology, also known as “wearables”, groups all electronic devices that are conceived to be worn, usually, in close contact with the skin and to react upon external or internal (Bio) signals. Smartwatches, health tracking devices (beyond medical eyewear (Google glasses), wireless headphones, and virtual reality (VR) headsets, are some of the devices that have become popular and are entering the mass market. In 2020, market research from IDTechEx " Wearable Technology Forecasts 2021 estimated the increase in revenues and sales of wearable technology as illustrated in Wearable technology revenues and sales as a function of time. https://www.idtechex.com/en/research - report/wearable 19 has impacted the lifestyle habits of consumers, and today (2022) the global market for smart textiles and garments, is projected to reach the volume of instead of the initially forecasted USD $ 1.4 billion. Technology innovation applied to textiles is rapidly increasing, and the textile manufacturing sector in introducing Intelligent garments interconnect with our body and propose programmed actions signals or environmental factors: this is the next generation of wearing signals are captured by the textile sensor and transmitted via Bluet iOS and Android devices (Figure 2). Smart or intelligent functions are also an added value that will distinguish garments beyond their fabric composition and pattern shape. 8 Wearable technology, also known as “wearables”, groups all electronic devices that are conceived to be worn, usually, in close contact with the skin and to react upon external or internal (Bio) signals. Smartwatches, health tracking devices (beyond medical eyewear (Google glasses), wireless headphones, and virtual reality (VR) headsets, are some of the devices that have become popular and are entering the mass market. In 2020, market research from IDTechEx " Wearable Technology Forecasts 2021 estimated the increase in revenues and sales of wearable technology as illustrated in Wearable technology revenues and sales as a function of time. report/wearable - technology 19 has impacted the lifestyle habits of consumers, and today (2022) the global market for smart textiles and garments, is projected to reach the volume of instead of the initially forecasted USD $ 1.4 billion. Technology innovation applied to textiles is rapidly increasing, and the textile manufacturing sector in introducing smart textiles to the mass market. Intelligent garments interconnect with our body and propose programmed actions signals or environmental factors: this is the next generation of wearing signals are captured by the textile sensor and transmitted via Bluet iOS and Android devices (Figure 2). Smart or intelligent functions are also an added value that will distinguish garments beyond their fabric composition and pattern shape. Wearable technology, also known as “wearables”, groups all electronic devices that are conceived to be worn, usually, in close contact with the skin and to react upon external or internal (Bio) signals. Smartwatches, health tracking devices (beyond medical eyewear (Google glasses), wireless headphones, and virtual reality (VR) headsets, are some of the devices that have become popular and are entering the mass market. In 2020, market research from IDTechEx " Wearable Technology Forecasts 2021 estimated the increase in revenues and sales of wearable technology as illustrated in Wearable technology revenues and sales as a function of time. Source technology - forecasts 19 has impacted the lifestyle habits of consumers, and today (2022) the global market for smart textiles and garments, is projected to reach the volume of instead of the initially forecasted USD $ 1.4 billion. Technology innovation applied to textiles is rapidly increasing, and there is commercial interest from smart textiles to the mass market. Intelligent garments interconnect with our body and propose programmed actions signals or environmental factors: this is the next generation of wearing signals are captured by the textile sensor and transmitted via Bluet Smart or intelligent functions are also an added value that will distinguish garments beyond their fabric composition and pattern shape. Wearable technology, also known as “wearables”, groups all electronic devices that are conceived to be worn, usually, in close contact with the skin and to react upon external or internal (Bio) signals. Smartwatches, health tracking devices (beyond medical eyewear (Google glasses), wireless headphones, and virtual reality (VR) headsets, are some of the devices that have become popular and are entering the mass market. In 2020, market research from IDTechEx " Wearable Technology Forecasts 2021 estimated the increase in revenues and sales of wearable technology as illustrated in Source forecasts -20212031/839 19 has impacted the lifestyle habits of consumers, and today (2022) the global market for smart textiles and garments, is projected to reach the volume of instead of the initially forecasted USD $ 1.4 billion. Technology there is commercial interest from smart textiles to the mass market. Intelligent garments interconnect with our body and propose programmed actions signals or environmental factors: this is the next generation of wearing signals are captured by the textile sensor and transmitted via Bluet Smart or intelligent functions are also an added value that will distinguish garments Wearable technology, also known as “wearables”, groups all electronic devices that are conceived to be worn, usually, in close contact with the skin and to react upon external or internal (Bio) signals. Smartwatches, health tracking devices (beyond medical use), smart eyewear (Google glasses), wireless headphones, and virtual reality (VR) headsets, are some of the devices that have become popular and are entering the mass market. In 2020, market research from IDTechEx " Wearable Technology Forecasts 2021 estimated the increase in revenues and sales of wearable technology as illustrated in 2031/839 19 has impacted the lifestyle habits of consumers, and today (2022) the global market for smart textiles and garments, is projected to reach the volume of instead of the initially forecasted USD $ 1.4 billion. Technology there is commercial interest from smart textiles to the mass market. Intelligent garments interconnect with our body and propose programmed actions signals or environmental factors: this is the next generation of wearing signals are captured by the textile sensor and transmitted via Bluet Smart or intelligent functions are also an added value that will distinguish garments Wearable technology, also known as “wearables”, groups all electronic devices that are conceived to be worn, usually, in close contact with the skin and to react upon external or use), smart eyewear (Google glasses), wireless headphones, and virtual reality (VR) headsets, are In 2020, market research from IDTechEx " Wearable Technology Forecasts 2021 -2031", estimated the increase in revenues and sales of wearable technology as illustrated in 19 has impacted the lifestyle habits of consumers, and today (2022) the global market for smart textiles and garments, is projected to reach the volume of US$5.9 instead of the initially forecasted USD $ 1.4 billion. Technology there is commercial interest from Intelligent garments interconnect with our body and propose programmed actions signals or environmental factors: this is the next generation of wearing signals are captured by the textile sensor and transmitted via Bluet ooth Smart or intelligent functions are also an added value that will distinguish garments
15 But despite the aforementioned performances, smart textiles and smart garments have not yet reached mass-market consumers as initially expected; the reason may be their wholesale price and the reticence of the end-consumer to invest in a garment with a potential loss of its functional properties after domestic laundry [8],[9],[10],[11],[14],[16]. Some manufacturers of smart garments recommend "gentle hand-wash", but this suggestion is against the consumer habits. Mass-market consumers avoid hand-washing and, in addition nowadays, the trend among singles is to live in small city-centre studios. On many occasions the studio does not have washing equipment, and the laundry is done in self-service laundry. The poor usability of these expensive garments is still refraining the mass-market demand and solving the washability effects has become a key concern for manufacturing companies. According to Naan Ju et al. (2021) survey [3], consumers are still reluctant to include smart clothing in their wardrobe; the survey, which included answers from 320 adults, concluded that it is still necessary to decrease the consumers’ perceived risk of the rapid obsolescence of smart garment linked Apps, as well as to improve the performance, durability, and availability of smart clothing. Until year 2021, the ISO Standard used to assess washing durability of e-textile systems was the same as for conventional fabrics: ISO6330_2021 "Domestic washing and drying procedures for textile testing"; but the standard was not conceived for e-textiles and, consequently, the mechanical stress, as well as, washing temperature and washing cycle duration, affected the results. In May 2021, the International Electro-technical Commission (EIC) organization that prepares and publishes globally International Standards for electrical, electronic, and related technologies, published Part 4-1 for IEC 63203 "Wearable electronic devices and technologies". The IEC 63203-204-1 applies to "Electronic textileTest method for assessing washing durability of leisurewear and sportswear e-textile systems" (IEC 63203-204-1) ; to avoid misinterpretation the EIC 63203-204-1 clarifies the terms and definitions for its application: "e-textile system: product made from textiles and integrated electronics that together perform one or more functions; Conductive textile: textile with electrical conductivity; leisurewear and sportswear: clothing worn to enjoy leisure and sports (excluding accessories like swatches and glasses)"(IEC 63203-204-1); Statistics predict the generalization among the mass market of wearable technology, but forecast will only become a reality if all the components tolerate the launderability, and domestic washing does not affect the garment's functionality. 1.1 Rationale and Motivation Until today, smart textiles and smart garments are focused on research essays, medical use, or high-technology industry sectors; their presence in the end consumer is limited to professional athletes or to a limited number of PPE clothing (Smart PPE); their laundering, if any, is performed by industrial launderings under strict washing specifications.
