l14_ascos_09_lieberman

8/7/2019 L14_ASCOS_09_Lieberman

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Optical Chemical Sensorsfor Environmental Analysis

R. A. LiebermanSeptember, 2009


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OPTICAL CHEMICAL SENSORS

Optochemical Detection TechniquesOptochemical Detection Instrumentation

Optochemical Detection Formats


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Optochemical Detection Techniques


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Direct Spectroscopy Definition: Measuring the color of light to detect chemicals

Absorption/Reflectance

Oldest chemical detection technique UV-Vis-IR still dominates environmental detection

Modern frontiers: THz, deep UV(?)

Luminescence Accepted standard for hydrocarbon detection

Modern frontiers: Single-molecule detection

Raman Practical at last (made possible by lasers & holofilters)

Modern frontiers: Extreme signal enhancement (SERS)


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Titration Definition: Using chemical reactions to detect

chemicals

Oldest analytical chemical detection technique Major thrust in late 19th and early 20th centuries

Eclipsed by spectroscopy; revived in late 20th century

Current practice ranges from rediscovered inorganicreagents to fluorescent-labeled antibodies

Modern frontiers: Increased analyte specificity (MIPs, designed molecules)

Improved performance (q-dots; NIR dyes)

New formats (optrodes, arrays, etc. see following slides)


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Refractometry

Definition: Measuring refractive index to detectchemicals

First used to measure concentrations in known solutions Total Internal Reflection (e.g., Abbe)

Common in food, petrochemical, other industries

Surface Plasmon Resonance

Used in commercial biochemical detectors

Modern frontiers: nanophotonics-enabled plasmonics


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Refractometry

Optical path shift detection

Grating-based (planar; long-period fiber Bragg)

Interferometer-based (fiber optic M-Z/F-P, integrated optic) Propagation constant measurements

Waveguide pointer

Waveguide cutoff

Ellipsometry (is this polarimetry?)

Modern frontier: Coupling refractometry withtitration (e.g. DNA oligos, antibodies, otherrecognition elements)


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Polarimetry Definition:Measuring polarization to detect chemicals

Optical rotation measurement Classically used to measure sugar concentration Frontier: Chirality measurement for biomolecule detection

Circular dichroism rarely used in sensing (small signal, shortwavelengths)

Nephelometry Definition: Measuring elastically scattered light to

detect chemicals Most-used air quality measurement (particle count)

Can be used to detect titration reactions


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Optochemical Detection

Instrumentation


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Optical Elements Integrated Optic Waveguides

Planar lightwave circuits (PLC) generally SiO2 on Si;

fabricated using semiconductor processing techniques Polymer integrated optics

Wide range of materials

Many fabrication techniques: Embossing; stamp-printing, ink-jetprinting, photolithographic production

Advanced Materials

Nano-optical structures Metamaterials

Controlled-geometry plasmonic features


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Optochemical Detection Formats Fiber-assisted direct spectroscopy

Silica fiber technology deployed everywhere Chalcogenide & Fluoride gaining acceptance

New frontier: new fiber designs (photonic crystal; photonic

bandgap; hollow-core) will double spectral range Fiber-assisted titration

Fiber optrodes

Distributed intrinsic chemical agent sensing

Multipoint active chemical sensors (gratings/scatteringcenters couple light to sensor element)


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Optochemical Detection Formats Fiber-assisted refractometry

Tapered fibers

Fiber-tip Fabry-Perot optrodes

Long-period fiber Bragg gratings (FBGs)

Fiber optic Mach-Zehnder interferometers

Fiber optic SPR probes

Simple Fresnel reflectance probes

Fiber-assisted indirect measurements Strain-inducing coatings on fibers with FBGs Strain-inducing coatings on fiber interferometers

Stain-inducing microbending on fibers in cables


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Integrated optic titration Waveguide arrays with sensor claddings Waveguide arrays with sensor cores

