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8/8/2019 e-nose by harsha
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A TECHNICAL SEMINAR ON
ELECTRONIC NOSE
PRESENTED BY
MALLADI.H.S.SHOWRI
(07EK1A0429)
ELECTRONICS & COMMUNICATION
Under the guidance of
Mr.P.Micheal,M.Tech
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INTRODUCTIONINTRODUCTION
~WHAT IS AN E NOSE?
~ WHY E NOSE?
~ WHAT IS ODOUR?
~ WHAT ARE VOCS?
~ WHAT ARE RECEPTORS?
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ELECTRONIC NOSEELECTRONIC NOSE Electronic nose or (e nose) is a device that identifies the specific
Components of an odour and analyzes its chemical makeup to
Identify it.
An e nose consists of mechanism for identification of chemical
detection such as an array of electronic sensors and a mechanism
for pattern recognition
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ODOURODOUR~odour in a substance is due to VOCS or volatile
Organic compounds which evaporate and get carried
Away by air
RECOGNITIONRECOGNITION~receptors in human nose act as binding sites forVOCS these vocs are then processed by brain and
We recognise the smell.
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MAIN COMPONENTS OF E NOSEMAIN COMPONENTS OF E NOSE
SENSING SYSTEM
PATTERN RECOGNITION SYSTEM
SUB COMPONENTSSUB COMPONENTS
SAMPLE DELIVERY SYSTEM
DETECTION SYSTEM
COMPUTING SYSTEM
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The sample delivery system enables the generation of the headspace (volatilecompounds) of a sample.
More on workingMore on working
The detection system, which consists of a sensor set, is the reactive part of theinstrument. When in contact with volatile compounds, the sensors experience a change
of electrical properties. Each sensor is sensitive to all volatile molecules but each in
their specific way.
The computing system works to combine the responses of all the sensors whichrepresent the Input for the data treatment ,it then performs global finger print analysis an
provides results
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BLOCK DIAGRAMBLOCK DIAGRAM
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WORKING OF E NOSEWORKING OF E NOSE
In a typical e-nose, an air sample is pulled by a vacuum
through a tube into a small chamber housing the electron
sensor array. The tube may be of plastic or stainless st
A sample-handling unit exposes the sensors to the odoranproducing a transient response as the VOCs interact wit
active material.
The sensor response is recorded and delivered
to the Signal-processing unit.
Then a washing gas such as alcohol is applied to the arra
for a few seconds or a minute, so as to remove the odor
mixture from the active material.
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INTRODUCTION TO SENSORSINTRODUCTION TO SENSORS
A sensor is a device which can respond to some properties of the environment and
transform the response into an electric signal. The general working mechanism of asensor is illustrated by the following scheme :
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TYPES OF SENSORSTYPES OF SENSORS
E-nose is classified based on the type of sensors used.
1.Conductivity Sensors
2. Piezoelectric Sensors
3. FET gas Sensors
4. Optical Sensors
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Conductivity sensorsConductivity sensors
Both of which exhibit a change in resistance when exposed to volatile organic
compounds.
Metal oxide gas sensors can be subdivided into:
Thick film devices (depositing a paste of material between two electrodes)Thin film devices: they use vapor deposition technologies in order to obtain a
very thin film of metal oxide between two electrodes.
Metal oxide type
Polymer type
Polymer SensorsHere the active material is a conducting polymer from such families as the
polypyroles, thiophenes, indoles or furans. Changes in the conductivity of these
materials occur as they are exposed to various types of chemicals, which bond with
the polymer backbone.
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If a different compound had caused the air to change, the pattern of
the polymer films' change would have been different:
Each polymer changes its size, and therefore its resistance,
by a different amount, making a pattern of the change
THE ELECTRONIC NOSE SMELLS SOMETHINGTHE ELECTRONIC NOSE SMELLS SOMETHING
e- e- e
-
e-e-e
-
e-e-
e-
e- e-e-
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Optical Fiber Sensors
These utilize glass fibers with a thin chemically active material coating ontheir sides or ends.
A light source at a single frequency is used to interrogate the active
materials which responds with the change in colour to the presence of VOCs.
Advantages: Cheap and easy to fabricate. Arrays of fiber sensors havewide range of sensitivities. Differential measurement is possible to avoid
common mode noise.
Disadvantages: Complexity of the measuring system.
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Range of applicationsRange of applications
Food industry applications
environmental monitoring
Safety and security applications
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Fish inspection
Automated flavor control
Inspection food by odour
Food industry applicationsFood industry applications
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Environmental monitoringEnvironmental monitoring:
Identification of toxic wastes
Analysis of fuel mixtures
Detection of oil leaks
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Examining vehicles for drugs
smart fire alarms
Fire alarms in nuclear plants
Screening airline passengers for explosive
Safety and security applicationsSafety and security applications::
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Conclusion :-
1. It is highly expensive, so it is not being used in
daily medical diagnosis. So, there is need of
inventing the low cost sensors.
2. E-Nose faces problems in recognizing multiple
patterns, which has to be rectified .
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