16 When commercialized to the market, garments must include a compulsory care instruction label with washing instructions on washing, bleaching, drying, ironing, and dry clean instruction (Figure 13). Each country and commercial zone agreement may have its own regulation; in the European Union, the labelling is ruled by the Regulation (Eu) No 1007/2011 of the European Parliament, September 2011. Figure 13.Labelling laundry symbols. Source: https://www.fibre2fashion.com/industry-article/8788/yourguide-to-garment-labeling-requirements-for-clothing. In the case of smart garments, the care instruction label is key for the performance of a smart garment functionality. As mentioned in the introduction, smart textiles gather a signal and transfer the data to a device. To this end, they must include conductive yarns and sensors, as well as an integration system or manufacturing process to embed all these elements and form a sole composite material. There are still issues to identify and overcome in order to ensure performance reliability during the lifecycle of a smart garment when including electronics into or onto fabrics, and launderability is one of the main challenges when evaluating the readiness of a conductive material for the mass market. When buying a Smart garment, the end consumer must know the tentative usage period and must have clear and feasible laundry instructions. At present, there are too many unknown gaps and only seldom technologic consumers are keen to buy a costly garment with uncertain life usage. The research focuses in studying the effects of domestic care and abrasion, on linear surface resistance performance of several selected 2D conductive composite and its surface changes. The study also compares the effects on different 2Dcomposite materials to spot the differences found due to different structures and conductive techniques.
17 The results and evaluation and conclusions will be structured according to the following research questions: Q1: Which is the effect of domestic laundry machine washing to the electrical linear resistance of the material surface? Q2: Which is the effect of abrasion to the electrical linear resistance of the material surface? Q3: Which are the effects of domestic laundry machine washing and abrasion on the specimen's surface appearance? The study uses a quantitative approach - laboratory testing of linear surface resistance and abrasion test - as well as a qualitative approach based on visual evidence of the surface specimens. 1.2 Objectives This study focuses on the effects of domestic launderability and abrasion on the performance of electronic textiles, and hence, it relates to the need of electronic textile manufacturers to improve the material's conductivity because, according to related literature, the washing conditions affect the reliability of the smart garment "After 19 washings under extreme washing conditions, disconnections have been observed......and it is predictable than the higher the number of washings, the greater the impact on the product's operability"(IEC 63203-204-1). Conductive textiles are the essence of smart textiles (also known as e-textiles or electronic textiles); without the transfer of data there would interaction or reaction to stimuli to bio or environmental signals, and no possibility of tracking. The conductive textiles are part of the success of smart garments and its forecasted sales increase. As part of a garment, the conductive textiles can monitor body signals, can act as ON/Off switchers, activate reactions of vibration, heating, release of chemicals, or conduct any order as any other IT system would do. The study aims to analyse the effects of domestic washing care on two surface resistance properties: electrical resistance and abrasion resistance and, therefore, the smart garment usability related to their conductive properties. This study has been conducted in a laboratory with no garment wearing tested on real people; to reproduce the changes in the material surface due to garment wearing, an abrasion resistance test has been conducted. The experiment also includes magnifier observation of the 2D composite surface appearance at the initial and final stage of the experiment; the aim of the visual observation is to compare the effects of washing and abrasion test on the specimen's surface. Consumers judge the overall visual appearance as a sign of garment aging. The laboratory treatments have been carried out in the Laboratory for Textile Mechanical Testing of the Textile Department ETSIAAT-UPC.
18 1.3 Scope of the Study This study includes the analysis of the effects on linear surface resistance of reagents, washing stress and surface rubbing of six 2D composite conductive specimens when submitted to domestic washing and abrasion resistance. It also includes the observation of the effects of washing and abrasion treatment on the 2D surface conductive materials. The criteria for the selection of the materials may be found in Chapter 3.1. "Criteria for the selection of the conductive and non-conductive textile substrates for this MFT ", but one of the main priorities has been to select fabrics with a comfortable skin-touch. The laundry of work-wear and safety and protective garments is usually performed by industrial laundries, therefore this MFT is not going to consider this type of applications for the study. Smart garments made from conductive textiles may suffer other changes due to domestic washing and usability like dimensional change, colour fastness, changes due to perspiration and loss of resilience properties but these changes will not be analysed in this Master Final Thesis (MFT). This thesis will focus on the domestic laundry effects in 2D conductive materials formed by lamination or transfer printing of conductive ink onto a conventional fabric; other types of electronic textiles will not be considered : embedded conductive element within a fabric or a yarn, conductive yarn embroidered onto a textile surface, a textile transmission tape - conductive yarns integrated into a flexible textile base or a tapeor woven structures made from metal yarn, metal-wrapped yarn or metal -filled yarn. The reason is that 2D conductive material formed by silver-plated and a ground material as well as printed circuits -with conductive inkhave proven to be more comfortable to wear[4], [5]. The bistretch is comfortable to wear and 2D composite adapts its surface to body movement. The scope of work to be conducted for the achievement of the stated objective is listed hereunder (scope of work a, b, c and d); the sequence of the conductivity test, abrasion test and magnifier observation after the periodical laundering cycles considered for this study, is shown in Table 4 "Sequence of the conductivity test, the abrasion tests and magnifier observation to be conducted in this study" (Chapter 4."Methodology"). The scope of work below listed covers the purpose for being included in this MFT and its contribution to the object of this study. a) Washing test on domestic equipment. Several factors influence the washing treatment on domestic equipment: mechanical action of the washing process, applied chemicals (detergents and softeners) , temperature and processing time. The overall objective of the washing process is to remove soil, odour and germs and restore the garment to its initial wearing conditions; but smart textiles are hybrid components and the mentioned factors affect the electronic components and their functionality. The washing test is based on ISO 6330_2021 and EIC 63203-204-1. b) Conductivity testSurface electrical resistance. Smart wearables are conceived to detect and react to bio-signal; therefore, the surface resistance of conductive textiles must be below 1000 [Ohm/sq.]
