fiber optic sensing: principle & developments fibers... · 2018. 1. 4. · interference between...
TRANSCRIPT
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Dr. Umesh TiwariScientist
V-4 (PHOTONICS)
E.mail: [email protected]
CSIR-CSIO, SECTOR 30, CHANDIGARH - 160 030
Fiber Optic Sensing: Principle & Developments
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OUTLINE
FIBER OPTIC SENSOR BASICS
MODULATION MECHANISMS
TYPICAL FO SENSOR SYSTEMS
FOS TECHNOLOGY AT CSIO
CURRENT TRENDS AND FUTURE SCENARIO
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Optical Fiber Sensor
Optical fiber sensor: A sensor that measures a physical quantity based on its modulation on the intensity, spectrum, phase, or polarization of light traveling through an optical fiber.
Compact size Multi-functional Remote accessibleMultiplexingResistant to harsh environmentImmunity to electro-magnetic interference
Advantages of optical fiber sensors
PresenterPresentation NotesTwo types of optical fibers (single mode for long haul transmission and multimode for short-distance transmission)Fiber configuration:Core: made of Ge-doped silica. 8um core diameter for single mode, 50/100um core diameter for multimodeCladding: pure silica. 125um in diameterBuffer/coating: polymer. 250um in diameterJacket: plastic for protection
Transmit light by total internal reflection
Optical transmission (light source, focus lens, optical fiber, photodetector)
Light can be characterized by: intensity (how bright the light is), wavelength (the color of the light), pulse width (for pulsed light)
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OPTICAL SENSORS (CONVENTIONAL)
BULK OPTICAL COMPONENTS AND LIGHT SOURCES (GAS LASERS, HALOGEN LAMP ETC.)
PROBLEMS:
PORTABILITYREMOTE MONITORING COST RUGGEDNESSEFFICIENCY
SOLUTION EMERGED THROUGH OPTICAL FIBERS & OE OMPONENTS FOR SENSING e.g. FO SENSORS
LIMITED USE
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FIBER OPTIC SENSORS: WHY?LARGE BANDWIDTH
EFFICIENT TRANSMISSION (LOW LOSS)
IMMUNITY TO EMI/ RFI/ EMP
SECURITY OF INFORMATION
GEOMETRIC VERSATILITY
SMALL SIZE AND LIGHTWEIGHT
FLEXIBILITY
RESISTANT TO HOSTILE ENVIRONMNT
FREEDOM FROM CROSS-TALKS
NO SPARKING AND FIRE HAZARDS
SINGLE FIBER SERVES BOTH AS SENSOR AND DATA TRANSMITTING CHANNEL
MULTIPLEXING & SPATIALLY DISTRIBUTED SENSING
HIGH PERFORMANCE
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CLASSIFICATION
EXTRINSIC SENSORS
INTRINSIC SENSORS
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EXTRINSIC SENSORS
Where the light leaves the transmitting fiber to be changed before it continues to the detector by means of the return or receiving fiber.
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INTRINSIC SENSORS
Intrinsic sensors are different in that the light beam does not leave the optical fiber but is changed whilst still contained within it.
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Optical Fiber Sensor TypesOptical Fiber Sensor Types
Point sensor: detect measurand variation only in the vicinity of the sensor
Multiplexed sensor:Multiple localized sensors are placed at intervals along the fiber length.