Interferometers with sensor coatings

Integrated optic refractometry Interferometers without coatings

Waveguide pointer

Plasmon waveguides Passive

Active



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ENVIRONMENTAL ANALYSIS

Environmental MediaEnvironments

Chemical Targets


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Environmental Media


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Water

Drinking water

Recreational water

Groundwater

Open water


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Air

Indoor air

Industrial emissions

Local air contamination

Global atmosphere


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Earth

Soil surface

Other surfaces

Subsuface


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Fire

Smoke detection

Flame detection

Combustion control/monitoring


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Environments


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Industrial/Commercial Environments Factories/Refineries

Process control

Legal compliance

Health/safety

Landfills Leakage

Fire/toxin safety

Mines Legal compliance

Health/safety

Other: Restaurants, hospitals, etc.


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Consumer/Home Environments

Indoor air quality

Smoke detection

Home water quality monitoring


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Agriculture/Wilderness Environments

Lake, stream, ocean monitoring

Pollution

Chemical balance

Marine/atmosphere interface (CO2 balance)

Farm runoff characterization

Agricultural soil quality measurement


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Chemical Targets


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Chemical Targets Natural

Toxic minerals in groundwater (Arsenic, lead, other minerals) Smoke and fire byproducts (PAHs, etc.)

Biotoxins (e.g. microcystin from cyanobacteria) Manmade

Factory effluent Stack gases (NOx, SOx, CO, CO2)

Liquid outfall (100s of chemical bypoducts & waste products) Fugitive emissions

Polyaromatic hydrocarbons other hydrocarbons

Accidental releases

Chlorine, ammonia, methyl isocyanate, other industrial products Reaction intermediaries & raw materials (oil)

Purposeful releases Terrorist attack Industrial sabotage


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OPTICAL CHEMICAL SENSORS FOR

ENVIRONMENTAL ANALYSIS --EXAMPLES

Biotoxin Detection in Water

Toxic Chemical Detection on Surfaces

Toxic Chemical Detection in Air

Stack Gas Monitoring Factory Effluent Monitoring

Groundwater Monitoring Carbon Monoxide Monitoring

Fire Precursor Detection


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Drop of water containing pathogens is applied on thetest strip.

Sample reacts with the reagents on the test strip and istransported across the membrane.

Quantum dot (QD) conjugated reagents bind to thespots on the microarray.

QDs that emit at different wavelengths ensure thatcross reactivity or nonspecific binding can be identified.

Measuring fluorescence signals from multiple quantumdots at each spot improves specificity Increases the viability of multiplexed field test strips.

Fluorescence of the QDs is measured with a portablereader.

Fluorescence intensity is related to the concentration oftoxin in the sample.



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Lateral Flow Strip for Single Pathogen


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Lateral Flow Assay Process

Sample Application

Sample Migration

Pathogen Detection


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Multi-Pathogen Lateral Flow Strip

Multiple QD-labeledantibodies on reagent pad

Multiple antibody spots

replace capture line

Multiple antibody spotsalso replace control line


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Quantum Dot Fluorescent Labels

Make Multianalyte Biosensors PracticalUnlimited choice of emission wavelenghsExtremely broad excitation band

Single wavelength can excite all fluorophoresLarge Stokes shiftNo photobleachingSame matgerial used in all fluorophores

Same synthesis process for all fluorophores


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IOS Quantum Dot Fluorescence Spectra


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E. Coli Assay Response

y = 6E-05x + 3.2842

R2

= 0.9769

0

2

4

6

8

10

0 20000 40000 60000 80000 100000 120000

E. coli, CFU

Intensity,

AU


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Pseudomonas Aeruginosa Assay Response

0.00

1.00

2.00

3.00

4.00

5.00

6.00

0 1 2 3 4 5 6 7 8

PA cells (x104)

Intensity(au)


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Toxic Chemical Detection

on Surfaces


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Toxic Chemical Detection on Surfaces

