Electronic Nose1 130413010331 Phpapp01

8/13/2019 Electronic Nose1 130413010331 Phpapp01

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Good afternoon..


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Presented by:

DEBLINA DUTTA CHOWDHURY


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CONTENTS

Introduction(e-nose), e-sensing,

Definition: electronic nose(e-nose),Basic design of an e-nose

Comparison of e-nose with biological nose

The need of an e-nose

The e-nose---An overview

Working principle of an e-nose

Sensor technology in e-nose

Performing an analysis with an e-nose

Applications of e-nose

Conclusion


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Introduction---electronic nose(e-nose)

o Electronic noses are engineered tomimic the mammalian olfactory system.

o Instrument designed to allow repeatable

identifications and classifications of

aroma mixtures.

o Determines the various characteristics

properties of the odour while

eliminating operator fatigue.

e-sensing

Refers to the capability of reproducing human senses using sensor arrays and pattern

recognition systems.


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Definition: electronic nose(e-nose)

o Device intended to detect odors or flavors.

o Can be seen as arrays of sensors able to generate electrical signals in response to

either simple or complex volatile compounds present in the gaseous sample.


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Fig: Basic design of an e-nose


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Biological Nose E-NoseInhaling Pump

Mucus Filter

Olfactory epithelium Sensors

Binding with proteins Interaction

Enzymatic proteins Reaction

Cell membrane depolarized Signal

Nerve impulses Circuitry and neural network

Comparison of e-nose with biological nose

o Each and every part of the electronic nose is similar tohuman nose.

o Comparison Table:


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The need of an e-nose

o

The human sniffers are costly when compared to electronic nose.

o Speedy, reliable new technology of the gas sensors are used in the electronic

nose.

o Detection of hazardous or poisonous gas is not possible with a human sniffer.

o An e-nose also overcomes other problems associated with the human olfactory

system.

o For the confirmation of the values obtained from a sniffer the result obtained

from the sniffer has to be compared with some other sniffers value.

o There lies a great chances of difference in the values got by each individual.


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The e-nose---An overview

o An air sample is pulled by a vacuum pump.

o It is led through a tube into a small chamber consisting of electronic sensor array.

o

A transient response is produced as the volatile organic compounds in the sampleinteract with the surface of the sensorsactive material.

o A steady state response is reached within few minutes.

o This response is then sent to a signal processing unit.


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o

A washing gas such as an alcohol vapour is applied to the array for a few secondsto a minute.

o This is done to remove the odorant mixture from the surface and bulk of the

sensor's active material.

o Finally, the reference gas is again applied to the array, to prepare it for a newmeasurement cycle.

o A variety of basic sensors can be used according to the nose strategy chosen.

o Each sensor in the array has different characteristics.

o The pattern of response across all the sensors in the array is used to identify and/or

characterize the odour.

Contd..


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Working principle of an e-nose

Electronic noses include three major parts:I. a sample delivery system

II. a detection system

III. a computing system

I. Sample delivery system

o Enables the generation of the

headspace (volatile compounds) of

a sample.

o The system then injects thisheadspace into the detection system

of the e-nose.


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II. Detection system

o Consists of a sensor set, is the "reactive" part of the instrument.

o Adsorption of volatile compounds on the sensor surface causes a physical

change of the sensor;they experience a change of electrical properties.

o A specific response is recorded by the electronic interface transforming the signal

into a digital value.

o Recorded data are then computed based on statistical models.

III. Computing system

o Works to combine the

responses of all of the sensors.


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(1) Conductivity sensors

Metal oxide sensors(MOS) Conducting polymers

(2) Piezoelectric sensors

(3) MOSFET sensors

(4) Optical sensors

Sensor technology in e-nose

o The sensor array is clearly the key element. It forms the primary step in the detection or

identification of an odorant.

o The most commonly used sensor s in electronic nose are:


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(1a) MOS (Metal oxide sensors) -

o Adsorption of gas molecules provoke changes in conductivity .

o This conductivity change is the measure of the amount of volatile organic compounds

adsorbed.

o Conducting or conductive polymer gas sensors operate based on changes in electrical

resistance caused by adsorption of gases onto the sensor surface.