Distributed sensor:Sensing is distributed along the length of the fiber
Opto- electronics
Output, M(t, Zi )
Opto- electronics
Output, M(t,z)
Opto- electronics Sensing
elementOutput, M(t)
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LIGHT WAVE PARAMETERS
1. Amplitude / Intensity
2. Phase
3. Wavelength
4. Polarisation
5. Time / Frequency
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1. PHASEPhysical Mechanism
Interference between signal and reference fibers (Mach- Zehnder monomode system) or different propagation modes in multimode fiber
Detection CircuitryFringe counting, or fractional phase-shift detection
Main Limitations- Laser noise and stability- Measurement of small phase shifts- Elimination of unwanted spurious effects (other physical variables)
Typical Examples- Fiber Gyroscope and Hydrophone- Multimode Gage for Dynamic Pressure/Strain Measurement
OPTICAL MODULATION AND DETECTION TECHNIQUES
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2. INTENSITYPhysical Mechanism
Modulation of transmitted light by absorption, emission or refractive index changes
Detection CircuitryAnalog (or digital for go/on-go transducers)
Main Limitations
Normalisation for source intensity variations and, variable line and connector losses (at long distances)
Typical Examples
- Strain/ Pressure Gage using Modulated Microbending Loss- Optical Encoders
OPTICAL MODULATION AND DETECTION TECHNIQUES
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3. WAVELENGTHPhysical Mechanism
Spectral-dependant Variations of Absorption, Emission and Refractive Index
Detection CircuitryAmplitude Comparison at two Fixed Wavelengths, or Analogue Signal for Scanned Wavelength
Main Limitations- Suitable Scanned Wavelength Sources - Wavelength Dependant Line Loss
Typical ExamplesTemperature Measurement By:
- Variable Fabry-Perot Cavity- Birefringent Crystal- Semiconductor Band Gap Shift
OPTICAL MODULATION AND DETECTION TECHNIQUES
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INTENSITY MODULATED SENSORS
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Quasi-Distributed Sensing
• Fiber Bragg Grating (FBG)• Strain, Temperature, Pressure, Load
OTDR
Measurand field M(z,t)
M(zj ,t)
z
M(t) Fiber
Sensitized regions
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FO INTERFEROMETRIC SENSORS
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SENSORS FOR SMART STRUCTURES AND SKINS (BASIC SENSORS)
Extrinsic Fabry Perot Interferometer (EFPI)
Fiber Bragg Gratings (FBGs)
Long Period Gratings (LPGs)
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EXTRINSIC FABRY PEROT INTERFEROMETRIC (EFPI) SENSOR
Variation of Output Intensity (in Arbitrary Units) with Change in Gap Separation `S’ (µm)
Schematic of EFPI Sensor
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HIGH RESOLUTION WELL-LOCALISED SENSING REGIONABSOLUTE MEASUREMENTLINEAR OUTPUTINSENSITIVE TO OPTICAL SYSTEM INTENSITY FLUCTUATIONSCAPABILITY TO MULTIPLEX SEVERAL SENSORS ALONG ONE FIBERCOST-EFFECTIVE
FIBER GRATING SENSORS : ADVANTAGES
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λB = 2neff Λ
(Bragg Condition)
λB :Bragg wavelength, neff. :Effective RI of the core ,
Λ:Grating pitch
Fiber Bragg Grating (FBG)
( ) ( ) TpeB
B Δ++Δ−=Δ αξελλ 1
Effective Photo-elastic coeffep =ε = Deformation ( )με
ξ = Thermo-optic coeffα = Thermal expansion coeff
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Fiber Bragg Gratings
• The grating parameters – Length of grating – Strength of grating– Refractive index.manipulated to produce desired grating characteristics
• The different types of FBGs are – Chirped FBGS– Blazed/Tilted FBGs– Phase shifted FBGs– Long-Period In-Fiber FBGs
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FBG SensorsWith more details, if the period of refraction changes due to an external strain ε
and/or a temperature
variation ΔT, the Bragg wavelength changes according to the law:
April 19th 2013
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Normalize strain response at
constant temperature
Normalize thermal response at
constant strain
Sensing Principle of FBG
23
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2. Tuneable laser interrogation unit