OpticalFibers

Optical

FiberProbe

BioProbe

Bacteria

on Surface

Laptop PC

LightSignals


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BioProbe Operation

Compound excitation /detection probe

5mm diameter fiber bundle

Customized probe head

Can use single fiber

LED source excites bacterial fluorescence

Simplified detection unit selects for wavelengths

characteristic of living cells Can tune for selected biotoxins


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Life Detection Through Autofluorescence


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BioProbe System Components

Reader & Optical Cable

Probe Head (close-up)


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Analysis Software

Windows-driven GUI

Computer-optimizedsignal levels

User-settable alarm

threshold


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System Performance

Linear Detection of Biomarker by BioProbe

0.4

0.6

0.81.0

1.2

1.4

1.6

0.0 0.2 0.4 0.6 0.8 1.0Biomarker Concentration Factor

(Fraction of Toxic Level)

S

igna

lLevel


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Monitoring Bacterial Biofilm Degradation

P. fluorescens Biofilm on Clear Polycarbonate

Treated with 37% Formalin

3700

3900

4100

4300

4500

4700

4900

0 5 10 15 20 25

time (min)

PMToutpu

t(mV)

Live biofilm covered w ith 200 L

deionized w ater (4707 mV)

Addition of 1 drop

formalin (4609 mV)

Addition of another 5 drops

formalin (4485 mV)

Addition of 1 mL

formalin (3970 mV)

Addition of 5-10 drops

formalin (3870 mV)


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BioProbe System Bacterial Response

BB aa cc tt ee rrii aa ll

SSpp ee cc ii ee ss

AA vv ee rraa gg ee

BB aa cc tt ee rrii aa ll

DDee nn ss ii tt yy ((cc ffuu //cc mm 22 ))

MM ee aa nn VV oo ll tt aa gg ee

DDii ffffee rree nn cc ee

bb ee tt ww ee ee nn BB aa cc tt ee rrii aa aa nn dd

WWaa tt ee rr ((mm VV ))

Pseudomonas

f luorescens 3.10 x 10 5 850

Pseudomonas

aeruginosa 5.09 x 10 6 800

Staphy lococcusaureus 1.25 x 10 7 580

Staphy lococcus

ep idermid is 1.84 x 10 7 750


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Life DetectionDifferentiation between Live and Killed Bacteria by

BioProbe

0

500

1000

1500

2000

2500

3000

3500

Sample 1 Sample 2 Sample 3

Bacterial Films on Polymer Surface

SignalLevel(mV)

live samples

killed samples


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Toxic Chemical Detection in Air


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Distributed Intrinsic Chemical Agent Sensing

and Transmission (DICAST) System LINEAR sensor, not a point sensor

Sensor cables respond to target chemical anywhere over

sensor length Optical fibers in the cables are intrinsically sensitive to

individual chemicals

Two optoelectronic detection systems: Alarm-style

Alerts user if even a single meter of cable is exposed

Self-referenced phase-locked-loop gives high-sensitivity and lowfalse alarm rate

Position-resolved:

Locates precise position of chemical agent

Self-referenced optical time domain reflectometry differentiatesbetween chemical and physical changes in fiber cable


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DICASTSensor Principle:Chemically-Induced Cladding Loss

Light Input

Output

n1

n2Glass fiber core

Polymer fiber cladding

Chemical agent

Interaction of chemical agent with indicator in cladding changes

optical properties Light propagating through sensor fiber core interacts with cladding

through evanescent field

Well-known cause of transmission loss in communications fiber

Indicator moleculesembedded in cladding


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From Light Launch to Equilibrium

the Spatial Transient

Source: Snyder, A.W. & Love, J.D., Optical Waveguide Theory


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DICASTSensor Fibers

Conventional fiberfabrication

Patented optical design

Proprietary sensorycladding

Cl2 HCN

H2S Sarin/Soman


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Hydrogen Cyanide Cladding Material

HCN 50PPM 50% RH 15 min

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.60.7

0.8

350 450 550 650 750 850

Wavelength (nm)

Absorb

ance

50 ppm-1min

Op. 532


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Hydrogen Cyanide Sensor Fiber Performance

TEST031805-1

-5

-4

-3

-2

-1

0

1

0 60 120 180 240 300 360 420 480 540 600

Exposure Time (sec.)

