e-nose by harsha

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

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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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e-nose by harsha

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