The Bombay Textile Research Association

Mumbai

ASTM-Workshop on Smart Textiles,

Chicago,USA

26th June 2016

Development of Fabric Based Sensors for Smart Textile

Applications-Mrs. Smita Deogaonkar-Baride & Mr. V. K. Shinde

• BTRA was established in 1954 as research association by textile millowners of Mumbai to provide research and consultancy support toIndian Textile Industry.

• To undertake research and other scientific work in connection with thetextile trade or industry and other trades or industries allied therewith oraccessory thereto.

About BTRA

Technical Services

Consultancy in shop floor problems

Utilities /

Conservation

Quality &

Environment

Management

Decentralized

Sector

Training Services

Need based training on all

aspects of textiles/technic

al textiles

Research Projects

Government funded

Private funds &

In house

Testing Services

(ISO-17025)

Physical & chemical testing

Polymer & Eco-Parameters testing

Geotextiles Lab

Soil Mechanics

Lab

Technical textiles / composites testing

Microbiology

For more details-

Website-www.btraindia.com

Email-btra@vsnl.com

-91-022-2500 -2652

-91-022-2500-3652

Main Activities

Source- A Roadmap on Smart Textiles- Textile Progress, June 2010

Communication

Data Processing

PoweringActuator

Sensor

Applications of Conductive Textiles

•Smart Textiles

Antistatic applications

Surface resistivity(ohm/sqr.):• Very Good : 106–108

• Good : 108–109

• Poor : 109-1010

• Insufficient : >1010

EMI Shielding

Efficiency w.r.t. Surface resistivity(S.R.)-• 0–20 dB: Low (S.R.-104)

• 20–40 dB: Average (S.R.- 1)• 40–70 dB: Good (S.R.-10-2)

• 70–90 dB: Excellent (S.R.-10-4)

•Resistive Heat Generation

Power Density (100mW/in2)•Smart Textiles

S.R. ≈ 100-1000 ohm/square

Low

Medium

High

Conductivity range * www.esd.org** A. Varesano et al. Synthetic Metals 159(2009) 1082- 1089***http://www.enthone.com/resources_detail.aspx?Page=perfacc.ascx

Applications Vis-à-vis Conductivity Requirements

Metal Yarns

Blend of metal &

textile fibres

Traditional Conductive Textiles

Solution- Conductive Polymers

Metallic coating

Abrasion of m/c parts

Metalized hand

Poor Comfort

Complex Process

Cost

Methods Limitations

Non-homogenous blends

Poly(phenylene-vinylene)

n

n

S

n

n

Polypyrrole

Polythiopene

Polyaniline

Source- G. Wallace and co-workers ,Conductive Electroactive Polymers-CRC press, 20003

Poly(thienylene-vinylene)

Poly(para-phenylene)

Poly(phenylenesulfide)

nN

Poly(pyridine)

NH

Poly(diphenylamine)

Conducting Polymers

Polymerization methods

•Chemical Polymerization

•Electrochemical Polymerization

•Interfacial Polymerization

•Plasma Polymerization

•Copolymerization

Polymerization

• Substrates-

Woven: Cotton, Polyester, Polyester/Cotton blend

Nonwovens: Jute, Polypropylene

• Coating substance- Intrinsic Conductive Polymers (ICP’s)

• Method used: Oxidative in-situ chemical polymerization

Experimental

Indian Patent Filed

Oxidant dispensing

mechanism

Temp. regulating

system Reaction Bath

Monomer

solution

Reaction set- up

BTRA’s method of in-situ chemical Polymerization

Nonwoven PP / Jute fabric

Nonwoven PP / Jute fabric

Monomer Treatment for

I hr

.

Addition of Oxidant at

controlled temp

Addition of Oxidant at

controlled temp

Polymerization for 3hrsWashingWashing

Conducting PP / Jute, samples is

ready

Deposition of ICP’s on Jute & PP Nonwoven

• Electrical Conductivity

• EMI Shielding Properties

• Morphological Studies (SEM Studies)

Characterization

•AATCC Test Method 76-2005

S.R. = Resistance X Width of Electrodes

Distance between electrodes

Unit – ohm/square (Ω/) Where, size of the square is immaterial.

Measurement of Electrical Surface Resistivity

• ASTM-D-257 Test

Concentric ring probe Method

Suitable for samples having resistance in the range of 106

TO 1010

ohms/square.

Measurement of Electrical Surface Resistivity

S.R. = Resistance X 2 πr

Distance between two electrode (cm)

Where,

r = radius of inner concentric ring

ASTM-D-4935-2010

• EMI shielding effectiveness is attenuation of an electromagnetic

wave produced by its passage through shield.

• Expressed as decibel(dB).

• Method used: Coaxial transmission line in frequency range 30 MHz to

1500 MHz

Measurement of EMI Shielding Effectiveness

RESULTS &

DISCUSSION

Surface Resistivity of woven cotton fabric

Pyrrole (%)Surface Resistivity (Ω/)

Polymerization Duration 2 hrs. 3 hrs. 4 hrs.

