(presentation) smart textiles
TRANSCRIPT
Emerging Technologies Emerging Technologies and Research in Smart and Research in Smart
Textiles Textiles Aylin Hatice Karahan, Pruthesh Vargantwar
Saral kalandhabhatla, Arjun Krishnan, Ravi Shankar
Richard Spontak, John Muth, Tushar K. GhoshNorth Carolina State University
Raleigh, NCItalian Technical Textile and Nonwovens Showcase, Raleigh, 2009
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Context . . . . w Comfortable,w Durable,w Fashionable,w Protective,w Maintainable, etc.
w “Enhanced” Textiles with Additional Functionalitiesn Medical/Therapeutic,n Communication / Computation,n Threat detection,n Others.
w “Enhanced” Textiles with Additional Functionalitiesn Medical/Therapeutic,n Communication / Computation,n Threat detection,n Others.
Smart Textiles
http://www.foster-miller.com
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Smart/Intelligent Textilesw Textile materials or systems that
are able to sense (and sometimes react in response to) an external stimuli (electrical, thermal, chemical, magnetic
or others).w Smart materials have one or more
characteristics that can be dramatically altered.
Smart Textiles
http://www.lord.com/Home/MagnetoRheologicalMRFluid
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Design by Nature . . Really Smart!
w Single cell organisms (slime mold a giant amoeboid cell, species of algae) work autonomously,
w Sensors in the outer layer to detectw Signal processing and interpretationw Reaction (movement, etc.)
Cellular Informatics Lab., Hokkaido University, Japan, http://www.es.hokudai.ac.jp/labo/cell/research_e.html
Smart Textiles
e.g., Fiber-based sensors, (processor),actuators, . .
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Relevant Technologiesw Phase change materials w Shape memory materialsw Chromic materialsw Piezoelectric materialsw Electroactive materials, etc.
w Electronic textiles
Smart Textiles
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Phase Change Materials (PCM)w Materials with high heat of fusion which, melting and
solidifying at certain temperatures, are capable of storing or releasing large amounts of energy.
w Some PCMs change phases within a range that is just above and just below human skin temperature. (Paraffin, Polyethylene glycol [PEG])
w coating fabrics with PCM microcapsules
w extruding PCMs with compatible polymers to produce PCM fibers
http://www.outlast.com
w Applications
n Heating, cooling
Smart Textiles
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Shape Memory Materialsw Shape memory materials
remember their shape or geometry. w After deformation, can regain its
original shape by itself through heating (one-way effect).
Lendlein and Kelch, Angew. Chem. Int. Ed. 2002, 41, 2034-2057
w Applicationsn Insulation (PU film)n Porosity control (diaplex: Mitsubishi)
Smart Textiles
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Chromic Materialsw Chromic materials change their color reversibly
according to external environmental conditions.
w Applicationsn Fashionn Safetyn Camouflage
w photochromic: materials that change color in response to lightw thermochromic: materials that respond to heatw electrochromic: materials that respond to electricityw piezochromic materials that respond to pressurew solvatochromic: materials that respond to the presence of liquidw halochromic: materials that change color when pH changes occur
Smart Textiles
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Electroactive Materialsw Electroactive materials modify their shape upon
application of electric field. wConducting polymerswCarbon nanotubeswDielectric elastomers
Smart Textiles
n Applications
n Artificial muscles
n Actuators
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Piezoelectric Materialsw Piezoelectric materials produce a voltage in response to
an applied force. Similarly, a deformation can be induced by the application of a voltage.
w Have two crystalline configurations. One is organized, while the other is not. Organization of the structure has to do with polarization of the molecules that make up the material.
w Applicationsn Energy harvestingn Actuator
Smart Textiles
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Electronic Textiles
w Level of integration may vary;n Materials level (fibers, dyes, etc.)
n Electronic capabilities designed or fabricated into a textile structure through integration of components. (resistive heaters, quantum tunneling switches, etc.)