Sensor

Signal(dB/m)

50ppm

50ppm

5ppm

5ppm

5ppm

Chemical Exposure Begins

Note: Integrative (dosimetric) response

fibers respond faster to higher concentrations


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Note: Response remains strong after 425 days @ 23C

Chlorine-Sensitive Cladding Material

Cl2 10 ppm 50% RH 2min

-0.01

0.09

0.19

0.29

0.39

0.49

300 350 400 450 500 550 600 650 700 750 800 850

Wavelength (nm)

absor

bance

10 ppm 2min

Op. 650


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Chlorine Sensor Fiber Performance

SY63 Response 10 ppm Cl2/Air 10%RH

-0.5

0

0.5

1

1.5

2

2.5

4 4.5 5 5.5 6 6.5 7

Time (min)

dB

650 nm

1310 nm

gas on

Absorbance


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Nerve Agent Sensor Cladding Material

Soman ResponseSarin Response


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DICASTSensor Cables

Air-permeable sheath Lets air in to react with fibers

Provides rugged protection againstshear stress


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Full Cable DICAST System Response(Four Fibers, Two Wavelengths)

50ppm HCN 23C/50%RH

KEYHYDROGEN CYANIDE FIBERHYDROGEN SULFIDE FIBER

CHLORINE FIBERNERVE AGENT FIBER

Solid: VisibleDotted: Infrared

HCN on


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DICASTOptoelectronics

Zone-Alarm System

Position Resolved System


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DICAST Zone-Alarm Optoelectronics

End-to-end fiber transmission measured

Sensor cables linked to system through

commercial multimode cables

Dual-wavelength illumination

Visible: Responds to chemical agent Infrared: Reference wavelength

Sources modulatedfrequencies

Lock-in detection Eliminates stray light effects

Increases signal-to-noise ratio


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SENSOR 1 (BROADBAND H2S)

SENSOR 1 (BROADBAND H2S SPARE)

SENSOR 2 (CHLORINE)

SENSOR 3 (NERVE AGENT)

CABLE INVENTORY:

4 ea 50 ft 4-SENSOR DICAST CABLES

3 ea 50 ft 3-FIBER DISTRIBUTION CABLES

6 ea 80 ft 3-FIBER DISTRIBUTION CABLES

2 ea 480 ft 4-FIBER DISTRIBUTION CABLE

4 ea 260 ft 3-FIBER DISTRIBUTION CABLE

Zone-Alarm DICAST SystemMetro Platform Test Site: 4 Fibers, 4 Zones

OUT1B

OUT1C

OUT1A

OUT1D

23July07 v5

Passenger Platform Edge

IN1A

IN1B

IN1C

IN1D

1A1B1C1D

1AS1BS1CS1DS

2A2B2C2D

3D 3C 3B 3A

IN2

IN3OPEN

OPEN

50 ft 50 ft 50 ft0 ft0 ft 80 ft0 ft

480 ft

260 ft

spare spare spare spare

2 Std Cables2 Std Cables2 Std Cables

2 Std Cables

1 Std Cable

1 Sensor Cable

1 Std Cable

1 Sensor Cable

1 Std Cable

1 Sensor Cable

1 Std Cable

1 Sensor Cable

4 Std Cables

From TC&C Room


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Zone-Alarm DICAST

Software Local interface provides

immediate Safe/Alarm

status

Neural net combinesdata from four fibers to

eliminate false alarms Internet uplink provides

remote monitoring

capability


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Position-Resolved DICAST

Visible Wavelength Optical Time Domain Reflectometry (OTDR)

Short pulse launched into fiber

Rayleigh scattering returns fraction of light toward source Time-of-flight determines location sensed

Optical loss between launch and location determines intensity

In DICAST: Plot indicates chemical dose versus location

(10 cm)

t= 0.5 nsec

t= 10 nsec

t= 20.5 nsec

2 meters


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14 Meter Fiber Exposed to 100 ppm Chlorine