19 According to Ohm's law, the relation between Resistance (R) and current (I) are inversely proportional1: ( )= ; for same voltage, the higher the Resistance, the less the material conducts the electricity. The conductivity testing is based on the Standard AATCC Test Method 76-1995, which measures the property of the material; the conductivity test will be measuring the "linear resistance" property of the material by which it resists the amount of current passing through it. The Resistance as property is expressed in Ohm/sq. c) Abrasion resistance. The abrasion resistance will be measured in accordance with ISO 12947_4 :1998/Cor.2002, "Assessment of appearance change"; this part of the standard applies to the assessment of the surface appearance change and covers specimens of all textile fabrics, including non-woven. Part_4 has been chosen for the abrasion experiment because one of the specimens has a layer of TPU and the values for part_2 "Determination of specimen breakdown" and part_3 " Determination of mass loss", would not be comparable with the values for the other specimens. d) Visual observation. Observation of the material surface is essential to analyse the effect of the washing and abrasion test on the appearance of the fabric. The visual observation will be conducted by means of a camera and a led-light illuminator. 1.4 Requirements In order to carry out this project, we have prepared five 2D composite specimens combining conventional fabric and conductive material by lamination or transfer printing. A sixth specimen has been included in the study at a later time (after washing cycle 1); the 2D conductive specimen was property of the Director of this thesis, Mrs Elina Ilen, and the rationale for its inclusion was to compare two parallel specimens with same woven structure but different yarn density. It total six specimens have been tested. For the washing test, we have searched for a specific washing powder and household equipment meeting the ISO 6330_2021 and EIC 63203-204-1criteria. The washing powder used is "Norit Bebe" and the washing equipment "AEG Lavamat L60699". The lamination of the conductive and non-conductive layers has been performed in a heat press for textile transfer. In addition, it is necessary to have a Martindale tester for the abrasion resistance test, a multitester to measure the linear surface resistance test and a camera and led light to observe the surface appearance change of the 2D composite after the washing and the abrasion tests. The SEM microscope of the Laboratory for Textile Mechanical Testing of the Textile Department ETSIAAT-UPC was not available. 1 Ohm law, a fundamental law of electricity, stating that the voltage at the terminals of an ideal resistor is proportional to the current in the resistor (www.electropedia.org IEV ref 131–15–08)
1.5 The sequence of the study structure is repre Literature Research and Review of the Selection of conductive textiles and Preparation of specimens for testing Selection of standards and norms and Preparation of specimens for testing All the visual doc The laboratory treatments have been conducted in the Laboratory for Textile Mechanical Testing of the Textile Department ETSIAAT Study Structure The sequence of the study structure is repre Literature Research and Review of the State of the Art Selection of conductive textiles and Preparation of specimens for testing Selection of standards and norms and the testing methods Washing resistence test conductivity test Preparation of specimens for testing abrasion resistance conductivity test Visual observation Results and Analysis Conclusions All the visual doc umentation included in this study is from own source. The laboratory treatments have been conducted in the Laboratory for Textile Mechanical Testing of the Textile Department ETSIAAT Study Structure The sequence of the study structure is repre Figure Literature Research and Review of the State of the Art Selection of conductive textiles and Preparation of specimens for testing Selection of standards and norms and the testing methods Washing resistence test + conductivity test Preparation of specimens for testing abrasion resistance + conductivity test Visual observation Results and Analysis Conclusions umentation included in this study is from own source. The laboratory treatments have been conducted in the Laboratory for Textile Mechanical Testing of the Textile Department ETSIAAT Study Structure The sequence of the study structure is repre Figure 14 .Project scheme, (source: own source) • Search of published literature on: composite materials, Trends on interactive textiles (Smart textiles), Commercially available conductive textiles, Consumer s' trends on functional garments Literature Research and Review of the • Selection of the conductive and non material.Preparation of the specimens according to agreed dimensions. Elaboration of the 2D conductive composite specimens by lamination of conductive and non layers a by heat preassure . (Chapter 3) Selection of conductive textiles and Preparation of specimens for testing • ISO 6330_2021 standard / AATCC test method 76 12947_4 :1998/Cor.2002 . equipment , load and washing powder . multitester test and camera (Chapter 3). Selection of standards and norms and • Sequence of the washing and conductivity testing (Chapter 4). • Preparation of the specimens based on ISO12947_4:1998/Cor.2002 specifications. Sequence of the abrasion and conductivity testing (Chapter 4). Preparation of specimens for testing • Sequence of the visual observation (Chapter 4). • questions (Chapter 5). • Chapter 6 : Consideration and decision regarding. alternative solutions. (Chapter 6). • Discussion of the solution (Chapter 7). • Summary of the conclusions (Chapter 10). 20 umentation included in this study is from own source. The laboratory treatments have been conducted in the Laboratory for Textile Mechanical Testing of the Textile Department ETSIAAT The sequence of the study structure is repre sented in Figure 14. .Project scheme, (source: own source) Search of published literature on: composite materials, Trends on interactive textiles (Smart textiles), Commercially available conductive textiles, Consumer s' trends on functional garments Selection of the conductive and non material.Preparation of the specimens according to agreed dimensions. Elaboration of the 2D conductive composite specimens by lamination of conductive and non layers a by heat preassure . (Chapter 3) ISO 6330_2021 standard / AATCC test method 76 12947_4 :1998/Cor.2002 . equipment , load and washing powder . multitester test and camera (Chapter 3). Sequence of the washing and conductivity testing (Chapter 4). Preparation of the specimens based on ISO12947_4:1998/Cor.2002 specifications. Sequence of the abrasion and conductivity testing (Chapter 4). Sequence of the visual observation (Chapter 4). Results and Evaluation acording to the reaserch questions (Chapter 5). Chapter 6 : Consideration and decision regarding. alternative solutions. (Chapter 6). Discussion of the solution (Chapter 7). Summary of the conclusions (Chapter 10). umentation included in this study is from own source. The laboratory treatments have been conducted in the Laboratory for Textile Mechanical Testing of the Textile Department ETSIAAT sented in Figure 14. .Project scheme, (source: own source) Search of published literature on: composite materials, Trends on interactive textiles (Smart textiles), Commercially available conductive textiles, Consumer s' trends on functional garments Selection of the conductive and non material.Preparation of the specimens according to agreed dimensions. Elaboration of the 2D conductive composite specimens by lamination of conductive and non layers a by heat preassure . (Chapter 3) ISO 6330_2021 standard / AATCC test method 76 12947_4 :1998/Cor.2002 . Preparation of washing equipment , load and washing powder . multitester test and camera (Chapter 3). Sequence of the washing and conductivity testing Preparation of the specimens based on ISO12947_4:1998/Cor.2002 specifications. Sequence of the abrasion and conductivity testing (Chapter 4). Sequence of the visual observation (Chapter 4). Results and Evaluation acording to the reaserch questions (Chapter 5). Chapter 6 : Consideration and decision regarding. alternative solutions. (Chapter 6). Discussion of the solution (Chapter 7). Summary of the conclusions (Chapter 10). umentation included in this study is from own source. The laboratory treatments have been conducted in the Laboratory for Textile Mechanical Testing of the Textile Department ETSIAAT -UPC. sented in Figure 14. .Project scheme, (source: own source) Search of published literature on: Conductive materials, 2D composite materials, Trends on interactive textiles (Smart textiles), Commercially available conductive textiles, Consumer s' trends on functional garments (Chapter 1 & 2). Selection of the conductive and non - condutive material.Preparation of the specimens according to agreed dimensions. Elaboration of the 2D conductive composite specimens by lamination of conductive and non layers a by heat preassure . (Chapter 3) ISO 6330_2021 standard / AATCC test method 76 Preparation of washing equipment , load and washing powder . Martidale test, multitester test and camera (Chapter 3). Sequence of the washing and conductivity testing Preparation of the specimens based on ISO12947_4:1998/Cor.2002 specifications. Sequence of the abrasion and conductivity testing (Chapter 4). Sequence of the visual observation (Chapter 4). Results and Evaluation acording to the reaserch Chapter 6 : Consideration and decision regarding. alternative solutions. (Chapter 6). Discussion of the solution (Chapter 7). Summary of the conclusions (Chapter 10). umentation included in this study is from own source. The laboratory treatments have been conducted in the Laboratory for Textile Conductive materials, 2D composite materials, Trends on interactive textiles (Smart textiles), Commercially available conductive textiles, (Chapter 1 & 2). condutive material.Preparation of the specimens according to agreed dimensions. Elaboration of the 2D conductive composite specimens by lamination of conductive and non - conductive ISO 6330_2021 standard / AATCC test method 76 - 1995 /ISO Preparation of washing Martidale test, Sequence of the washing and conductivity testing Preparation of the specimens based on ISO12947_4:1998/Cor.2002 specifications. Sequence of the abrasion and conductivity testing (Chapter 4). Sequence of the visual observation (Chapter 4). Results and Evaluation acording to the reaserch Chapter 6 : Consideration and decision regarding. Summary of the conclusions (Chapter 10). The laboratory treatments have been conducted in the Laboratory for Textile (Chapter 1 & 2). conductive 1995 /ISO Martidale test, ISO12947_4:1998/Cor.2002 specifications. Sequence of the abrasion and conductivity testing (Chapter 4).
21 2. Review of the state of the art Despite the increasing interest of the textile and apparel industry to launch textile wearables to mass market, there is little literature and studies regarding the effects of domestic laundry on functional properties or the product life textile electronics. The literature search done has evidenced that today's trends in technological wearables are the research on optical fibre sensors for e-textiles, to improve the response to chemical stimuli for detection of biomarkers, bimolecular, and other components from body fluids able to track or prevent pathologies [5] and the integration of graphite fibres in e-textiles [23]. The industry is aware of the low wear fastness of textile wearables and the correlation between domestic laundry and the loss of conductivity properties. The research done on Smart garments have spotted that the majority mention "safe to wash" in their marketing campaigns and recommend hand-wash. Taking as an example the maintenance recommendations from company Wearablex for its yoga pant Nadi X (Chapter 1: Introduction) , twenty -five washes would mean a lifespan of 25 weeks (6 months) for a yoga pant worn every week and only washed once per week. A mass-market user will request a higher lifespan of 25 washes; this number may be sufficient for professional athletes with different incomes and interests on technological wearable, but is not convincing for a non-professional user. Vapour and perspiration are normal phoneme experienced when practicing sports; so the launderability of the garment is essential [25]. 2.1 Conductive textiles An electronic textile is a textile combined with a conductive element. It is functional textile with electronic properties. A conventional conductive element can be embedded into the fabric, stitched or embroidered on to the fabric surface , by printing, coating and lamination of the fabric, by metal-plating or by woven structures using conductive yarns or fibres. A sensor is a device that can respond to an external stimulus by generating a measurable signal. [6] (Figure 15) . Figure 15. Electrocardiography (ECG) Sensor. Source : https://www.pluxbiosignals.com/products /electrocardiography-ecg-sensor-1
22 A fibre-base sensor device is an electrically conductive textile responding to external stimuli but flexible, lightweight and comfortable to wear (Figure 16). Figure 16.Textile-sensor Source: https://materialdistrict.com/material/textile-sensor/textile-sensor-pla10184/ Thanks to their conductive properties, an electrically conductive textile can act as a sensor, an antenna, data transmission or a textile electrode, and is the preferred conductive material for a smart textile system (Figure 7) ( "Textile-based system which exhibits an intended and exploitable response as a reaction either to changes in its surroundings/environment or to an external signal/input" . ISO/TR 23383:2020(E.) Figure 17. Smart Textile System. Source : Lina Rambausek This MFT will consider electrically conductive textiles made by electroplating of silver onto a textile structure. There are several good conductive 2metal fibres available on the market as Gold (Au), Silver (Ag), Copper (Cu), Titanium (Ti), Aluminium (Al), Nickel (Ni) and stainless steel, but this MFT has tested only Silver fibre (Ag); Silver and Gold are the two most conductive 2 A material is considered to have a "good electrical conductivity" if it has a specific conductivity (resistivity) of > 102 S/m (<104 Ω·cm).A material is considered to have "ohmic behaviour" if its resistance follows Ohm law. www.electropedia.org IEV ref 131–15–08.