n Textile products used as platforms to simply “carry” electronic devices.
w Textile products or systems with “integrated” electronic capabilities that are multifunctional, adaptive and responsivew sense (and sometimes respond to) environmental or other stimuli,
November 12, 2009 Smart Textiles
Products in the Market
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w LifeShirt collects patient data using integrated sensors;n Pulmonary function with
respiratory bandsn Electrocardiography (ECG;
electrical activity of the heart)n Tracks posturen EEG (electroencephalogram)n Skin temp, Blood oxygen leveln Blood pressure
http://www.vivometrics.com
Products in the Marketw Lumalive: Insertable LED
Technology by Phillipsw Enables clothing and
furnishings to have illuminated displays. w LEDS sewn into clothing and
powered by a portable battery pack.
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Source :http://www.lumalive.com
Products in the Marketw 'Thinking Carpet‘
equipped with sensors.w Sensors to measure
pressure, temperature and motion.n Climate control,
n Surveillance,
n Guidance,
http://www.vorwerk-carpet.com
November 12, 2009 14Smart Textiles
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Products in the Marketw Backpack with flexible display
n France Telecom, R & D
Car interior: Tsutani, Japan
November 12, 2009 Smart Textiles
Products in the Market
w Fabric heating pads (Resistive heating)
w Silver loaded fibers are integrated in an undershirt power is supplied by a battery.
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Source: http://www.warmx.de/
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Products in the Market
November 12, 2009 Smart Textiles
w Textile switches using quantum tunneling compositew Becomes electrically
conducting upon pressure
http://www.peratech.com/jacketsbags.php
http://www.fibretronic.com/
Dielectric Elastomer Based Prototype Fiber Actuators
Sohil Arora, Cuneyt Akbay
Long-term Goalw Fabrication of actuators substantially in the
form of textile fibers using electroactive polymers (EAP).
w Requirements are large displacement and moderate to low stress, n Focus on dielectric elastomers.
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Electroactive Polymersw Electroactive polymers (EAP) respond to
external electrical stimulation by displaying a significant shape change. n Ionic: Ionic Polymer Gels, Ionomeric Polymer-Metal Composites (IPMC), Conducting Polymers,
Carbon Nanotubes
n Electronic: Ferroelectric Polymers, Electrostrictive Polymers, Dielectric Polymers
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n Actuatorsn Artificial Musclesn Power harvestingn Many others
n Dielectric elastomers (DE) constitute an imporrtantclass of EAPs
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Motivation: Natural Musclew Natural muscle present in animals
from elephants to butterfliesn Outstanding performance (energy
density)n Soft but strongn Resilient, fracture tolerant, noiselessn Scalable: regardless of the size, the
building block (sarcomere) is the same
w No existing actuator technology compare in overall performance
w If invented can find wide applications including many in textile products
November 12, 2009 Smart Textiles
Actuation Mechanism of DEsw Dielectric elastomers with low elastic modulus
show large actuation strain when subjected to an electrostatic field in a parallel plate capacitor with the dielectric material as the medium.
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• P is the Maxwell pressure
• ε is the relative dielectric constant
• ε0 is the permittivity of free space
• E is the applied electric field
• V is the applied voltage
• z is the film thickness
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Actuator Fiber Prototype
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w Inner electrode : Low viscosity conductor
wDielectric polymer: Silicone/Polyurethane
wOuter electrode : Graphite loaded silicone
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w To control anisotropy
w Axially Strained
w Uniformly Inflated
θ
r
z
/pr tθσ =
/ 2z pr tσ =
Uniaxially Prestrained
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0
2
4
6
8
0 20 40 60 80 100 120
50%100%150%200%250%
Axi
al S
trai
n (%
)
Applied Electric Field (KV/mm)
Silicone
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w Axial Strain up to 7%: Relatively higher strains in silicone
w Radial strain up to 18%: Higher strains in silicone based prototypes
0
5
10
15
20
0 20 40 60 80 100 120
50%100%150%200%250%
Rad
ial S
trai
n (%
)
Applied Electric Field (KV/mm)
Silicone
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Uniformly Prestrainedw Axial actuation strains up to 7.5%w Radial actuation strains up to 7%.