2.6dB/m

0.25 dB/m

1.9dB/m

Exposure20 sec20 sec30 sec


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Parameter RequirementSensitivity Alarm when one meter or more is exposed

to 10% of toxic dosage dosage

Specificity Will not alarm with defined interferants

Resolution Within 1 meter along fiber (OTDR)

Response time Less than 10 sec for toxic dose IDLH/LCT50

Less than 1 minute for 10% of toxic dose

Cable length 60 meters chemically sensitive;

300 meter leads

Cable lifetime Greater than 1 year

Calibration Electronic (no test gas needed)

False Alarm rate Less than 1%

DICASTSystem Specifications


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Factory Effluent Monitoring


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Continuous Flow Assay for Low Vapor

Pressure Toxic Industrial Compounds


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Microsphere-Bound Displacement Assay


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Labeled Microspheres (10 m)

Labeled Beads Unlabeled Beads


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Target Antigens

Carbaryl

[63-25-2]

Diphacinone

[82-66-6]Parathion

[56-38-2]

Surrogate Antigens

Q D Bi L b li


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Quantum Dot Bio-Labeling

CdSe core, ZnS shell quantum dots Coated with cysteine-lysine peptide chains

Cysteine binds to QD Lysines bind to surrogate antigen


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Fluorescence Excitation & Collection


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Benchtop Model of Packaged System

Package:

Excitation

Collection Flow cell

External:

Pump

Reagent

Computer Signal processing

Power supply


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Vortex Air Sampler/Extractor

40 liters/min. flow rate

70% collection efficiency


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0

10002000

3000

4000

5000

450 500 550 600 650

no loss of beads

=1800 c s

Displacement Immunoassay of Phenanthrene

Surrogate antigen: 2-aminonaphthalene

Sample: 150 ppm phenanthrene


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Continuous Flow Water Effluent Monitoring

Same platform as

LVP-TIC monitor Ab/Ag system for

new targets (e.g.,PAHs, pesticides)

Water pump

replaces airconcentrator


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Groundwater Monitoring


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Techniques for In Situ Monitoring

Remote fiber optic spectroscopy Excitation fiber carries laser light downhole

Collection fiber returns Raman & fluorescence to spectrometer Neural network identifies & quantifies pollutants

Locally replenished liquid optrode Liquid-phase irreversible chemical indicator system

Dissolving solid supplies continuous stream of reagent

Excitation & collection through separate fibers

Neural network identifies & quantifies pollutants

Active chemical refractometry Long-period fiber grating diffracts light to cladding modes

Target compound swells chemically selective coating

Neural network identifies & quantifies pollutants


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Raman Spectra of Target Compounds


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Mixed Raman Spectrum 3 Targets


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Mixed Raman Spectrum CHCl3 in Water


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Fluorescence Spectra of Target Compounds


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Mixed Spectra: Groundwater & Targets

-10

1

2

3

45

6

240 340 440

nm

Norm.

Lum

inescenc

e Gr.water

Benzene1500ppm

Toluene120ppm

Xylene6ppm


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Hybrid Neural Network Design


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User Interface: Presenting Purity

True Ratios

0% 20% 40% 60% 80% 100%

GNDA

GNDB

benze

tolue

xylen

Zoom In on Targets


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Solid-Phase Replenished Optrode

Groundwater diffuses through porous membrane

Reaction consumes reagent

New reagent released by polymer

Optical path avoids high-concentration reservoir

Controlled-ReleasePolymer

C ti C l F Chl i t d C d


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Creating Color From Chlorinated Compounds A strong base abstracts the acidic proton to generate trihalomethyl

anionHO-+ HCX3 H2O + :CX3-

The unstable conjugate base loses a halide ion and generates adivalent carbon species known as carbene

:CX3- X- + :CX2

This electron-deficient intermediate, reacts with molecules such aspyridine, forming a highly colored product [Fujiwara, 1917] The traditional Fujiwara chemistry (pyridine/OH-) used alkalis

(NaOH and KOH) in water -- insoluble in pyridine. Reaction productis formed only at the interface.