23 metals skin [7],[8] In addition to its conductivity, Silver has antibacterial properties, which is an add-on when considering fabrics exposed to body-fluid emissions and in contact with human body, it is biocide according to §67 EU Biocide Regulation, and has no, or rare, allergic reactions. Silver is less costly than Gold and, therefore, a more affordable material for mass production purposes. There are several techniques for metal-plating, the most common ones used for metalplating and convert conventional yarns onto e-textiles are: Electroplating or electrodeposition and electroless plating and chemical solution process (CVD). Electroplating is a process in which a film is formed on the surface of the substrate by means of deposition of the electrochemical reduction of the metal ions from the electrolyte. Electro-less plating forms metallic deposition by chemical reaction but there is no consumption of the substrate material; the process uses the reduction of the metal ions but only at the surface of a catalytic substrate. In the CVD technique, a substrate is treated with an oxidant and then exposed to a monomer vapour, which then polymerises into a coating. [6], [7],[8] . According to Kony Chatterjee et al. [6] metallization techniques often fail in creating a uniform coated surface with the same thickness and density in all the coated area. Uniformity is essential for obtaining stable conductivity; the lack of reliable process is a factor to consider and must be improved. The conductive textile structure may be woven, knitted or non-woven. Metal yarns tend to be rigid and uncomfortable to skin touch; compared to woven structures, knitted fabrics are soft and more flexible, and its elongation and resilience properties are better than woven structures with similar count yarns. The 2D conductive composite specimen has two layers: A conductive fabric acting as textile electrode (first layer) and a non-conductive conventional fabric (second layer). Both layers are attached by lamination by means of hot pressure, forming a 2D conductive composite material. 2.2 Effects of domestic laundry on conductive fabrics This MFT will study the conductive properties of 2D composite material after washing and abrasion testing. The resistance tests aim to reproduce the effects of domestic care and garment use and analyse the reliability of the tested conductive textiles [9],[10],[19],[26]. Laundry washing machines soak garments in a bath with chemical reagents and by means of mechanical rotating movements, induce the separation of stain and fat from the substrate surface. The bath is heated to a certain temperature to favour the kinetics of the molecules, and dissolved washing detergent, temperature and scrubbing movements remove the undesired particles, which are expelled from the washing drum together with the washing water by rapid spinning movements. This continuous mechanical action affects the thickness and structure of the yarn, responsible for the surface stability and resistance of the fabric. The chemical reagents may affect the molecular bonds and alter fibre microstructure; and water oxidizes metals and cause dysfunctions. Conductivity is also affected by temperature: the warmer the water, the higher the conductivity, water impurities and water hardness. To finalize, the composition of the drum
24 load - load's fibre compositionand its weight are different in each domestic washing cycle. 2.3 Effects of abrasion resistance on conductive fabrics During the lifecycle of a composite material, the usage tends to affect the composite's surface due to contact and friction with other elements; the rubbing may cause cracks on the metal-plated surface and cause conductivity malfunctions. Rubbing can also remove completely the conductive coating from the yarn or fabric or cause the separation of the fabric or even the breaking of yarns affecting the connection and the conductivity.[11],[17],[19]. The abrasion test gives information on the wear fastness of the 2D conductive composite and can determine the performance and quality of the electroplating process as well as the stability of the substrate or fabric used as ground material. 3. Specimen characterization and preparation 3.1 Criteria for the selection of the conductive and non-conductive textile substrates for this MFT The conductive textile substrates have been selected according to the following criteria: ● Commercialised conductive textile material of common use. ● Different structures for comparison purposes. ● Variable manufacturing technologies. ● With elasticity and comfortable touch to skin. The non-conductive textile material has been selected according to the following criteria: ● Fabric of common use in the sport and active wear industry. According to the above criteria the MFT has considered a silver-plated warp knitted fabric. Silver is the preferred by researchers for textile electrodes to be in contact with the skin due to its similar conductivity with gold, affordable price in comparison to gold and its antibacterial properties. Metalized fabrics are already commercialised, and the leading companies exhibit in international fairs like Techtextil in Germany. There are several reliable manufacturers of metalized fabrics and yarns like Statex GmbH one of the leaders in metallised fabrics and yarns. (https://techtextil.messefrankfurt.com/ frankfurt/en/exhibitor-search.html?q= metallized % 20fabrics).
31 Figure 26. Pressing down the heat press during 20 seconds. 5º Check the two layers form a well-glued 2D composite material and place them in a flat surface for at least 24 hours at room temperature. The two transfers 2D composites (Transfer 1 and Transfer 2) had to be heat pressed a second time at higher temperature (160ºC). After the first pressing remained nontransferred ink. The 2D conductive composite specimens are referenced as follows (Table 3): Table 3.References of the 2D specimens Reference Layer 1 Conductive textile /element Layer 2 non-conductive fabric "Knit 1" Knit 1 Non-conductive fabric "Non-woven" Non-woven Non-conductive fabric "TPU" TPU Non-conductive fabric "Transfer 1" Transfer 1 Non-conductive fabric "Transfer 2" Transfer 2 Non-conductive fabric "Knit 2" Knit 2 Non-conductive fabric
32 4. Methodology 4.1 Testing process The sequence of the conductivity test, abrasion test and magnifier observation after the periodical laundering cycles considered for this study, is shown in Table 4. Table 4.Sequence of the conductivity test , the abrasion tests and magnifier observation to be conducted in this study Sequence Conductivity test Abrasion test Visual Observation test Inception (Washing cycle No.0) After washing cycle No.1 After washing cycle No.5 After washing cycle No.10 After washing cycle No.15 After washing cycle No.20 The testing methodology is based on ISO 6330_2021 standard (washing test) and AATCC test method 76-1995 (conductivity test after washing and abrasion) but adapted to the objective of this MFT: to contribute to a better understanding of the effects of domestic laundry and abrasion on the surface resistance of conductive textiles. The rationale for the modifications is explained in Subchapters 4.1.1 and 4.1.2. The abrasion test is conducted according to ISO 12947_4 :1998/Cor.2002 without any modification. 4.1.1 Modifications to washing methodology ISO 6330_2021 standard The ISO 6330:2021standard relates to "domestic washing and drying procedures for textile testing. The procedures are applicable to textile fabrics, garments or other textile articles which are subjected to appropriate combinations of domestic washing and drying procedures" (Textiles — Domestic washing and drying procedures for textile testing, ISO 6330:2021, page 2). Unfortunately, the standard is not conceived specifically for smart garments or conductive fabrics, so this study has considered adequate for its objective to adapt certain testing parameters to home laundry of conductive fabrics.