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θ
r
z
/pr tθσ =
/ 2z pr tσ =
Actuation Strain
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w Uniformly prestrained (6.62 psi) silicone
Electrically Actuated Nanostructured Polymer (ENP)
Ravi Shankar, Arjun Krishnan, Pruthesh Vargantwar
ENP: Tri-block-copolymer w If the A endblocks are "hard" (glassy/crystalline) and
the B (a, b, and c) midblock is "soft" (rubbery), then the material behaves as a thermoplastic elastomer (TPE).
n The endblocks behave as physical crosslinks that can be heated into the liquid state.
w If an ABA copolymer is swollen in a B-selective solvent, then the A blocks can micellize to form cross-link sites and, hence, a physical gel.
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a – bridged midblocksb – coronal midblocksc – dangling ends
A A
A
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Mechanical Behavior: Tunable
w Elastic modulus can be controlled through MW and copolymer content.
w Strain energy density tunable
SEB217 SEB161
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Mol. Wt. 217000 g/molSolvent Content- 95 wt. %Electrode –Silver GreasePrestrained (x,y)- (300,300)Break-down field- 18.8 MV/mAreal Actuation- 245%Linear Actuation-85%
Actuation Behavior of ENPsw Tunable electro-mechanical behavior
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w Easy impedence matching
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Fabric Porosity Control: Using Actuator Fibers
w Imagine if the fiber diameters can be changed on demand!
November 12, 2009 Smart Textiles
Composite Print Media for Electronic Textiles
Aylin Karahan, Saral Kalandhabhatla
Long-term Goalw Develop lightweight, conformable sensory
materials that are compatible with electronic textile (E-textile) products including body-worn sensors. n Use screen-printing to deposit an elastic and
conductive nanocomposite layer on fabric to fabricate piezoresistive strain sensors as well as transmission lines.
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Materialsw Polyvinyl chloride (PVC)w Dioctyl sebacate (DOS)
w Plasticizerw Carbon Nanofibers (CNF)w Epoxidised Soybean Oil (ESO)
w Thermal stabilizerw Binder (Binder 2001)
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Polyvinyl Chloride (PVC)
w PVC resins used are Solvin367, 372, and 376 form Solvay Corp.
w Nominal molecular weight of 41, 50, and 60 kg mol–1,
w Particle size of 0.1-3 µm.
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Carbon Nanofiber (CNF)w Vapor-grown CNF obtained from the Showa
Denko Corp. n Fiber diameter: 150 nmn Fiber length: 10 - 20 µm n Aspect ratio: 10 - 500 n Specific surface area: 13 m2/g
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Morphological Characterizationw Good dispersion. The fiber dia range from ca. 150-350 nm. w The PVC particles are seen mostly in clusters and the
individual particle sizes range from ca. 50-700 nm.w Texture of the fracture surface indicates good adhesion
between the particles and the matrix.
X-Sec. Image-1000x(8% CNF 50/50 PVC/DOS)
ó Surface Image-500x(8% CNF 50/50 PVC/DOS)
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ó Surface Image-20000x(8% CNF 50/50 PVC/DOS, printed)
Young’s Modulus
Young’s modulus as function of CNF content for various composites
w Young’s modulus increases significantly from 2.1 Mpa without CNF to 6.9 Mpa with 8% CNF for 50/50 plastisol
w The rise seems to be more rapid beyond percolation threshold of ca. 5wt%
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Secant Modulus
Secant modulus (0-150%) as function of CNF content for various composites
w Significant increase is observed
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Secant modulus (150-250%) as function of CNF content for various composites
w No significant increase is observedw Indicates matrix dominated
finite deformation
Piezoresistive Behaviorw Piezoresistivity describes the dependence of electrical
resistance of a material on applied deformation.w The resistance R of the conductor can be expressed as,
where ρ is the specific resistance or resistivity, L is the length, and A (= wx t) is the cross-section area of the conductor.
