THE ELECTRONIC NOSE

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THE ELECTRONIC NOSE ITS POTENTIAL
Miss Asha Joseph Dr. Peter Lykos
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All Those Responsible

• Dr. Peter Lykos
• Dr. Joseph Stetter
• Dr. Bill Penrose
• Dr. Pravin Patel
• Chris Morong
• Asha Joseph
• Yan Hu
• John Carr
• Luke Jarymowycz

• Doug Sievers
• Archan Mehta
• Justin Henry
• Jamal Hussein
• Joel Ziemke
• Jerome Hannecart
• Zaki Shaikh

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Contents

• What is an Electronic Nose?
• Comparison with a Biological Nose
• Uses
• Design of the Electronic Nose
• Sampling and Distribution
• Sensors and Electronics
• LabVIEW and Pattern Recognition
• The Experiment
• Future of the Electronic Nose

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What is an Electronic Nose?

• An Electronic Nose is a system that uses the
  pattern of responses from an array of gas sensors
  to examine and identify a gaseous sample.

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Our Electronic Nose
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An Electronic Nose
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Analogy Between the Electronic Nose and the
Biological Nose

• Inhaling ? Pump
• Mucus ? Filter
• Olfactory Epithelium ? Sensors
• Binding With Proteins ? Interaction
• Enzymatic Reactions ? Reaction
• Cell Membrane Depolarized ? Signal
• Nerve Impulses ? Circuitry Neural Network

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How Does a Biological Nose Work?
A ROSE !
Circuitry NN
Mucus (filter)
Receptor Protein (sensor)
Nerve
Would a rose smelled by any other nose smell as
sweet?
Input
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The Basic Design of an Electronic Nose
Array of Signals
Vapor
Result
Pattern Recognition
Array of Sensors
Sample
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Why is an Electronic Nose Better?

• Trained human sniffers are expensive
• Individuals vary
• Hazardous Chemicals
• Can be done in real time for long periods

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Where Electronic Noses Are Used

• Automotive
• Food safety
• Telemedicine
• Emergency response
• Military and space
• Environmental monitoring

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Nose Accessories

• Computer Control
• Modulation Sensor
• Switches
• Identical Sampling
• Improved Pattern Recognition Software
• Sampling System
• Gas Collector

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SENSOR MANIFOLD
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First Design Consideration
Linear serial

• Advantages
• Easy to make
• Small volume
• Disadvantages
• Degrades the sample
• Cannot be greatly expanded

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Second Design Consideration
Radial Parallel
Advantages Sample flows equally to each
sensor Disadvantages Complex to make Larger
volume than the linear manifold
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Radial Sensor Manifold
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Sampling What is a sniff?
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What is Sampling?

• Preparing the sample
• Volatile liquids
• Vapor phase sampled directly
• Solids
• Sample may be ground
• Chemical extraction

• Sample delivery
• - Control Variables
• Concentration
• Pressure
• Temperature
• Volume
• Flow rate

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Sampling System
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Switches and Filament
Controlled by LabVIEW Why Computer
Controlled Identical Sample Runs Easy Comparisons
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Sampling System
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Sampling System
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Electronics Instrumentation
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The Modulation Sensor (Filament)

• Hydrocarbons do not cause significant response in
  electrochemical sensors
• Acts like a pseudo-mass spectrometer
• Wider Chemical Profile
• Inactive molecules broken down into
  electrochemically reactive fragments

OFF ON
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Filament controller circuit
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Automation of the Sampling System
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Electrochemical Sensors
GAS
Porous Membrane
Filter
Working Electrode
Gain
Reference
Common
Bias
Signal

H Electrolyte
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CO Oxidation and Reduction
Oxidation Working Electrode CO H2O
CO2 2H 2e- Reduction Common Electrode O2
2H 2e- H2O CO
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Schematic
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LabVIEW Principal Component Analysis
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What is LabVIEW?