33 Previous studies on launderability of conductive textile coincide that the best washing conditions to maintain the functionality of conductive textile are easy care or delicate programs, room-temperature water, and air dried. The ISO 6330:2021 standard temperature washing parameter was adapted to meet these recommendations. The water temperature parameter for a mild washing (3 N) was lowered from 30+/- 3ºC to room temperature (21 +/- 3ºC). The automatic washing equipment used for the experiment is not a reference machine Type A (annex Anormative-), but a horizontal axis, front-loading type popular in many Spanish households. The washing powder used for the experiment is not a referenced detergent in ISO 6330_2021 standard annex I - normativebecause the referenced detergent is not available to the end consumer. The washing powder used for the experiment complies with the requirements of: non-phosphate, without optical brightener and ph7. 4.1.2 Modifications to surface conductive test, AATCC test method 76-1995 The measured distance between the two electrodes is adapted to the size of the skin electrodes - usually 10.0 cm x 3.0cmand was reduced from 10.0cm x 10.0cm to 8.0cm x 2.0cm The EIC 63203-204-1 was not considered for this MFT because the EIC standard requests conductivity test in accordance with EN 16812:2016: to set the measurement points at 100mm each to the right and left of the centre of conductive areas. These measurement points cannot be considered if we are wearing a smart textile system with a printed electronic circuit or other type of textile sensors with a size < 100mm. 4.2 Conductivity after washing Conductivity measurements were conducted at the inception of the experimental art (cycle 0) and after the first washing cycle (cycle 1). Following to cycle 1, conductivity tests were conducted at 5-cycle washing intervals until cycle 20. Specimens were placed on a flat surface and dried at room temperature, once dried, the conductivity was measured. The washing and conductivity test processes are explained in below subchapters 4.2.1 "Washing procedure" and 4.2.2."Conductivity measurement procedure". 4.2.1 Washing procedure Former studies [10], [11] on conductive textile launderability agree that conductive textiles should be washed with Easy Care or delicate program at room temperature water, at a maximum tumbler of 400 rpm for 4 minutes and no bleaching or softener agents. The washing powder should be free of phosphates and optical brightener and with pH7; airdried is preferred and no ironing (ISO 6330:2021standard).
34 This study has considered these criteria as a starting point and the washing tests were conducted according to the parameters listed in Table 5. Table 5.Washing parameters considered for this study Equipment AEG Lavamat L60699 load 2.5 kgs * Nº of Cycles 20 Washing procedure / time Easy care /30 min Tumbler / rpm /time 400 rpm / 4 min Washing temperature 21ºC +/- 3ºC (room temperature). Water is not heated. Washing powder Non-phosphate without enzymes and no optical brightener, pH7, “NORIT BEBE"** Average water hardness (CaCo3) 330 mg/l de CaCo3. Drying procedure Air dried at room temperature (21ºC +/- 3ºC) *The dry mass of the samples is counterweighted with non-smart garments made of cellulosic and /or polyester fibre at 50% - Ballasts Type II according to ISO 6330_2021- ** Manufacturer: AC Marca Home Care SA, Spain. CIF: A08053423, Technical composition and security file in Annex I (Norit Bebé) After washing cycle 1, washings were conducted in 5-cycle intervals until cycle 20. At the end of each testing cycle, the specimens were placed until dry on a flat surface to avoid wrinkles, tension, and an irregular evaporation of its water content. The specimens were not tumbled or twisted. As mentioned in Table 5, the dry mass of the samples was counterweight until 2.5 kgs with a blend of optical white conventional garments made of cellulosic and polyester fibre. The technical and security file of the washing powder - Norit Bebémay be found in the annex 4.2.2 Conductivity measurement procedure Linear Surface Resistance as a function of laundry cycles was used to analyse the performance of the 2D conductive materials. The conductivity test was performed based on AATCC test method 76-1995 with a 2-point probe multitester. In this study, the conductive property to consider the 2D composite suitable for domestic washing is as follows: Linear Surface Resistance ≤ 999 [Ohm/sq.] = the 2D composite is suitable for domestic washing treatment Linear surface Resistance ≥ 1000 [Ohm/sq.] = the 2D composite is not suitable for domestic washing treatment
35 The reason for this criterion is because 1,000 [Ohm/sq] is the maximum linear surface resistance accepted in sensor electrodes gathering ECG signals. The conductivity test was performed by means of a multitester (Figure 27) Figure 27. Multitester "AMPROBE" Except for the printed electronic circuit (specimens Transfer 1 and Transfer 2), the measurements were conducted in vertical and horizontal axis. The purpose was to analyse the anisotropic/ isotropic conductivity property. The testing was done considering below conditions and parameters: Water is a poor electrical conductor; to ensure no moisture was present, the conductivity tests were performed 24 hours after the specimens were dried. The specimens were placed onto an insulated surface. Except for specimen Transfer 1 and Transfer 2, the distances measured for the testing were as follows: o Vertical axis : 2.0 cm o Horizontal axis: 2.0 cm o Horizontal axis: 8.0 cm The distance measurements between the two electrodes were done with the assistance of a calibrated ruler. The measurement of the linear surface resistance Transfer 1 and Transfer 2 was done placing the electrodes in the two printed conductivity circles (one in each circle). The conductive printed circuit has two specific conductive areas connected by a printed curved pigment. The transfer has 3 circuits of different lengths: o circuit 1: 5.5 cm o circuit 2: 8.5 cm o circuit 3: 13.0 cm The surface resistance value was noted down after a period of 60 seconds of contact between the electrode and the specimen surface. During this lapse, the multitester screen showed different values until reaching a steady number.
36 The TPU specimen resistance values were noted down after a time lapse of 120 seconds. It was decided to increase the time duration because since the first testing (cycle 0) TPU specimen showed unsteady values at 60 seconds time measurement. Five parallel measurements from random places / locations were made at both axis (vertical and horizontal axis) of specimens Knit 1, Non-woven, TPU and Knit 2. The average value was calculated and it is shown in Table 6, Chapter 5 "Results and Evaluation". For Transfer 1 and Transfer 2, three parallel measurements from random places / locations were made and at each printed circuit; the average value was calculated and it is shown in Table 6, Chapter 5 "Results and Evaluation". Due to the diameter of the conductive area of the printed circuits, 15 mm, it was considered that the average value of three random measurements was an accurate LSR measurement. In certain cases, the values were going up rapidly and within a band of 1000 ohm or even more. When this situation occurred for all three measurements, the decision was to consider the measurement "uneven", because it was impossible to agree and note down a valid value. To mention that the end point of the electrode used was not flat (as recommended in certain literature [12] to measure surface resistance on soft specimens) but pointed of 1mm diameter size (Figure 28) Figure 28. 1mm electrode point To avoid any doubts on the influence of the pointed electrode on the surface resistance values, several tests were also performed with an oblique position of the electrode on the fabric. The resistance values were similar and it was decided that the shape and the contact surface area of the electrode did not affect the measurement. The way in which testing electrodes contact the material to test has a noteworthy influence on the result of the measurement. The contact pressure of the two conducting electrodes on the fabric surface is related to surface resistance. As all the tests were conducted by the same person and using the same testing methodology, the measurement contact pressure has not been considered a variable affecting the results. According to the Standard AATCC Test Method 76-1995, the surface resistance value was noted down after a time period of 60 seconds of contact between the electrode and the specimen surface. During this lapse, the multitester screen showed different values
37 until reaching a steady number. But in certain measurements the value shown in the screen remained uneven after 60 seconds, with values going up rapidly and within a band of 1000 Ohm or larger. When this situation occurred for all five measurements, the decision was to record the measurement as "uneven", because it was impossible to agree and note down a valid value. 4.3 Conductivity after abrasion resistance procedure Conductivity tests were conducted on the specimens after the abrasion test. The abrasion test was conducted at the inception of the experimental art (cycle 0) and after cycle 20. For comparison purposes, the linear surface resistance was measured after 250, 500 and 1000 abrasion cycles. Due to the tentative usage of the conductive textile - to be worn for leisure or sport activity-, the 1000 abrasion cycle test was considered sufficient to assess the visual changes of the specimens. In case of work-wear or PPE garments, the number of abrasion cycles should have been increased beyond 2000 cycles. (i.e., fire fighters’ glove palm hand surface must be level 3 at 2000 cycles - norm EN 659:03-). The abrasion resistance was conducted in accordance with ISO 12947_4 :1998/Cor.2002, "assessment of appearance change". This part of the standard is applicable to the assessment of the surface appearance change and covers specimens of all textile fabrics, including non-woven. Part "4" was chosen for the abrasion experiment because one of the specimens has a layer of TPU and the values for ISO 12947_2 "Determination of specimen breakdown" and ISO 12947_3 "Determination of mass loss", would not be comparable with the values for the other specimens. The equipment used is a Martindale abrasion tester manufactured by Shirley Developments LTD (Figure 29). Figure 29.Martidale abrasion tester
38 The specimens for the abrasion test resistance were prepared according to the ISO 12947_4 :1998/Cor.2002 standard: The specimens must be cut in a circular shape of 38mm diameter. The specimens are taken from at least 100 mm from the fabric edge. All the specimen contains the conductive element, or all the conductive element must be included in the specimen. In addition, the abrasion test has been done taking into consideration below testing conditions: 24 hours before the testing, the specimens are placed on a flat surface to relax tensions. The abrasive medium is 100% wool fabric. Visual documentation of the specimens fixed in the Martindale bar and prepared for the abrasion test (Figure 30) Knit 1 Non-woven
39 TPU Transfer 1 Transfer 2 Knit 2 Figure 30. Specimens fixed at the Martindale bar
40 The conductive procedure after the abrasion test was conducted as indicated. The conductivity test was performed based on AATCC test method 76-1995 with a 2-point probe multitester (Figure 27). The specimen to test was placed onto an insulated surface. Three measurements of the linear surface resistance of the specimen were done placing the two electrodes in three random locations of 1.5 cm distance. The distance measurements between the two electrodes were done with the assistance of a calibrated ruler. The specimen average LSR value was calculated and it is shown in Table 7 and Table 8, Chapter 5 "Results and Evaluation". 4.4 Visual observation of the specimens' surface appearance The visual observation was conducted at the Laboratory for Textile Mechanical Testing of the Textile Department ETSIAAT-UPC university with the assistance of a led lamp microscopy illuminator (Figure 31). The images were magnified at 7x, 10x and 15x and captured with a camera for visual documentation purposes. Figure 31.Led -lamp microscopy illuminator The evaluation criteria for the abrasion tested have been done according to the ISO 12947_4 1998 standard: "... the evaluation of the abrasion of the textile fabric resistance is determined from assessment of the appearance change" [Determination of the abrasion resistance of fabrics by the Martindale method — Part 4: Assessment of appearance change — ISO 12947_4 :1998/Cor.2002, page 2] The visual documentation of the specimens' surface appearance due to the washing and abrasion test, is included in Chapter 5: Results and Evaluation.