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The terms , and represent the geometrical and material components of piezoressitivity
Electrical Behaviorw Higher percolation
threshold for increasing DOS content.
w Percolation threshold ca. 5 wt% for 50/50 composite, slightly higher (6 wt%) for 35/65.
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Printed Fabricw Composite is screen-printed on fabric (Woven;
98% Nylon, 2% Spandex) for further evaluation.
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Electrical Behavior of Printed Fabric
w Printed fabric shows ohmic(linear relationship I-V) character.w No evidence of Joule
heating
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+V-
I
Piezoresistivity of Printed Fabricw Under uniaxial strain
resistance increases.w Gauge factor (G)
w ∆L/L = Strainw ΔR = Change in strain gauge resistancew R = Unstrained resistance of strain gauge
w Calculated Gauge factor is 5.6
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8% CNF 50/50 PVC/DOS (long. direction)
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Questions?Comments?
. . Thanks for your attention
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Areal Actuation Strain of ENPsw The maximum areal
actuation strain goes down with higher co-polymer content
w Dielectric breakdown strength is higher for higher co-polymer content.
w Electro-mechanical coupling factors compare very well other dielectric EAPs.
SEB217 SEB161
November 12, 2009 Smart Textiles
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Uniaxially Prestrained: Blocking Forcew Decrease in blocking force with increased prestrainw Higher blocking force in polyurethane based prototypes
n Higher dielectric constant of polyurethane
0
10
20
30
40
50
60
0 20 40 60 80 100 120 140
50%100%
Blo
ckin
g Fo
rce
(cN
)
Applied Electric Field (KV/m)
Polyurethane
November 12, 2009 Smart Textiles
Dioctyl Sebacate (DOS)w Dioctyl sebacate (DOS) manufactured by
Acros Organics with the molecular weight of 426.68 g mol-1 and density of 0.910 g/cm3
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Ritchie, P. D., Plasticizers, Stabilizers, and Fillers, Plastics Institue, London ILIFFE Books Ltd., 1972
Other Additives (ESO and Binder)w Epoxidised Soybean Oil (ESO) as a thermal
stabilizer and used as obtained from Spectrum Chemical Mfg Corp. n ESO does not affect viscosity of the plastisol.
w Binder 2001 (a member of Aromatic Polyisocyanatefamily), obtained from Nazdar SourceOne, is one of the common binders used for plastisol printing of polyester, polyamide or aramid fibres.
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Sample Preparation
DOS + ESO [Mix 60 sec.]
Add CNF & PVC [Mix 60 sec.]
Add Binder [Mix 60 sec.]
Composite for Printing
w Preparation of the plastisol composite was carriedout in three steps.
w Mixing was carried out in a high-shearplanetary mixer (Mazerustar KK-50S)
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Composite Film Composition
w Composites with four levels of PVC/DOS ratios (50/50, 45/55, 40/60, 35/65), and eight levels of CNF concentrations from 0 up to 10 wt% are prepared.
w The composite was compression molded into 0.7-1 mm thick films under static load at 160°C for 30 min.
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Morphological Characterizationw SEM studies of film
surfaces and cryofracturedsurfacesw Specimens, coated with 12-
13 nm of gold were examined in a field emission scanning electron microscope (FESEM: JEOL 6400F).
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Electrical Behavior: Measurementw Four-point probe using set-up
consisting of a current source (Keithley 6221) and a nano-voltmeter (Keithley 2182A).
w Electrometer (Keithley 6517B and Model 8009 Resistivity Test Fixture) for high-resistance.
w For piezoresistive behavior strip-like specimens, 50mm long and 25mm wide were used.
w The test sample was deformed at a strain rate of 0.02 min-1.
November 12, 2009 53Smart Textiles