illuminates fiber and measures reflected
Bragg wavelengths
1. Numerous sensors recorded on a single fiber, mm or km apart.
Sensors can measure strain, pressure, temperature etc
3. Processing Unit converts
wavelengths to measurands
of
interest, which are displayed real time
or logged for future analysis
Fiber
Data
FBG Sensors
A Fiber Bragg Grating Sensing System
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FBGs - FEATURES
LENGTH: 5 - 50 mm, PITCH (Λ) : 0.5 - 1 µm (TYPICAL)
STRONGEST INTERACTION or MODE COUPLING OCCURS AT BRAGG WAVELENGTH (λB )
WAVELENGTH CODED INFORMATION – SELF REFERENCING FEATURE (e.g ABSOLUTE SENSORS)
BASIC SENSING IS THROUGH GENERATION OF STRAIN – GENRIC SENSORS
SENSITIVITY TO STRAIN, TEMPERATURE AS GOOD AS OF FIBER INTERFEROMETERS
EASE OF MULTIPLEXING & DISTRIBUTED SENSING
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Long Period Grating (LPG)
λi = [n01 - n(i)clad ] Λ
λi : Loss resonance wavelength coupled to the ith cladding mode
n01: : Effective index of core mode, n(i)clad : Effective index of the ith
cladding mode
(Phase Matching Condition)
A M Vengsarkar & V Bhatia 1995
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COUPLES LIGHT FROM THE GUIDED CORE MODE INTO CLADDING MODES IN BANDS CENTRED AT λіLength: 10 - 50 mm, Pitch: 100 – 600 μm (TYPICAL)
FUNCTION AS WAVELENGTH DEPENDENT LOSS ELEMENTS
ANY VARIATION IN STRAIN, TEMPERATURE OR EXTERNAL R.I. CAN CAUSE LARGE WAVELENGTH SHIFTS IN LOSS RESONANCES
CONCENTRATION MEASUREMENT OF ANALYTES, LIQUIDS AND BIO ORGANISMS (PROCESS CONTROL and BIOTECH INDUSTRY)
SIMULTANEOUS MEASUREMENT OF MULTIPLE PARAMETERS
LPGs: FEATURES
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FBG/LPG WRITING SYSTEM LAYOUT
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Integrated Vehicle Health Monitoring (IVHM) for Aerospace Vehicles
X-33 is a half scale sub-orbital experimental flight test vehicle- a collaborative effort between NASA & Lockheed Martin
X-33 Vehicle Sensor Suite Involves:
Objectives: To provide an automated collection and paperless health decisions, maintenance and logistics systems
Greater need to reduce excessive cost associated with access to space
Focus on providing easy repair access for simplified servicing of infrastructures and expedited decision making from detected faults and anomalies
X-33 Advanced Technology Demonstrator
Distributed strain sensor (FBGs)Distributed Hydrogen Sensing (FBGs)Distributed Temperature Sensing (Raman OTDR)
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FOS Technology Developments at CSIO
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FBGFBG--LPG Writing SystemLPG Writing System
FBG Sensor applications: Force, pressure, strain/stress, displacement, temperature, acceleration, vibration, acoustics, Chemical and biological sensing, Electrical and magnetic measurements
Grating Writing Modes
1. Phase Mask (Static & Scanning)
2. Interferometric
3. Point-by-Point
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• KrF Excimer Laser (248 nm) with LN module• UV beam conditioning and manipulating optics • Automated mask and fiber holder• Proximity phase mask • Optical diagnostic and feedback unit with all operation through computer
• Fiber and phase mask positioning and alignment systems• CCD camera based viewing system for monitoring and controlling mask to fiber relative position
• Fiber tension monitoring assembly • Provision for monitoring and display of the writing beam • OSA on-line monitoring of the grating inscription process• Computer control and software for the writing system
