Smart Textiles – Adding Value to Sri Lankan Textiles The Electronic Textiles Option (Handout)

Smart Textiles – Adding Value to Sri Lankan TextilesThe Electronic Textiles Option

Dr Tilak DiasSchool of MaterialsThe University of Manchester, UK

Tilak Dias

• All current commodity textiles are passive;

i.e. not capable of adapting to environmental

changes

• Current technical textiles are engineered to

perform within a defined set of parameters; may

have the ability to adapt to changes within very

narrow bandwidth of environmental changes

Introduction

Question

What are they ?

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Next generation of textiles will be active and

intelligent;

i.e. they would be able to adapt to changes in

the environment

Introduction

SMART & Intelligent Knitted Structures

Core Elements

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Knitted transducers

Intelligent signal processing

Knitted actuators

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Background

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Background

Research team:

• Anura Fernando

• Edward Lay

• Kim Mitcham

• Ravindra Monaragala

• Ravindra Wijesiriwardana

• William Hurley

Research in Electro-textiles

• Heat generating knitted structures

• Knitted transducers and sensors

• Light emitting fabrics

• Electronically active yarns

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Electrically Active Knitted Structures

Electro Conductive Area (ECA)

Concept of creating textiles with significant electrical properties:Incorporate conductive elements into the structure

knitted structure

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•

•

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Advantage of using knitted structures

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Science and Technology Base

Use of electro-conductive fibres/yarns

Metal yarns (mono-filament and multi-filament)

Metal deposition yarns

Carbon fibres and yarns

Conducting polymeric yarns

Stainless steel yarn

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Creation of ECA

Use of electro-conductive fibres/yarns

Metal yarns (mono-filament and multi-filament)

Metal deposition yarns

Carbon fibres and yarns

Conducting polymeric yarns

PA yarn vacuum coated with Ag nano layer

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Creation of ECA

Use of electro-conductive fibres/yarns

Metal yarns (mono-filament and multi-filament)

Metal deposition yarns

Carbon fibres and yarns

Conducting polymeric yarns

Silicone monofilament yarn loaded with Carbon (0.5mm diameter); FabRoc®

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Creation of ECA

Computerised flat-bed knitting technology to create

three dimensionally shaped seamless stockings

Stoll CMS 330.6, E18

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Scan2Knit Technology

• Precision positioning of fibers in 3D space

• Ability to create seamless 3D structures

• Multilayer structures

• True seamless garment knitting techniques

• “Scan2Knit” technology

Advantages of using modern computerised flat-

bed knitting technology to create medical textiles

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Base structure

ECA

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Conductive pathway 2

Example of a knitted sensorConductive pathway 1

Unit Cell - Stitch Electrical Equivalent Circuit

RH

RH

RLRL

Modelling

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Calculation of RH and RL

A

LR

leg

L

RL Resistance of the stitch leg

Lleg Yarn length in the stitch leg

A Yarn cross sectional area

ρ Resistivity of yarn

A

LR head

H

RH Resistance of the stitch head

Lhead Yarn length in the stitch head

A Yarn cross sectional area

ρ Resistivity of yarn

Modelling

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Equivalent resistive mesh circuit of the ECA

Dimensions of the ECA: m courses x n wales

Modelling

Relationship between equivalent resistance and stitch density of the ECA

Assumption: Lleg = 2 Lhead

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05

1015

20

0

10

2010

12

14

16

18

20

22

Equ

ival

en

t R

esi

stan

ce (

Req

)

Current Distribution in Stitch Heads

Current Distribution in Stitch Legs

Temperature Distribution in Stitch Heads

Temperature Distribution in Stitch Legs

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Theoretical Prediction of Current Distribution

ThermoKnit® heater elements (ECA)

Power Vs Temperature (Room temp: 25°C ) Voltage Vs Average Steady State Temperature (Room temp: 25°C)

Heating Glove

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Conductive pathways

Motivation:Development of Next Generation of Textiles for the Automotive Industry

Knitted Switch Technology “K-Switch”

• Heating textiles

Industry Requirement:

• Textile based switches and sensors with electro conductive pathways

• Light emitting textiles (headliners)

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Knitted structure with 4 dual ECAs (K-Switches)

Knitted structure 20mm

ECA2

ECA1

Constructional information: The minimum gap between the ECAs:• Yarn filament diameter;• Stitch length

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Principle of operation:

Measurement of DC resistance between

the two ECAs

K-Switch Technology

DC Resistance variation

Determined with a precision digital multimeter under two wire resistance measurement configuration at 0.1s sample rate

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Operation of the K-Switch

Principle of operation:Measurement of the DC resistance between the two ECAs

K-Switch Technology

DC Resistance variation with time

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Observation: less than 300µs settling time

K-Switch Technology Applications

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Analysis

Advantages:

• Easy and reliable manufacture

• Higher degree of design capability (3 yarn jacquard knitting)

• Cost effective manufacture

• Higher durability and life time

• Straightforward integration of K-Switches for different applications

K-Switch Technology

Limitations:

• Simple electronics

• Switch characteristics depends on skin resistance

• Ineffective to other materials

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Modelling of Impedance between the ECAs

K-Switch Technology

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Cole-Cole model equivalent circuit of the ECA - Skin - ECA Impedance

K-S

wit

ch T

ech

no

logy

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Imp

ed

ance

in M

Ω

Frequency in MHz

Open circuit impedance is 0.1954 MΩ at frequencies greater than 2 MHz

Influence of the measurement frequency on the impedance - open circuit of the ECAs