Andersen and Andersen [1990] showed a single-phase Fujiwarasystem that utilized pyridine and a hindered nitrogen base,specifically a tetraalkylammonium hydroxide

IOS has developed all-solid-phase Fujiwara chemistry, using solid

pyridine derivatives

Improving on Fujiwara


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Improving on Fujiwara

HO-+ HCX3 H2O + :CX3-:CX3- X- + :CX2

Multiple Color-Producing Reactions


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Multiple Color Producing Reactions(chloroform 10 ppm)

1,2-Bis(4-Pyridyl)-Ethane

(0.2 M in THF) and TBAH (0.2M)

1,2-Bis(2-Pyridyl)-Ethylene

(0.2 M in THF) and TBAH (0.2M)

4,4'-Dimethyl 2,2'-Dipyridyl(0.2 M in THF) and TBAH (0.2M)


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Calibration Curve for Chloroform


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Photobleaching Resets Reaction

Relocatable Groundwater Monitoring


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Relocatable Groundwater MonitoringUsing a Cone Penetrometer

Fiber Bragg Gratings


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Fiber Bragg Gratings

Periodic variation in waveguide core refractive index

Short-period gratings strongly reflect wavelengths

that are integral multiples of the grating period For extremely long periods, guided modes in fiber

core are scattered into cladding modes


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Fiber Bragg Grating Spectral Behavior

Single Mode FBG Reflection Spectrum


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Single Mode FBG Reflection Spectrum

Measured with IOS System

Long Period Fiber Bragg Gratings


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Long-Period Fiber Bragg Gratings

For multimode fibers, Long Period Bragg Gratings(LPGs) yield very rich transmission/reflection spectra

Coupling to cladding surface means that spectrum ofLPG depends on refractive index outside of cladding

Can access the environment directly from the core

(CLADDING evanescent field coupling

0

20

40

60

80

100

5 50 6 0 0 65 0 7 00 75 0

Wa ve length (nm)

Tran

smittance

E l 49 K


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Example: 49 ppm Kerosene vapor

in Contact With Surface of LPG-Fiber

S lid Ph E i C i E h


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Solid-Phase Extraction Coatings Enhance

LPG Response to Target Compounds

Differential permeability

Permeable to target vapors

Reduced permeability for other compounds

Solvent-induced refractive index shifts Dilution average of two indices in volume

Swelling increases volume


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Kerosene-Aquasil-LPG Interaction

0

20

40

60

80

100

500 550 600 650 700 750 800

Wavelength (nm)

Transmittance(%

)

R f LPG Fib t 63 D


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Response of LPG Fiber to 63 ppm Decane

Coating: LLNL UR3

R f UR3 LPG Fib t 76 O t


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Response of UR3-LPG Fiber to 76 ppm Octane

0

20

40

60

80

100

560 610 660 710 760Wavelength (nm)

Transmittanc

e(%)

LPG Fiber Response to Solvent Vapors


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LPG Fiber Response to Solvent Vapors(Coating: Aquasil)

0

20

40

60

80

100

560 610 660 710 760

Wavelength (nm)

Tr

ansmittan

ce(%

Dichloromethane Decane Toluene BKG


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Error Histogram for 100 Measurements


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Error Histogram for 100 Measurements


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Environmental Air QualityMonitoring

Environmental Gas Monitoring


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Environmental Gas Monitoring

Photodetector

Lightsource

NeuralNetwork

O2

CO2

CO

H2O

Photodetector

Multi Gas Air Quality Monitoring


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Multi-Gas Air Quality Monitoring

Chemically active sensors

Optrodes

Indicator-doped porous-glass PICs

Multiple analytes

Multiple indicators and Multiple reference channels

Multiple wavelengths

Neural net signal processing Removes cross-response

Improves quantitation

Four-Optrode Long-Term Exposure


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Four Optrode Long Term Exposure

(Nitrogen Background)