FBG/LPG Writing SystemFeatures:
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FBG BASED PETROL LEAK SENSOR
1549.35
1549.4
1549.45
1549.5
1549.55
1549.6
1549.65
0 5 10 15 20Time (min)
Bra
gg w
avel
engt
h (n
m)
Dipping Drying Ph
cCurrent Science, 90(2), p 219-221, 2006
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Design, development and Packaging of FBG sensors for structural Health Monitoring
0
50
100
150
200
250
300
350
-500-400-300-200-1000
Micro Strain
Load
in k
N
Strain Gage (Average)FBG (Average)
0 5 10 15 20 25 30-100
0
100
200
300
400
500
600
700
800
Com
pres
sive
Stra
in (μ
ε)Applied Load (Tonne)
FBG1 SG1 FBG2 SG2 FBG3 SG3
0 500 1000 1500 2000
0
100
200
300
400
500
600
700
Tens
ile S
train
(με)
Applied Load (Kg)
CSIO FBG ESG1 Micronoptics FBG ESG2
Current Sciences, 97, pp. 1539-42, 2009
MS Specimen
Concrete Specimen
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Strain Guage
Interrogator Unit
Weldable Packaged FBG
1544.5 1545.0 1545.5 1546.0 1546.5
-70
-60
-50
-40
-30
Ref
lect
ed P
ower
(dB
m)
Wavelength (nm)
Precured FBG Sensor Postcured packaged FBG Sensor
Pre-cured and post-cured reflection spectrum of packaged FBG sensor
λB = 1545.54 nm and a grating length of 10 mm FWHM of the FBG was 0.141 nm
Comparison of the strain response of Comparison of the strain response of packaged and unpackaged FBGpackaged and unpackaged FBG
Presented at ICC-CFT, IISc Bangalore-2011
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Weldable Packaged FBGs for Structures
Mild Steel Specimen
Hysterisis Plot
Temperature response of Packaged FBG
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Embeddable Packaged FBGs for Structures
0
50
100
150
200
250
300
-500-450-400-350-300-250-200-150-100-500
Micro strain
Load
in k
N
FBGSG
Concrete Specimen
Comparison between Packaged FBG Sensors with ESGs under
Compressive Loading
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Field Study of Metallic Bridge in Himachal Pradesh with NIT Hamirpur & HPPWD
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3D design and photograph of fabricated FBG packaging fixture
Result of the FE Analysis for FBG packaging fixture
FBG Packaging
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Photograph of the packaged FBG sensor for cementitious mounting
0 20 40 60 80 1000
20
40
60
80
100
120 Calibration Factor 1.3 pm/με
Shift
in W
avel
engt
h (p
m)
Measured Strain (με)
0100200300400500600700800900
25 35 45 55 65
Applied Temperature ˚C
FBG W
avelen
gth Shift in
pm
Strain and temperature calibration plot
Results
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BEAM TESTING IN THE LAB USING PACKAGED FBG SENSORS
FBG4 (λ4 )FBG2
(λ2 )FBG3 (λ3 )FBG1 (λ1 )
Roller end Rocker end
BeamLoad
A View of FBG sensors installed on the RC beam in Lab
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Comparison of response of FBG sensor and ESG sensor on RC
beam
0
0.05
0.1
0.15
0.2
0.25
0.3
0 20 40 60 80 100 120 140 160
Applied load (KN)
Wavelen
gth shift (n
m) Δʎ1 (nm)
Δʎ2 (nm)Δʎ3 (nm)Δʎ4 (nm)
Response of FBG sensors at different locations on RC beam
Results
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FIELD STUDIES OF FBG SENSORS
FBG=1544nm FBG=1541nm (with Tag)
FBG=1548 nm
FBG=1556nm
RAILWAY LINE
DELHIBridge Layout with FBG
sensors installed
0.0 0.5 1.0 1.5 2.0 2.5 3.0-3-2-10123456789
1011 Response of packaged FBG (1548 nm) near the pillar
Δλ
(pm
)
Time (Sec.)