47 The assessment of two parallel specimens helps to analyse the reliability of the manufacturing process. Figure 37, plots the LSR of Transfer 1 and Transfer 2 as a function of washing cycles. Figure 37.Transfer1 LSR as a function of washing cycles The specimens Transfer 1 and Transfer 2, show similar LSR behaviour but we can still record differences: Both specimens have a stable LSR measurement until washing cycle 10. At washing cycle 15 Transfer 1 circuit 3 records a sharp increase of the LSR, from 1.9 to 4.73 [Ohm/sq.] and lowers on cycle 20, to 1,45 [Ohm/sq.] Transfer 1 circuit 2 gives uneven values at cycle 20 and cannot be recorded. Transfer 2 seems to have a more stable LSR though out the washing cycles, but its circuit 1 also gives uneven LSR values on cycle 20. The conclusion for the printed conductive ink is that this technique is not reliable after washing cycle 20; three out of six LSR values cannot be recorded because they are uneven. Based on Table 6 values, Table 9 records the LSR difference between washing cycle 0 and washing cycle 15 and its increase in percentage8. For comparison purposes, Table 9 shows only those specimens and cycles for which there is a complete measurement recording9 Table 9. LSR difference between washing cycle 0 and cycle 15 and its increase in percentage 8 Percentage Increase=((Final Value − Starting Value) / |Starting Value|)×100 9 Knit 2 is not included because there are no measurements for washing cycle 0 and cycle 1. Washing cycle 20 is not included because certain specimens' measurements were uneven and could not be recorded. 0 1 2 3 4 5 0 5 10 15 20 Linear Surface Resistance [Ω/sq.] Number of washing cycles Transfer 1 and Transfer 2 Transfer1 circ.1 (5.5cm) Transfer1 circ.2 (8.5cm) Transfer1 circ3 (13.5cm) Transfer2 circ.1 (5.5cm) Transfer2 circ.2 (8.5cm) Transfer2 circ.3 (13.5cm) 2D Specimen Axis direction and distance (cm) LSR difference between c 0 and c15 [Ohm/sq.] [%] Knit 1 wales (2.0cm) 1,28 213.33 wales (8.0cm) 2,02 288.57
48 Although all specimens (except TPU) show LSR records < 1000[Ohm/sq], the higher the percentage value, the lower the reliability of the conductive textile after the domestic laundry. According to Table 9, specimen Non-woven records the lower LSR increase on percentage between washing cycle 0 and cycle 15 in all the three measurements; it is the 2D conductive composite specimen showing less effects on LSR after 15 washing cycles. 5.2 Effects of abrasion on linear surface resistance The plotting10 of Table 7 and Table 8 LSR values as a function of number of abrasion cycles (Figure 38 and Figure 39) visually highlights the effects of the 20 washing cycles on the behaviour of the LSR. Figure 3811 shows the LSR values after abrasion conducted on the 0-washing cycle specimens. The LSR decreases on the first abrasion test (250 cycles), with a tendency to stabilize after 500 and 1000 cycles on Knit1, decrease on Transfer 1 and Transfer 2, and increase on Non-woven specimen. 10 TPU is not included in the plotting because the LSR values are > 1000 Ohm/sq. Conductivity property for domestic washing appropriate for bio-sensors.(Subchapter 4.3.2. "Conductivity test methodology). 11 Knit 2 specimen is not represented because, as mentioned in Chapter 3.3, the specimen could not be included in the study until washing cycle No.5. courses (2.0cm) 1,18 196.66 Non-Woven Vertical axis (2.0cm) 0,48 72.72 Vertical axis (8.0cm) 0,5 62.50 Horizontal axis (2.0cm) 0,32 45.71 Transfer 1 Circuit 1 (5.5cm) 1,05 175.0 Circuit 2 (8.5cm) 1,4 175.0 Circuit 3 (13.0cm) 3,53 294.16 Transfer 2 Circuit 1 (5.5cm) 0,8 133.33 Circuit 2 (8.5cm) 0,7 77.77 Circuit 3 (13.0cm) 0,6 46.15
49 Figure 38.Linear Surface Resistance as a function of number of abrasion cycle (for 0-washing cycle) Figure 39 plots LSR values after the abrasion test conducted on the 20-washing cycle specimens. * Knit 2 specimen is tested until washing cycle 15, because washing cycle 20 gave uneven values Figure 39.Linear Surface Resistance as a function of number of abrasion cycle (for 20-washing cycle) Specimens Knit 1 and Knit 2 show a similar tendency, but with Knit 2 values higher than Knit 1. Besides increasing the structure stability, higher density implies more yarn-length, which increases the Resistance12. The Non-woven 2D conductive composite seems to have a similar LSR behaviour from abrasion 250 to abrasion 1000 cycles. Non-woven specimen also shows values near zero at 1000 abrasion cycles. The reason could be the defibrillation of the non-woven fibre due to abrasion. This would mean a loss of the non-conductive material mass and the conductive metal parts would then arise to the surface. The specimen should have been observed with a SEM microscope before and after the experimental art. 12 = , for the same cross-sectional area (A) and resistivity of the conductor () the resistance (R) directly proportional to the length (l). 0 0,2 0,4 0,6 0,8 1 0 500 1000 1500 Linear Surface Resistance [Ω/sq.] Number of Rubs Linear surface resistance as function of number of abrasion cycle (0 washing cycle) Non - woven Transfer 1 Transfer 2 Knit 1 0 2 4 0 500 1000 1500 Linear Surface Resistance [Ω/sq.] Number of Rubs Linear surface resistance as function of number of abrasion cycles (20 washing cycles) Non-woven Transfer1 Transfer2 Knit 1 Knit 2*
50 Transfer 1 and Transfer 2 show similar LSR values no matter the washing cycles. But the effects of abrasion seem to favour the conductivity property of the conductive material Both specimens record almost zero resistance at 1000 abrasion cycles no matter the washing cycle. It is an unexpected finding because the abrasion done on the conductive area has certainly altered the surface and removed a part of the printed circuit. May be the printed circuit has a coating that maintains stable the resistivity of the conductive textile. In any case, to understand the reason for this LSR behaviour it is necessary to observe the specimens before and after the abrasion test with a SEM microscope and to analyse the components of the conductive ink. Although TPU 2D conductive material cannot be considered for conductive textile in touch with the skin, it is important to mention that the records of the LSR done on the 20washing cycle and 1000 abrasion test gave a stable value instead of an uneven value as in all the precede measurements. The abrasion must have altered the properties of the surface eliminating13 the element causing these unstable values. To have an in-deep understanding of these LSR values, it would be necessary to know the components of the TPU conductive material, in special, the coating done on the TPU material. Based on the LSR values of 2D specimens conducted at 20 washing cycle and after 0,250, 500 and 1000 abrasion cycles (Table 8), Table 10 records the LSR difference between abrasion 0 cycles and 1000 cycles, and its difference in percentage. Table 10.LSR difference between 0 and 1000 abrasion cycles for specimens after washing cycle 20, and its increase or decrease in percentage 20 washing cycle specimens difference between 0 and 1000 abrasion cycles [Ohm/ sq.] [%] Knit 1 0,55 18.21 Non-woven 0,2 66.66 Transfer1 -1,33 -91.72 Transfer2 -0,67 -95.71 Knit 2 -0,13 -6.31 The values on Table 10 evidence the effect of the abrasion on the linear surface resistance of the washed specimens. Knit 1 and Knit 2 show a stable LSR from 0 cycles to 1000 cycles: 18.21% in Knit 1 and - 6.31% in Knit 2. 13 The visual observation subchapter (Subchapter 5.3.) contains documentation where it is visible the TPU surface appearance difference : from shiny to dull colour tone.