0 50 100 150 200 250 300 350 400

0

500

1000

1500

Time (min)

IncidentLightPower

Photodetector1Photodetector2Photodetector3Photodetector4

Four-Optrode Long-Term Exposure


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Four Optrode Long Term Exposure

(Ambient Environment)

0 50 100 150 200 250 300 350 400 4500

100

200

300

400

500

600

700

800

900

1000

Time (min)

IncidentLig

htPower

Photodetector1

Photodetector2Photodetector3Photodetector4


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Vaskas Complex as a CO Indicator

Spectral Response to Carbon Monoxide


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Spectral Response to Carbon Monoxide

Carbon Monoxide Optrode Response


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Carbon Monoxide Optrode Response

Carbon Dioxide Optrode


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Carbon Dioxide Optrode

(Severinghaus Optrode)

CO2 (aq) + H2O > H2CO3 (Kh = 2.6 X 10-3)

H2CO3 + H2O HCO3- + H3O+ (K1 = 2.2 X 10-4)

HCO3- + H2O < > CO32- + H3O+ (K2 = 2.5 X 10-10

)

CO2 shifts carbonate equilibriumResulting pH triggers change in fluorescent indicator

Fluorescence Response of CO Optrode


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Fluorescence Response of CO2 Optrode

CO2 Response Curve


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CO2 Response Curve

Neural Net Deconvolution of


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Multichannel Data


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Fire Precursor Detection

3048 & 3084 & 3097

Fire Precursor Detection in Aircraft


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Fire Precursor Detection in Aircraft

Heated materials emitvapors & gases

Carbon monoxide Formaldehyde

Polymer/monomer

Gases have distinctNIR spectra

Optical detection ofprecursors detectsfire before it occurs

Carbon Monoxide Absorption Spectrum


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p p

Conventional Modulation Spectroscopy


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p py

Modulation

(Pressure, Stark)

Broadband

Light Source

Broadband

Light Source

Measurement

Cell

Measurement

Cell

Optical Fiber

(Multimode)Reference

Cell

Reference

Cell

Bandpass Filter Detector

Modulation

(Frequency, Shift)

a)

b)

Multi-Wavelength Modulated Fiber Laser


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g


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Thermo-Stabilized Multiline Laser

7-Line Fiber Laser Tuned for CO


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7 Line Fiber Laser Tuned for CO

20 ppm CO Detected With Multi-line Laser


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Optical Chemical Sensors:Good for Environmental Analysis!


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TEST031805-1

-5

-4

-3

-2

-1

0

1

0 60 120 180 240 300 360 420 480 540 600

Exposure Time (sec.)

SensorSignal(dB/m)

50ppm

50ppm

5ppm

5ppm

5ppm

0

1000

2000

3000

4000

5000

450 500 550 600 650

no loss of beads

=1800 cps

0

20

40

60

80

100

660 680 700 720 740 760

Wavelength (nm)

Transmittance(%

Dichloromethane Decane Toluene BKG

00 0 0

0 50 100 150 200

250

500

1000

2500

5000

250

500

1000

2500

50005000 50005000

45

40

35

30

25

20

15

105

Signal(ArbittraryUnits)

Time (min)

PR3

PR3

Cl

Ir CO

CO

PR3

PR3

Cl Ir CO

C

O

k1

k1

Good for Environmental Analysis!

Thanks to


127/127

Thanks to

Funders National Science Foundation

(NSF)

National Institutes of Health(NIH)

National Aeronautics andSpace Administration (NASA)

Environmental ProtectionAgency (EPA)

U.S. Department of Defense

U.S. Department of State

Workers Dr. Glenn Bastiaans

Ms. Manal Beshay

Dr. Kishology Goswami Mr. Jeffrey Iida

Dr. Lothar Kempen

Dr. Edgar Mendoza

Dr. Vladimir Rubtsov

Dr. Indu Saxena

Dr. Roland Suri

Dr.Igor Ternovskiy Dr. Srivatsa Venkatasubbarao

Audience

l14_ascos_09_lieberman

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