10 2718 1012 945

20 86 44 33

30 27 17 15

Untreated cotton Pyrrole 10 %

Pyrrole 20 % Pyrrole 30%

Surface Morphology

2 Hours Polymerization

SUBSTRATE MONOMER

DEPOSITED ON 10

GM SUBSTRATE

SURFACE RESISTIVITY

(Ohm/square)

PPY-Coated

Cotton

10 -30% 20 to 2000

PANI- Coated

Cotton

0.1M – 0.3M 1500 - 7000

PPY Coated PC-

Blend

10 – 30 % 50 - 2500

PANI Coated

Polyester

0.1 M 2500

Surface Resistivity of Variable Woven Fabrics

0

20

40

60

80

100

120

140

PP Jute

Su

rfa

ce

Re

sis

tivit

y

(oh

m/s

qu

are

)

Resistivity of Control Nonwoven – 1012 – 1014 ohm/square

Surface Resistivity of Nonwovens

Original PP Original Jute

CP coated PP

Nonwoven

CP coated Jute

Nonwoven

Surface Morphology

CP coated PP

Nonwoven

CP coated Jute

Nonwoven

Cross sectional View

Surface Morphology

0

5

10

15

20

25

PP Jute

EM

I S

E (

dB

)

EMI Shielding Properties of Polymer coated Nonwovens

Sr. No.

Fabric type SurfaceResistivity

(Ω/)

EMI shielding

Grade

1 CP coated Jute

Nonwoven

20 20dB

(30MHz-1.5GHz)

Very Good*

2 CP coated PP

Nonwoven

120 15 dB

(30MHz-1.5 GHz)

Good*

3 CP coated

Woven Cotton

20 30dB

(30MHz-1.5GHz)

Very Good*

CP coated conductive textiles for EMI Shielding

*Suitable for general use:

(Casual wear, office uniform, apron, consumptive electronic products and communication related products.)

Development of Prototypes for specific application:

• Smart textile for occupancy detection (smart mat)

• Smart textile for heat generation (Warming jacket, heating pads)

• Smart textile for Gas Sensing (Ammonia Sensors and Ethanol Sensors)

• Smart textile for Security application

• Smart textile for EMI Shielding.

Indian Patent Filed

Work done at BTRA

•Intruder DetectionHouseholdsCommercial establishmentsSecure areasCarsTheaters

Smart Mat

Smart Textiles

Textiles based SOS systemTextiles based SOS systemTextiles based SOS systemTextiles based SOS system----

Pre-recordedMessage(SOS)

Security ApplicationsSecurity ApplicationsSecurity ApplicationsSecurity Applications

Smart Textiles

Voltage

applied

Increase in current flow,

converted to dissipated heat

Fabric based

heating element

Heat Generation

Up to 45° C

Heating PadsHeating PadsHeating PadsHeating Pads

Thermal BlanketThermal BlanketThermal BlanketThermal Blanket

Heating Pads:• Thermal Therapy – to combat

backaches, muscle & joint pain.

• Reduces sensation by

stimulating thermo receptors.

Electrical thermal

blanket:• High altitude applications.

• Provide warmth and comfort in

cold weather conditions.

• Temperature can be maintained

at 40-450 C.

• Battery operation- 12V, 24V.

Heat Generation

Inclusion of Heating Pads:• Warmth up to 40-42 oC

• Battery operation (12V, 24V)

• Easy handling (detachable)

• Gloves

• Socks

• Shoes

Warmth Providing Jacket

NH3

Cylinder

PPy-cotton

substrate

Gas Detector

Mass flow

controller

mA

Schematic Diagram of Gas detection System

Use of Conductive fabric as Gas Sensors

•Fabric based gas sensors-Polyaniline coated cotton fabrics for ammonia gas sensing

Source- Bhat N.V and co-workers, Textile Research Journal, 2004:74,155

Gas sensing chamber

Gas inlet

Gas outlet

Smart Textiles

* Final stage of acceptance.

Advantages:• Very effective to check the

problem with electrical

activity of patients heart.

•Signal traced are very clear

without using ECG gel.

• No use of metal or any other

corrosive element.

•Very handy and comfortable

to use by patients.

•Disposable and Low in cost.

Fabric based ECG-Electrodes

ICP Coated Textiles : Issues

Advantages

• Tunable conductive textile substrates

• Suitable for most applications

• Ease of Synthesis

• Low cost process

• Retains comfort property

Limitations

• Durability concerns

Measurement of Electrical Surface Resistivity

Four Points probe Resistivity Measurement method

•Voltage drop in the current wires does not contribute error to

the voltage measurement.

•With two probes, the voltage drop from the current flow will not

be separable from the voltage drop in the device under test. It

may be a significant error in low resistance devices.

•Theory used: Vander Paw method.

• Simple polymerization & easy adaptability for large scale.

• Applicable to all kinds of textile substrates.

• Broad range of electrical properties (10 -106 ohm/sqr.) with polymer coatings. Hence useful in variable smart textile applications (pressure sensing, gas sensing) and heat generation applications.

Summary