Sensori chimici in fibra ottica basati su nanotubi di carbonio

Optoelectronic Division - Engineering Department
University of Sannio, Benevento – Italy
Sensori Chimici in Fibra Ottica
basati su Nanotubi di Carbonio
M. Consales1, M. Pisco1, S.Campopiano2, A. Cutolo1, M. Penza3, P. Aversa3,
M. Giordano4, A. Cusano1
POSTER # A27
(1): University of Sannio,
Optoelectronic Division Engineering
Department,
Benevento - Italy.
(3): ENEA, Materials and
New
Technologies,
CR
Brindisi, Brindisi - Italy.
Riunione Annuale GE 2006
(2):
Department
for
Technologies, University
Parthenope, Napoli, Italy
(4): Institute for Composite
and Biomedical Materials,
CNR, Napoli, Italy.
Ischia, 21-23 giugno 2006
Optoelectronic Division - Engineering Department
University of Sannio, Benevento – Italy
Silica Optical Fiber (SOF) Sensors
For an important number of environmental monitoring and industrial
applications fiber-optic sensor technology offers several advantages for significant
metrological improvement through:
High sensitivity
Immunity to electromagnetic interference
Safety in the corrosive environments
Fast response
This technology is suitable for distributed measurements and it is, by definition,
compatible with the fiber-optic communication networks
The scientific community is interested in:
New devices able to provide high performance sensing mechanism and
multiplexing capability.
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Optoelectronic Division - Engineering Department
University of Sannio, Benevento – Italy
Principle of Operation
ΔRfilm=f ( ΔεFilm , ΔdFilm)
Single-mode optical fiber
SWCNTs sensitive layer
Pinc
Pref
•Rfilm is the fiber-film reflectance
•εSWCNTs= ε1+jε2 is the dielectric constant of
the film
• dSWCNTs is the film thickness
When the optical probe is exposed to a target analyte, its molecules are
adsorbed within the sensitive layer, changing its thickness and
complex dielectric function and thus the optical signal reflected at the
fiber film interface.
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Optoelectronic Division - Engineering Department
University of Sannio, Benevento – Italy
Why Single-Walled Carbon Nanotubes (SWCNTs)?
Carbon nanotubes are
basically sheets of graphite
rolled up into a tube to form a
cylinder.
• Peculiar hollow structure
• Diameters in the range 1-10 nm
• High specific surface area (100-1800 m2/g)
• Particular interactions between carbon
atoms and gas molecules
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Optoelectronic Division - Engineering Department
University of Sannio, Benevento – Italy
Langmuir-Blodgett (LB) deposition technique
HiPco SWCNTs (purchased by CNI) films have been deposited
monolayer by monolayer by successively dipping the substrates up and
down through the monolayer
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Optoelectronic Division - Engineering Department
University of Sannio, Benevento – Italy
Structural and morphological CNTs characterization
SEM image of SWCNTs bundles
XRD from SWCNTs powder
•Mean rope diameter: 1-40 nm
• Mean rope length: 2-15 µm
• Monolayers spacing ~ 2.0 nm
HRTEM image of SWCNTs bundles
Low magnification
Riunione Annuale GE 2006
HRTEM image of SWCNTs bundles
High magnification
Ischia, 21-23 giugno 2006
Optoelectronic Division - Engineering Department
University of Sannio, Benevento – Italy
Volatile Organic Compounds (VOCs) detection
Standard Silica Optical Fiber coated by 4 monolayers of SWCNTs (approx. 8nm)
0.80
TOLUENE
Optoelectronic Signal
93 ppm
TOLUENE VAPORS
73 ppm
0.79
64 ppm
54 ppm
Resolution of approx. 290 ppb
0.78
0.77
Response times (10%-90%) of approx. 9 minutes
0.76
120
180
240
300
360
Time (min)
Recovery times (90%-10%) of approx. 5 minutes
Optoelectronic Signal (A.U.)
0.800
0.795
39 ppm
XYLENE
27 ppm
0.790
XYLENE VAPORS
22 ppm
17 ppm
0.785
7 ppm
0.780
3 ppm
0.775
Resolution of approx. 120 ppb
0.770
0.765
120
180
240
300
360
420
480
Response times (10%-90%) of approx. 11 minutes
Time (min)
Recovery times (90%-10%) of approx. 6 minutes
Response of a Carbon Nanotubes based SOF sensor to different
concentrations of (a) toluene and (b) xylene vapors, at room
temperature.
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Optoelectronic Division - Engineering Department
University of Sannio, Benevento – Italy
HOF coated by 20 monolayers of
SWCNTs for TetraHydroFuran
(THF) vapors detection
Optoelectronic Signal (A.U.)
Hollow-core Optical Fibers (HOFs) based chemical
sensors
TetraHydroFuran
2.589
2.586
184 ppm
2.583
200 ppm
291 ppm
2.580
180
240
300
360
Time (min)
Images of a photonic band-gap optical
fiber without and with SWCNTs
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Response of the photonic band-gap fiber based sensor
to three decreasing concentration of THF vapors, at
room temperature.
Ischia, 21-23 giugno 2006
Optoelectronic Division - Engineering Department
University of Sannio, Benevento – Italy
Hydrogen Detection at Criogenic Temperatures
Hydrogen on at lower concentration
0.494
Optical response (A.U.)
0.493
Hydrogen on
0.492
0.491
0.490
Hydrogen off
0.489
0.488
0.487
Hydrogen off
0.486
T=-160°C
0.485
120
140
160
180
200
220
240
260
Time (min)
Response of a Carbon Nanotubes based optical fiber
sensor to two different concentration of gaseous
hydrogen, at -160°C.
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Optoelectronic Division - Engineering Department
University of Sannio, Benevento – Italy
THANKS FOR YOUR
ATTENTION
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006