Vapours and Aerosols of Bitumen - exposures and classification
Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 Integrated Optical Microsensors Based On Porous...
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Transcript of Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 Integrated Optical Microsensors Based On Porous...
Ischia, 21-23 giugno 2006Riunione Annuale GE 2006
Integrated Optical Microsensors Integrated Optical Microsensors
Based On Porous Silicon Based On Porous Silicon
Technology For Vapours And Technology For Vapours And
Liquids IdentificationLiquids IdentificationL. Rotiroti, I. Rea, D. Alfieri, I. Rendina and L. De Stefano
Institute for Microelectronic and Microsystem – Dept. of Naples,National Council of Research, Naples, Italy
L. Moretti, F.G. Della CorteDIMET – “Mediterranea” University of Reggio Calabria,
Reggio Calabria, Italy
Ischia, 21-23 giugno 2006Riunione Annuale GE 2006
• …is a low-cost material and fabrication process;
• …has a large specific surface area (~ 200 m2/cm3);
• …rapidly and effectively interacts with chemical species;
• …shows evident changes in several physical properties usable for sensing (reflectivity, photoluminescence, electrical conductivity, optical waveguiding...);
• …easy to integrate in hybrid systems (MEMS, MOEMS, TAS, Labo-on-Chip etc...);
• ...compatible with microelectronic technologies;
• …its surface can be chemically modified to enhance analyte selectivity.
The transducer element: PSiThe transducer element: PSi
Si p+ type
DBR # 1
DBR # 2
8.3 m
600 800 1000 1200 1400 1600
0.2
0.4
0.6
0.8
1.0
Re
flect
ivity
(a
.u)
Wavelength (nm)
monolayer
800 1000 1200 1400
0.0
0.5
1.0
1.5
2.0 microcavità ottica
Ref
lect
ivity
(a.
u)
Wavelength (nm)
Ischia, 21-23 giugno 2006Riunione Annuale GE 2006
PSi Layer
Carrier out
Carrier in
Analyte
Pneumatic actuator
A step furtherA step further
Ischia, 21-23 giugno 2006Riunione Annuale GE 2006
Silicon-glass anodic bondingSilicon-glass anodic bonding
Anodic Bonding is a bonding process of a silicon wafer to glass under the influence of high temperature and an externally applied electric field
@ 200°CElectric Field 2500 V
Planar ElectrodeBonding time 5 min
Ischia, 21-23 giugno 2006Riunione Annuale GE 2006
Flow Injection AnalysisFlow Injection Analysis
Ischia, 21-23 giugno 2006Riunione Annuale GE 2006
Experimental results-1Experimental results-1
-chamber volume: 4 -chamber volume: 4 llPSi layer thickness: 2 PSi layer thickness: 2 mm
0.0 0.5 1.0 1.5 2.0 2.50.0
0.2
0.4
0.6
0.8
1.0
1.2 Carrier burst PSi signal
Tresp
= 156 ms
Trec
= 24 ms
On exposure to Isopropanol
Re
fle
cti
vit
y (
a.u
.)
Time (sec)
-chamber volume: 12 -chamber volume: 12 llPSi layer thickness: 6 PSi layer thickness: 6 mm
0 2 4 6 8 100.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
Re
fle
cti
vit
y (
a.u
.)
Time (s)
Carrier burst PSi signal
Response time = 450 ms
Ischia, 21-23 giugno 2006Riunione Annuale GE 2006
VOC Isopropanol Ethanol Methanol
Response time
156 ms 104 ms 64 ms
Recovery time
24 ms 55 ms 48 ms
Experimental results-2Experimental results-2
Comparison between response times due to different substances.
All the measurements have been made in saturated atmosphere
Ischia, 21-23 giugno 2006Riunione Annuale GE 2006
The second device schemeThe second device scheme
The planar waveguide is realised by thermal oxidation of a SOI wafer, in a dry atmosphere at 1050 °C: a thin silicon oxide layer of 100 nm confines the light into a 3 μm thick crystalline silicon layer. The transduction element of this sensing device is fabricated by a two-step electrochemical etching process of a <100> silicon wafer, p+ type, with a resistivity of 8-12 mΩcm, using an HF/EtOH (50:50) solution. The elements are joined together by AB technique.
Ischia, 21-23 giugno 2006Riunione Annuale GE 2006
Experimental set-up and resultsExperimental set-up and results
An infrared laser (=1550nm) is coupled into the SOI waveguide through an optical fiber. The trasmission beam is collected by another optical fiber and directed in a photodiode.
0 50 100 150 200 250 3001.0
1.5
2.0
2.5
3.0
3.5
Inte
ns
ity
(m
V)
Time (sec)
Ischia, 21-23 giugno 2006Riunione Annuale GE 2006
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