Smart Textile with Plain Weave Structure Using Hetero-Core Optical Fiber Sens...
Presentation_Elettronica su sustrati tessili_12032014
1. josefsaenz@gmail.com
José Francisco Sáenz C., Ph. D.
Dept. de Ingegneria Elettrica ed Elettronica– Università di Cagliari (Italia)
Fabricating conductive yarns/fabrics
for e-textiles applications
2. • Relatively cheap fibers
• Good mechanical properties
• Obtained from the cultivation of
plants (potentially unlimited
supply)
• Almost never cause allergic
reactions or other dermatological
issues
• Unfortunately: cellulose is
electrically insulating.
Using natural fibers (as cotton) for electronics
3. Using Conductive Polymers (CP)
• They are usually π-conjugated polymers, that can be
easily produced in aqueous solutions.
• After immersion in the polymerisation bath, materials
are coated with an even and uniform layer of CP, and
the presence of doping agents improves the electrical
conductivity of the layer itself.
• Most common types of CP:
• Nitrogen-containing aromatics
• poly(pyrrole)s (PPY)
• polyanilines (PANI)
• Sulfur-containing aromatics
• poly(thiophene)s (PT)
• poly(3,4-ethylenedioxythiophene) (PEDOT)
How to make conductive cotton?
4. • Common textile materials like cotton,
polyester and Lycra are treated with the
conductive polymer PEDOT:PSS,
transforming normally insulating materials
into conductors.
• Conductive textiles can be manufactured into
many shapes, printed, sewn, or knitted into
fabrics, or even woven in fiber forms directly
into textile structures
Mechanical properties of treated and
non-treated cotton yarns
Elongation to
break (%)
Stress at
break (MPa)
Young's modulus
(MPa)
Non treated 6.23 ± 0.98 170.9 ± 7.5 3711 ± 318
PEDOD:PSS+EG
treated 4.58 ± 0.39 69.1 ± 14.6 2987 ± 149
Treating cotton yarns with PEDOT:PSS
5. Cotton-based organic field
effect transistor (OFET)
Cotton-based organic
electrochemical transistor
(OECT)
In the cotton-based OFET the gate electrode is
represented by a conductive yarn; the gate dielectric,
semiconductor and drain/source contacts are deposited
around the yarn.
7. Non-treated
polyester fabric
PEDOT:PSS-
treated polyester
fabric
Conductive fabrics
• It’s possible to treat a wide range of
textile materials including yarns and
fabric made of cotton, polyester,
polyamide, spandex, silk, etc.
• “Low cost” treatment based in the
deposition of a conductive polymer
and other organic solutions in liquid
phase.
• Minimum surface resistance obtained
with a fabric so far (fabric of mix fibers
polyester, viscosa, spandex):
o 15 Ohm/sq
10. Electrode comparison
• Commercial Ag/AgCl ECG electrode
with gel: Standard disposable electrode for
clinical applications
• Sewed Ag-coated Nylon yarn electrode:
State of the art approach for fabricating dry
textile electrodes1
• Conductive polymer treated fabric
electrode: Our proposed solution using
conventional textile fabrics (like cotton,
polyester or polyamide) treated with a
conducting polymer
Commercial ECG
Ag/AgCl with gel
Sewed Ag-coated
Nylon yarn
PEDOT:PSS
treated fabric
By directly treating common textile materials we
obtain very conductive fabrics that, when used as dry
surface electrodes, have shown a performance
comparable to standard gelled-Ag/AgCl electrodes.
Textile bio-electrodes
11. Conductive fabric electrodes with 16cm2 of active area were used to acquire the
ECG signals from a human volunteer at rest and while walking.
For further info: jose.saenz@nano.cnr.it; annalisa@diee.unica.it
Textile bio-electrodes
13. Textile pressure sensors
• An all-textile sensor for measuring the pressure distribution between two
contacting surfaces.
• The force sensing elements consist in a conductive-polymer treated fabric
sandwiched between to two pads of highly conductive yarn sewed on a non
conductive fabric.
Example of the new textile tactile sensor
Non-conductive fabric
Semi-conductive fabric
(Conductive-polymer-
treated textile)
Highly conductive yarn sewed on the
non-conductive fabric
Contact pad
Detail of the sensing elements
14. Textile pressure sensors
• Tactile sensors with square sensing elements of 1cm spaced 3cm
were used for the experiments
• Data is shown for sensors with thin sensing layer (cotton fabric).
16. Summary of applications
• Active electronic devices
o Organic field effect transistors (OFET)
o Organic electrochemical transistors (OECT)
• Biopotential electrodes
o Textile electrodes allow recording biopotentials from the skin surface as for
instance Electrocardiographic (ECG) signals.
• Strain/pressure sensors
o Sensors entirely based on textile materials allow recording pressure or
tension applied on the textile itself with a high sensitivity.
• Electromagnetic interference (EMI) shielding
o This technology allows realizing electromagnetic shields entirely made of
fabric, on large and ultra-large areas.
• Heating textiles
o Patches entirely based on conductive textile materials can be inserted in
garments for providing heating effect with a simple battery.
• Humidity/temperature sensors
• Color changing textiles (electrochromic)
o Conductive textiles can change color from light blue to dark blue using an
electrical signal and be used as displays, indicators or color changing
garments.