• A graphical programming language
• Data Acquisition Techniques
• Data manipulation, creation, and display
• Control hardware

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LabVIEW Block Diagram
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What Can You Do With a Neural Net?

• Just about anything that a regular computer can
  do, only better
• Instead of calculating one step at a time,
  calculates many things at the same time
  (resembles parallel processing)

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Common Neural Net Design
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What is Principal Component Analysis?

• Principal Component Analysis is a method of
  projecting higher dimensional space onto a two
  dimensional plane for easy visualization.
• More of a Statistical Method

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How to Perform PCA?
x X

• Normalize Sensor Array

_

• Scale Data (x-x)/s

• Store all Data as an m x n matrix (A)

T

• A A produces a n x n matrix

• Take Eigenvalues (?) and Eigenvectors (V)

?
k

• Variance

k
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How to Perform PCA? (Cont..)

• Use the two largest eigenvalues and find the
  corresponding eigenvectors
• Take the two eigenvectors and dot them with each
  scaled sensor array (V A )?X
• (V A )?Y
• Plot (X,Y)

i
1
i
2
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How Neural Nets Will Benefit the Electronic Nose

• Sensor responses drift over time
• Change with concentration
• Sample Depletion
• Relate the Pattern of the data
• Find the data that is the closest
• Determine the odor

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How to Work LabVIEW

• Enter the file name
• Enter Sample Code
• Choose Autoscaling
• Click Acquire Data ON
• Click the run Arrow
• Collect Data
• View the PCA

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LabVIEW for Dummiees
http//www.iit.edu/labview
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But Does It Work?
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The Experiment

• Five Samples
• Broth
• Escherichia coli
• Pseudomonas aeruginosa
• Diluted 51 with saline solution
• Continuous stirring
• Each Run 6 minutes
• Repeated 7 times in succession
• Tubes Flushed with air for 4-5 minutes
• Next Sample

Staphylococcus aureus Enterococcus faecalis
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• Broth Run 6 (9-10-99)

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• Broth Run 6 (9-10-99)

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PCA 9-10-99 Different Bacteria
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MOSES II Coffee Data (PCA)
C3
U1
C1
C2
U2
X-Axis ?80 Variance (PC1) Y-Axis ?8 Variance
(PC2)
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FUTURE OF THE E-NOSE
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Future of the Electronic Nose

• Research is being done on IC E-Noses
• Miniaturizing Current Technology
• Combination of several sensors
• Conducting Polymer
• Quartz Crystal Microbalances
• Variable Capacitor
• Manufacture of olfactory nerves

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How and Why Responses Happen

• Sensors respond to different functional groups
• There is cross sensitivity and selectivity
• Not all sensors respond the same way

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Types of Sensors

• Calorimetric
• Conducting (Metal Oxide and Polymer)
• Piezoelectric (QCM and SAW)
• Electrochemical
• NOTE All need transducers

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Calorimetric

• The sensors measure the concentration of
  combustibles species by detecting the temperature
  rise resulting from the oxidation process on a
  catalytic element.

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Conducting Metal Oxide Polymer

• The gas is absorbed onto the surface and the
  resistance changes
• Voltage is proportional to the Resistance
• The change in voltage is measured
• Metal Oxide most popular (200-400C)
• Polymer (Room Temp)

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Piezoelectric QCM SAW

• Quartz Crystal Microbalances
• Quartz crystal resonates
• Polymer coating adsorbs the gas
• Mass change causes a change in frequency
• Surface Acoustic Wave
• Same principles
• Measures the phase shift in the wave

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Special Thanks

• Dean Kallend - Monetary Support
• Dr. Lykos, Dr. Stetter Dr. Penrose
• Mentoring
• Technical support
• Thomas Torres - Machine Shop
• Charles Wenger - Research Librarian

• Citytech - Free Sensors
• Bacharach Inc. - Free Sensors
• Sensor Tek - Free Sensors
• TSI Inc. - Free Sensors
• Starbucks - Free Coffee Samples
• Dr. Pravin Patel
• Bacteria Samples

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Questions?