K-S

wit

ch T

ech

no

logy

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Impedance characteristics of K-Switch Closed circuit of the ECAs

K-S

wit

ch T

ech

no

logy

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Impedance characteristics of K-Switch Closed circuit of the ECAs

Electro-Luminescent Fibre Structures

Theoretical background:Exposure of an electroluminescent substance to a high frequency electrical field radiate light

The state-of-the-art

EL polymer sheetsScreen printing micro-encapsulated phosphors (Osram) on to plastic sheets

Plastic sheet (base)

Silver layer (µm)

2 dielectric layers (µm)

EL layer (µm) Conductive transparent layer (µm)

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EL Yarn Technology

Motivation:

Develop EL Yarns which could be integrated into textile structures

1. Electro-conductive yarn2. Dielectric layer3. EL layer4. Transparent protective

layer5. Conductive wire

Concept

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Experimental Rig

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Knitted EL Samples

Activated – low frequency

Activated – high frequency

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Not activated

Application of EL Fibres

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• Light Emitting Textiles

• Transport sector, passenger cabin design of vehicles; e.g. headliners, carpets, upholstery

• Advertising industry; e.g. flexible and drapable billboards and notice boards

• Buildings; e.g. ceilings, walls, carpets

• Household products; e.g. curtains, furniture fabrics, wall hangings, lamp shades, decorative products

• Safety and security products

• Light Emitting Braids and Ropes• Safety and security products• Decorative and fashion products

Suggestion from School of Medicine, University of Manchester

Background

Initiation of partnership between Imaging Science and Biomedical Engineering (ISBE), Medical School; Digital Signal Processing Group (DSPG), School of Electrical & Electronics, and Department of Textiles (UMIST) in 2002

Setting-up research team for Science & Technology development

Initial funding from The Department of Trade and Industry, UK

Garment System for vital sign monitoring

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Research Achievements

• Creation of Science base for knitted transducers• Knitted dry electrodes• Knitted strain gauges• Knitted inductive sensors • Knitted conductive pathways

• Development of technology for producing a garment with integrally knitted sensors and conductive pathways

• Development of vest with 2 lead ECG (proof of concept)

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Commercialisation of Technology

• Raised funds by SmartLife® for development of core technology in the University (SoM, ISBE, DSPG)

• Development of “Health Vest” with 3 leads ECG, Respiratory and Skin Temperature monitoring

• Development of hardware and signal processing software

• IPR protected by UMIP1 core patent

• IPR assigned to a group of entrepreneurs

• Formation of a joint venture company by UMIPSmartLife® Technology Ltd

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2004 2007

20

04

SmartLife® Health Vest

Signal comparison

Signal from standard Ag/AgCl Gel electrodes Signal from SmartLife® electrodes

Signal Section

Amplitude (mV) Duration (ms)

Ag/AgCl Vest Ag/AgCl Vest

P wave 0.2 0.3 120 120

QRS complex 2.0 2.5 80 80

T wave 0.5 0.5 240 240

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Target Markets

1. Health, Wellbeing & Homecare Market size e.g. cardiovascular: ECG US$8bn1

Predictive monitoring

Clinical monitoring of patients in their own homes

2. Sports Estimated market size US$2bn – Professional Personal monitoring Training, lifestyle, personal

3. Hazardous Environment – first responders, military Estimated market size US$2bn

[1] Global Market For Patient Monitoring devices US$11.4bn (Frost & Sullivan 2005)

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Current Research

Sensor sock for drop foot detection

High frequency textile antenna

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Electronically functional yarns

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Future ……

Fibres and yarns with

sensors, transducers

and activators

Fibres/Yarn Manufacture

Fabric Manufacture

Garment Manufacture

GA

RM

ENT

Key process steps Integration of electronic devices with apparels

1st

Ge

ne

rati

on

1st

Ge

ne

rati

on

2n

dG

en

era

tio

n

3rd

Ge

ne

rati

on

Apparel Manufacturing Process Interface

Active and sensory micro-devices

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Technology is based on the encapsulated area not exceeding 110% of the thread thickness

Electronically active and sensor fibres

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Vision

The development of novel technology for

fabricating electronically active and sensor

fibres which will be the basic building blocks of

the next generation ‘SMART’ fibrous materials

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Micro-device Encapsulation Technology

Involves encapsulating devices with a flexible hermetic seal for mechanical, thermal and electrical protection

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μ-devices:

• electronic chips

• magnetic devices

• optical devices

• thermal devices

Schematic diagram of a yarn device

• Development of the concept of encapsulating

• Mathematical modelling

• Design and development of an experimental rig

• Demonstrator E-Yarn with a working diode (LED) and RFID tag

MET Platform

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MET Platform

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INVENTION

Micro-device Encapsulation Technology Platform

Prototype Demonstrator ?

Yarn with a working Diode (0.4 x 1.0 x 0.3 mm LED)

Light Emitting Fibres

Energised

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Demonstrator 1

Light Emitting Garments

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Events Garments

RFID Fibres

Aim: Development of MET for embedding Hitachi MU Tag

Demonstrator 2

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Development of sensory yarn capable of:

• Monitoring strain/stress

• Sensing temperature

• Pressure measurement

• Sensing fluids/liquids

Current Research

Development of light emitting fabrics

• Active fashion garments

• Displays

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Thank You