51 Table 10 also highlights the decrease of the LSR in Transfer 1 and Transfer 2 and the increase of Non-woven LSR from 0.30 [Ohm/sq.] to 0.50 [Ohm/sq.], 66.6%, although both values are within the acceptance on LSR value fixed in this MFT for considering a specimen acting as bio-sensor suitable for domestic laundry. 5.3 Effects of washing cycles and abrasion on specimens' surface appearance after 20 washing cycles 5.3.1 Effects of washing cycles on specimens' surface appearance after 20 washing cycles The visual surface comparison of the specimens before and after 20 washing cycles indicates changes only in the knit structure specimens (Knit 1 and Knit 2); the surface of the other 2D conductive materials (Transfer 1, Transfer 2, Non-woven and TPU) remain with a similar visual appearance after the 20-washing cycle test. The visual documentation of Transfer 1, transfer 2, Non-woven and TPU can be found in the annex. Figure 40 shows the comparison of the surface of Knit 1 at cycle 0 and after washing cycle 20. Figure 40.Comparison of Specimen Knit 1 at the inception on the washing cycle test (washing cycle 0) and washing cycle 20. The observed wrinkles and pleads on Knit 1 specimen may be caused by the mechanical stress of the washing process. The LSR was specifically tested in the inside of the wrinkle / plead; the distance measured between the two electrodes was 8 cm in order to compare the value with the 8 cm measurement of the non-wrinkled surface. Table 11 indicates the recorded LSR values.
52 Table 11.LSR values for Knit 1 specimen inside and outside the wrinkle / plead (20 washing cycles) Specimen Distance between electrodes Non-wrinkle surface Inside the wrinkle Knit 1 8 cm 3.86 [ohm/sq.]* 7.2 [ohm/sq.] ** * Value obtained from Table 6. Linear surface resistance after each washing cycle ** Average value of three measurements. The value recorded in table 11 indicates an LSR increase of 86.50% inside the wrinkle/ plead; which means an important decrease on the conductivity property of the material. Knit 1 and Knit 2 have the same weaving construction, but Knit 2 does not show any pleads or wrinkles on its surface after washing cycle 20. The reason could be the different size of both specimens; Knit 1 has a surface of 16cm x 48cm and Knit 2 is cut14 in smaller sizes not bigger than 14cm x 4 cm to fit a bio-sensor size15. (Figure 41 and Figure 42) Figure 41.Knit 1 washing specimen conductive size (16 cm x 48 cm) 14 Knit 2 specimen entered the study as seen in Figure 42 15 bio-sensor is < 3cm x 10 cm.
53 Figure 42.Knit 2 washing specimen size. Conductive areas are < 4cm x 14 cm Knit 1 and Knit 2 show an irregular darker colour on their surface after the washing test (Figure 43 and Figure 44) Figure 43.Irregular coloured area on Knit 1 after washing cycle No.20
54 Figure 44.Irregular coloured area on Knit 2 after washing cycle No.20 The darker coloured area of Knit 1 and Knit2 is also measured (Table 12) but the measurements show no significant LSR difference due to colouring. Table 12.LSR values for Knit 1 and Knit 2specimen inside and outside the coloured area (20 washing cycles) Specimen Distance between electrodes Non-coloured surface Coloured area Knit 1 8 cm 3.86 [ohm/sq.]* 3.83 [ohm/sq.] ** Knit 2 2 cm uneven uneven * Value obtained from Table 6 .Linear surface resistance after each washing cycle. ** Average value of three measurements. 5.3.2 Effects of abrasion on specimens' surface appearance after 20 washing cycles and 1000 cycles of abrasion The visual observation of the specimens after washing cycle No. 20 and abrasion test (1000 abrasions) indicates changes in all the specimens between the rubbed and nonrubbed area. To compare the rubbed and non-rubbed surface, the visual documentation shows the specimens samples after the abrasion test; the centre area, diameter 30mm, is rubbed and the outside area is non-rubbed.
55 Knit 1 specimen observation The rubbed area has a dull colour compared with the non-rubbed area, and looks blurry due to the surface change. (Figure 45). Figure 45.Knit 1 specimen after washing cycle No.20 and 1000 abrasion test Non-woven specimen observation Figure 46 illustrates the effect of the abrasion on the non-woven surface; the rubbed area is more shinny than the non-rubbed area. It seems as the metal parts have been "polished". Figure 46.Non-woven specimen after washing cycle No.20 and 1000 abrasion test
56 TPU specimen observation As illustrated in Figure 47, the TPU rubbed area has changed in colour and in surface structure. Figure 47.TPU specimen after washing cycle No.20 and 1000 abrasion test The rubbed area is whitish and has lost its shiny look. It is also observed that the TPU surface has small holes and cracks. Transfer 1 and Transfer 2 specimen observation Figure 48 and Figure 49 illustrates the effect of the abrasion in the white paste; the rubbed area is darker and it is visible the ground black fabric. The effect is the same for both transfers. Figure 48.Transfer 1 specimen after washing cycle No.20 and 1000 abrasion test
The benefits of this proposal are that the filling composite is a non be filled with different functional components. Figure Waterton Taylor, Xiaogang Chen & Martin Anthony Smith (2017) Production principles for a T woven nodal structure (T The benefits of this proposal are that the filling composite is a non be filled with different functional components. Figure 56 .3DWNS construction. Source: adapted from : Production principles Waterton Taylor, Xiaogang Chen & Martin Anthony Smith (2017) Production principles for a T woven nodal structure (T The benefits of this proposal are that the filling composite is a non be filled with different functional components. .3DWNS construction. Source: adapted from : Production principles Waterton Taylor, Xiaogang Chen & Martin Anthony Smith (2017) Production principles for a T woven nodal structure (T - 3DWNS), The Journal of The Textile Institute. The benefits of this proposal are that the filling composite is a non be filled with different functional components. .3DWNS construction. Source: adapted from : Production principles Waterton Taylor, Xiaogang Chen & Martin Anthony Smith (2017) Production principles for a T 3DWNS), The Journal of The Textile Institute. 63 The benefits of this proposal are that the filling composite is a non be filled with different functional components. .3DWNS construction. Source: adapted from : Production principles Waterton Taylor, Xiaogang Chen & Martin Anthony Smith (2017) Production principles for a T 3DWNS), The Journal of The Textile Institute. The benefits of this proposal are that the filling composite is a non .3DWNS construction. Source: adapted from : Production principles Waterton Taylor, Xiaogang Chen & Martin Anthony Smith (2017) Production principles for a T 3DWNS), The Journal of The Textile Institute. The benefits of this proposal are that the filling composite is a non - woven and nodes can .3DWNS construction. Source: adapted from : Production principles for a 3DWNS. Lindsey Waterton Taylor, Xiaogang Chen & Martin Anthony Smith (2017) Production principles for a T 3DWNS), The Journal of The Textile Institute. woven and nodes can for a 3DWNS. Lindsey Waterton Taylor, Xiaogang Chen & Martin Anthony Smith (2017) Production principles for a T - shaped 3D woven and nodes can for a 3DWNS. Lindsey shaped 3D
64 7. Discussion of the proposed solutions The alternative solutions proposed in Chapter 6, are based on placing the conductive yarn in the inside of the 2D conductive composite avoiding the contact of the conductive element with the external mechanical forces of domestic laundry washing. But it is important to mention that these solutions are adequate for transferring data but not suitable for textile sensors gathering bio signals; these sensors have to be in contact with skin. The gathering of data cannot be done if the sensor is not in direct touch with the body. The woven structures proposed in Chapter 6 should be modified for having the conductive yarn in touch with the skin body in those areas where the conductive yarn is acting as a bio-sensor. Another alternative could be to use different conductive techniques for gathering biosignal (sensor) and the other actions. As seen in Figure 7, a smart textile system is composed of different parts (Figure 57), the conductive textile for biosensor could have the conductive material on its surface and the conductive textile for transferring data could be placed in the insert of the 2D conductive composite Figure 57. Adaptation of Figure 7. Own source Ultimately, the bio-sensor area could be protected during laundry with a piece of conventional fabric clipped to the 2D composite with hook-and-eye fasteners. All solutions are based on silver-plated yarn because of the antibacterial characteristics of this metal. Plating is also the proposed coating technology for the conductive yarn because the knitted fabric is flexible, and has a drapability comparable with fabrics done with conventional yarn. As mentioned in Subchapter 3.1., the textile industry is already commercialising silver-plated conductive yarns for home textile and smart textile systems. Examples of conductive yarn17: Shieldex® Wrapped Yarn . Core: 85/1 Viscose & Wrapped Material: Shieldex® 44/10 PA 6.0 . The viscose core yarn can be dyed to any colour. Silver colour is not affected. (Statex GmbH) 17 Research done in : https://techtextil.messefrankfurt.com/frankfurt/en/search.html?q=silver-plated on 14/06/2022.