MBIU+ Loaded truck 1 MBIU+ Light vehicle MBIU+ Loaded truck 2 MBIU only MBIU static
Various Sensors with FBG sensor on the Girder of the bridge and response of FBG sensor for different loading under bridge running condition
(19.03.14 – 21.03.14)
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FBG1-1539.967 FBG2-1545.644 FBG3-1542.122
FBG7- 1555.223 FBG8-1558.712
FBG9-1559.012
FBG10-1537.985
TO DELHI TO HAPUR
FBG4-1548.751 FBG5-1538.791 FBG6-1545.046
RAILWAY LINE
FIELD STUDIES OF FBG SENSORS (23.04.14 – 25.04.14)
1454 1444
TO DELHI TO HAPUR
1090 1440 x
RAILWAY LINE
1462
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Photograph of the close view of the mounted FBG and other
conventional sensors
Photograph of the test site of Girder Bridge near Hapur
Test Site
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FBG 8‐1558.712Strain during a vehicle movement
‐2.000
0.000
2.000
4.000
6.000
8.000
10.000
12.000
0 20 40 60 80 100 120
Samples Recorded
Strain (µ
ε)
Results
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FBG3‐1542.122Strain during a vehicle movement
‐10
0
10
20
30
40
50
0 20 40 60 80 100 120 140 160 180
Samples Recorded
Strain (µ
ε)
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FBG5‐1538.791Strain during a vehicle movement
‐5.000
0.000
5.000
10.000
15.000
20.000
0 20 40 60 80 100 120 140 160 180
Samples Recorded
Strain (µ
ε)
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FBG Sensors Technology for Energy SectorHot Spot Detection and Location in Transformer
Presented at ICOP -2009
FBG installed in 25 kVA Live Transformer at Vadodara since Sep.,2009
In Collaboration with ERDA, M/s Alstom, Vadodara and M/s Ardison, Mohali
DIT Sponsored Project
Wdg temp. using FBG
Top oil temp. using FBG Top oil temp. using TC
% Loading of Transformer
Ambient Temp. using TC
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FBG Based Technique for Monitoring Demineralization of Bone (Bio-Mechanics Application)
0 2 4 6 8 10
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0
200
400
600
800
1000
1200
1400
Stra
in G
radi
entB
1 (μ
ε/kg
)Cumulative Ca Loss (gm)
Decalcified Bone Untreated Bone
0
20
40
60
80
100
120
140
Strain Gradient B
2 (με/kg)
Time (Days)
Comparison of strain response of normal and decalcified bone
Experimental Setup
Results and Discussion
•Same load produced almost double strain in the demineralized sample as compared to that in untreated sample •Calcium loss of even 0.3906 gm (treatment 1) resulted in 1.3 times/ 24% more strain for same load and a calcium loss of 1 gm resulted in 50% increase in strain. As the calcium loss was more than 2 gm the strain increase was close to 300%
Orthopaedics and Traumatology: Surgery and Research (Accepted)
Presented at ISMOT - 2009
In consultation with Orthopedic Experts from PGIMER, Chandigarh
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Impact absorption capability of a mouth guard using FBG sensors
Experimental Setup
Cricket ball impact on mouthguard and Jaw model using FBG Sensor
Impact absorption capability of custom-made mouthguard investigated utilizing FBG sensors in distributed manner
The impact absorption capability was found to be more than 90% for the center impact
This study will be useful for better designing of custom-made mouthguards
Ref: Tiwari et al. Dental Traumatology (2011)
1551.0 1551.5 1552.0 1552.5-55-50-45-40-35-30-25
Reference for 30 degree Impact for 30 degree Reference for 45 degree Impact for 45 degree Reference for 60 degree Impact for 60 degree
Ref
lect
ed P
ower
(dB
m)
Wavelength (nm)
1553.6 1554.4 1555.2 1556.0-55-50-45-40-35-30-25-20
Ref
lect
ed P
ower