65 − Shieldex® Wrapped Yarn-stretch Roica 33/1 V550 SC/Elastan & Wrapped Material: Shieldex® 33/10 PA 6.0. (Statex GmbH) − Shieldex® Wrapped Yarn-dyed red . Core: 100/26 2ply PA 6.6 & Wrapped Material: Shieldex® 44/10 PA 6.0 (Statex GmbH) − Swicosilver : Plasma Silver coated yarn with an ongoing metal adhesion and high conductivity (substrate : Polyester) count range [dtex]: 440 f 96, 710 f 144, 1090 f288,....., 2244 f 199. (Swicofil AG) Swicofil AG is proposing plasma technology for the silver coating process, Statex GmbH seems to propose electro deposition but this information is not formally certified. Plasma coating is a sustainable technology, because the it reduces the consumption of water and chemicals used in conventional plating process.
66 8. Budget summary The final cost of the execution of this MFT is shown in Table 13. A detailed budget breakdown may be found in the document "BUDGET" Table 13.Final cost of the execution of the project. Concept Cost € Cost the material used for the preparation of the 2D conductive specimens 200.00 Depreciation cost of the use of the laboratory technological equipment 36.00 Cost of the use of the laboratory facilities 2160.00 Total Cost 2396.00 €
67 9. Analysis and assessment of environmental and social implications The latest textile manufacturing environmental trends are focus on embedding Circular Economy principles on the textile manufacturing value chain (Figure 58) Figure 58. Circular Economy best practices representation. Own source According to Ellen MacArthur Foundation ( https://ellenmacarthurfoundation.org/), zero waste to landfill is the goal of Circular Economy. But the achievement of the full re-use of the components of a product is a task that starts at the product design conception. Design is the key to move forward in Circular Economy principle "Design out waste and pollution" (Ellen MacArthur) ; but if a product is not friendly designed to fulfil this principle, the end user will find hard to give the product a sustainable end or continuation. One of the key issues for re-use a product is the complexity of the disassembling or its repairing damaged parts. Technological wearables are a compound of materials often difficult to disassemble and - from the research done for this MFTno spare parts or repairing is offered to the consumer. The 2D conductive composites used for the execution of this MFT are made of a conductive fabric layer - containing silver and polyamideadhered with thermopolyurethane to a second layer made of polyamide and elastane. Five different nonbio degradation components forming a non-detachable unit. The other issue affecting the sustainability of smart textile units is its low span life. The literature on the reliability of conductive materials for smart textile units [8],[9],[10],[11],[14],[16]. agree in the limited number of washing cycles. A short use of the smart garment / smart textile unit is correlated with the increase of such products in the landfill.
68 10. Conclusions This chapter recalls in brief the background and motivation for the research done in this study, and it presents a final synthesis based on the interpretations of the results obtained by the experimental art. It also provides recommendations for future research according to the findings of this MFT. According to recent market studies (2022), the global market for wearable technologies is projected to reach the annual revenue volume of USD 5.9 billion by 2026 instead of the initially forecasted USD 1.4 billion. The wearable technology or technology applied to textiles and conceived to be worn, has experienced a rapid development and the textile manufacturing sector is expecting a mass-market demand of smart textile systems: hybrid products between technological devices and wearing apparel. Smart textile systems gather bio-signals and external signals and transfer data in order to produce an intended response. Their health and protection applications are countless, at present the most known and demanded ones are related to continuous monitoring of life sigs and biosensors for health sector and sport activities. But despite its benefits, the end consumer is still reluctant to invest in smart textile systems commonly known as smart garments. The poor usability is refraining the boosting of sales, the cause is due to domestic laundry machine effects to the electrical linear resistance of the material surface. The MFT objective was to answer below research questions: Q1: Which is the effect of domestic laundry machine washing to the electrical linear resistance of the material surface? Q2: Which is the effect of abrasion to the electrical linear resistance of the material surface? Q3: Which are the effects of domestic laundry machine washing and abrasion on the specimen's surface appearance? Concerning Q1: The 20 washing tests were done at room temperature water (21ºC +/-3ºC) to avoid the effects of temperature on the conductive material. Following suggestions of previous researches, the washing tests were done in absence of chemicals and tumbler, with ph7 washing powder, easy-care 30-minute washing programme duration and air-dried on a flat surface. But despite the precautions, the last five washing cycles were critical for the LSR. In nine out of eighteen LSR measurements after washing cycle 20, the LSR values were uneven and could not be recorded. The printed circuit , Transfer 1 and Transfer 2, showed also uneven results in three out of nine LSR measurements after washing cycle 20. The difference of yarn density in two parallel warp knit structures with same structure and yarn composition, has no effect on the LSR reliability after washing test 20, but it seems to be correlated with the LSR's stability. Knit 2 specimen shows a more stable LSR value throughout the washing cycles in comparison with Knit 1 LSR values.
69 The more stable LSR values were recorded from the Non-woven specimen; but nonwoven technique for wearing apparel is not an option because it is not conceived to be repeatable washed. The results on TPU LSR indicate that this conductive material is not appropriate to be used in textile sensors for bio-signals. All the recorded TPU LSR values were > 1000 [Ohm/sq]. Except TPU specimen, the other 2D conductive materials show good LSR values until washing cycle 15, and hence, can be used in textile sensors for bio-signal gathering. Concerning Q2: The results from the experimental abrasion art show that abrasion has no effect on electrical surface resistance of the material surface (LSR). The difference of LSR between 0 and 1000 cycles is not significant. Concerning Q3: The visual observation of the surface appearance showed pleads and wrinkles on the knitstructure specimens' surface after cycle 15. The LSR measured inside the wrinkles doubled the LSR value on flat surface. The pleads and wrinkles may be caused by mechanical stress of the domestic laundry machine. Recommendations for future research: This study has considered different structures and conductive technologies, and the LSR results have been similar after washing cycle 20. It must be studied the mechanism of plating and what causes the appearance of pleads and wrinkles on the conductive material surface at early washing cycles; as well as the uneven LSR values. Hand wash is not a valid solution for mass-market. Smart textile systems have to be washable as any other every-day conventional garment. In a addition, it would be needed to repeat the experimental art with following indications: Repeat the study, with the same specimens and experimental art, but changing the temperature washing parameter to 30ºC and 40ºC. The conductivity test should be done with golden plates more suitable for linear surface measurement on soft materials as fabrics. Abrasion test to be done up to 2000 cycles. Observation with SEM microscope instead of visual observation.
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