(dB
m)
Wavelength (nm)
Reference for 30 degree Impact for 30 degree Reference for 45 degree Impact for 45 degree Reference for 60 degree Impact for 60 degree
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Long Period Grating Based Humidity Sensor
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LPFG Based Humidity Sensing
COBALT CHLORIDE/GELATINE
BASED
HYGROSCOPIC COATING
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Sensing Probe Fabrication and Characterization
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FE-SEM NSOM
RI=1.34146 nsur
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Results
1510 1520 1530 1540 1550 1560-77
-76
-75
-74
-73
-72
-71
-70
Tran
smitt
ed P
ower
(dB
m)
Resonant wavelength (nm)
Air (Reference) 35% RH 45% RH 55% RH 65% RH 75% RH 85% RH 90% RH
The spectral signature of coated LPFG at different levels of known RH
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Results
Hysteresis plot of coated LPFG w. r. t. various levels of RH
Hysteresis
calculation wrt increasing RH values
± 0.2%
Hysteresis
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Results
Response at 70% RH level for 300
minutesStability
error 0.06%
Stability plot
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LPG based Biosensor
1350 1400 1450 1500 1550 1600 1650-80-78-76-74-72-70-68-66-64-62
Tran
smitt
ed P
ower
(dB
m)
Wavelength (nm)
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STRUCTURE OF A BIO-SENSOR
• BIORECOGNITION ELEMENT : Biomolecules
(enzymes, micro-
organisms, strand of DNA) produced by interaction of an analyte
with an interface.
• INTERFACE : Surface of transducer with immobilized bioelements.
• TRANSDUCING ELEMENTS : Electrochemical,acoustic,piezo- electrical, optical etc.
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Biosensor
= biorecognation molecule/bioreceptor
+ Transducer
EnzymeAntibodyMembranesOrganellesCellsTissuesCofactorsDNAPeptideMicroorganism
• Electrochemical – Amperometric– Potentiometric– Conductiometric• Piezo-electric• Calorimetric• Acoustic• Optical
ReceptorsTransducers
PhysicalChemical
•Transformation•Coupling
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Preliminary Investigation on Long Period Grating based bio-sensor
Reference Protein
GlucaldihideAB
SilanizationGlutaraldehydetreatment
Protein A treatmentAntibody immobilization
SEM images of LPG surface after chemical processing
Shift in wavelength for different bio-agent binding
Presented at ISMOT - 2009
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1520 1540 1560 1580 1600 1620 1640 1660-77
-76
-75
-74
-73
-72
-71
-70
Tx (d
Bm
)
Wavelength (nm)
H2So4 APTES GOx 10mg/3ml Glu15 mg/10ml
1520 1540 1560 1580 1600 1620 1640 1660
-76
-75
-74
-73
-72
-71
-70
-69
Tran
smitt
ance
(dB
m)
Wavelength (nm)
H2So4 APTES GOx 10 mg/3ml Glu 20 mg/10ml
Effective Wavelength Shift = 2.52nm Effective Wavelength Shift = 2.68nm
1520 1540 1560 1580 1600 1620 1640 1660-77
-76
-75
-74
-73
-72
-71
-70
Tran
smitt
ance
(dB
m)
Wavelength (nm)
H2So4 APTES GOx 15 mg/3ml Glu 30 mg/10ml
Effective Wavelength Shift = 2.88nm
LPG Sensor based on CoLPG Sensor based on Co--valentvalent Binding Binding Technique for Glucose DetectionTechnique for Glucose Detection
Ref: Deep
A. and
U. Tiwari
et al. Biosensors
and
Bioelectronics
(2012)
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Long Period Grating based Sensor for Urea Detection
-
Sodium Bicarbonate
Pure Milk
Urea(toxic)
Glucose
starch
Vegetable oil
Salts
Milk Adulteration• Parameters affected are FAT and SNF content in MILK• Minimum content of FAT – 3.5%• Minimum content of SNF – 9%
-
COATING OF APTES/ENZYME ON LPFG
HF acid treatment Piranha
solution treatment
OH
OH
APTES
O
O
Si (CH2)3 NH2
COOH
Ureaseenzyme
Optical Fiber
LPFG Based Urea Sensing
-
Bare Fiber APTES treated Fiber Urease treated Fiber
FESEM image of the treated and untreated optical fiber
-
Normal Fiber
Normal Fiber
Urease treated Fiber
CLSM Image of Urease treated fiber and untreated Fiber
-
APTES treated Fiber
Urease treated Fiber
Fluorescence Comparison between APTES treated and UREASE treated
Fiber
-
Experimental Setup
-
Results
1580 1600 1620 1640 1660
-76
-75
-74
-73
-72
-71
-70
Tra
nsm
itted
Pow
er (d
Bm
)
Wavelength (nm)
10 mg/ml 20 mg/ml 30 mg/ml 40 mg/ml
1580 1600 1620 1640 1660
-77
-76
-75
-74
-73
-72
-71
-70
Tran
smitt
ed P
ower
(dB
m)
Wavelength (nm)
Pure Milk 10mg/ml Urea 20mg/ml Urea 30mg/ml Urea 40mg/ml Urea
Measured transmission spectrum
Untreated LPG for Pure Milk with different concentration of Urea
Treated LPG for Pure Milk with different concentration of Urea
-
Results
0 10 20 30 401619
1620
1621
1622
1623
1624
1625
1626W
avel
engt
h (n
m)
Concentration of Urea (mg)
Uncoated LPG Coated (Enzyme Immoblized) LPG
The comparison of wavelength variation of Pure Milk with different concentration of Urea in coated and uncoated LPG
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• CONFIGURING OF EXISTING OPTICAL SENSORS WITH FIBER OPTICS
• EVOLUTION OF COST-EFFECTIVE AND EFFICIENT DESIGNS
• APPLICABILITY TO NEWER AREAS
• SENSOR DESENSITIZATION AND PACKAGING
• INTEGRATION WITH MICROMACHINED ELEMENTS
• MULTIPLEXING & DISTRIBUTED SENSING
TRENDS
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Remarkable possibilitiesAn interesting & promising futureThe technology behind the fabrication, packaging and installation of FBG sensors has been presented for use in the structures.
Laboratory testing has been demonstrated involving the embedment of FBG sensors in the concrete beam and their performance have been presented under variable loading conditions. Field trials using packaged FBG sensor in distributed configuration on the concrete bridge on NH24 near Hapur have also been demonstratedBio-sensing based on LPG sensor for different applications have been experimentally demonstrated.
Summary
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References1. Fundamentals of Fiber Optics in Telecommunication
and Sensors Systems, Edited by Bishu P Pal; Wiley Eastern Limted, New Delhi, Bangalore, Pune
2. Optical Fibre Sensors, Components & Subsystems, Vol. 1,2,3 & 4, Edited by Brian Culshaw & John Dakin; Artech House, Boston/London
3. Optical Fiber Sensor Technology – Fundamentals, Edited by K.T.V. Graltan & B.T. Meggitt; Kluwer Academic Publishers; Boston/ London
4. Fiber Optic Smart Structures, Edited by Eric Udd; John Wiley & Sons, Inc; New York/Tronto/Singalore
5. Optical Fiber Sensor Technology, Edited by K.T.V.Grattan & B.T. Megitt; Chapman and Hall; London/Glasgow/New York/Madras
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Slide Number 1Slide Number 2Optical Fiber SensorSlide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Optical Fiber Sensor TypesSlide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Fiber Bragg GratingsFBG SensorsSlide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Slide Number 51Slide Number 52Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Slide Number 60Slide Number 61STRUCTURE OF A BIO-SENSORSlide Number 63Slide Number 64Slide Number 65Slide Number 66Slide Number 67COATING OF APTES/ENZYME ON LPFGSlide Number 69Slide Number 70Slide Number 71Slide Number 72Slide Number 73Slide Number 74Slide Number 75Slide Number 76Slide Number 77Slide Number 78