(2) Piezoelectric sensors-

o Adsorption of gas onto the surface of the polymer leads to change in mass on thesensor surface.

o This in turn produces a change in the resonant frequency of the crystal.

o This change in frequency is proportional to the concentration of the test material.

(1b) Conducting polymers-


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(3) MOSFET (Metal Oxide Silicon Field Effect Transistor )sensors-

o A volatile organic compound produces a

reaction in the sensing layer(gate).

o This causes the physical property of the

gate to change.

o Thereby the threshold voltage is changed

and thus the channel conductivity.


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(4) Optical sensors-

o Optical sensor systems are somewhat more complex than typical sensor-array systems

having transduction mechanisms based on changes in electrical resistance.

o Optical sensors work by means of light modulation measurements.

Performing an analysis with an e-nose

o As a first step, an e-nose needs to be trained with qualified samples so as to build a

database of reference.

o Then the instrument can recognize new samples by comparing volatile compounds

fingerprint to those contained in its database.

o Thus they can perform the analysis.


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APPLICATIONS OF ELECTRONIC NOSE


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Applications of E-nose

The applications(current) of an electronic nose

include:

o Medical diagnosis and health monitoring

o Environmental monitoring

o Application in food industry

o Detection of explosives

o Space applications(NASA)

o In research and development industries

o In quality control laboratories

o In process and production department


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o in field of crime prevention and security

o detection of harmful bacteria

o detection of drug odours etc.

The possible and future applications of an electronic nose include:


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Medical diagnosis and health monitoring by e-nose

I. Respiratory disease diagnosis-

o Human breath contains thousands of volatile organic compounds (VOCs) in gas

phase.

o E-nose can diagnose respiratory infections such as pneumonia.

o It does so by comparing smell prints from the breath of a sick patient with those of

patients with standardized readings.

o It is also being studied as a diagnostic tool for lung cancer.

II. Urinary Tract infections-

o The e-nose as a potential diagnostic tool for patients affected with kidney diseases, by

distinguishing traces of blood in urine samples.


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III. Cancer detection-

o E-nose is capable of distinguishing between the breath of a

healthy person and a person with cancer.

o The device is especially promising because it is able to

detect cancer before tumors become visible in X-rays.

Environmental monitoring by e-nose

o Environmental applications of electronic noses include:

(1) analysis of fuel mixtures

(2)detection of oil leaks

(3) testing ground water for odours

(4)identification of household odours(5)identification of toxic wastes

(6)air quality monitoring

(7)monitoring factory emissions etc.


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Applications of e-nose in food industry

Analysis of fruit ripening-

o Fruit ripening is associated with an accumulation of

aromatic volatiles during ripening.

o Information from the noses can help in removal of rotten

fruits at the appropriate time.

o This can help in avoiding storage losses due to rots and

fruit diseases.

Detection of explosives

o E-nose is being developed for military and security

applications in the detection of explosives and

hazardous chemicals.


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Space applications---e-nose and NASA

JPL Electronic Nose (e-nose)-A Brief Summary:

o It is a full-time, continuously operating event monitor

used in the International Space Station.

o Designed to detect air contamination from spills and

leaks in the crew habitat

o Provides rapid, early identification and quantification

of atmospheric changes caused by chemical species to

which it has been trained.

o Can also be used to monitor cleanup processes after a

leak or a spill.


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Conclusion

o An electronic nose is a system originally created to mimic the function of an

animal nose.

o Offers a cheap and non destructive instrument that (if properly programmed and

automated) can be operated by non specialists.

o Since the whole process is automatic, the cost of each measurement is very low.

o Finally, the measurement cycle should be faster in order to increase throughput.

o However, this analytical instrument is more a multi-sensor array technology

than a real nose.

o Whatever the sensor technology, it is still far from the sensitivity and selectivity

of a mammalian nose.

o Therefore, its aim is not to totally replace either the human nose or other

analytical methods.


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ACKNOWLEDGEMENT

On preparing this presentation on Electronic Nose(e-nose) ,we have gained quite someknowledge about this topic which we were unaware of before. We have found the topic

quite interesting and would like to explore more about this topic in the future . We

would like to thank our Sir, Mr. Abhijeet Pal for giving us an opportunity to do this topic

for the seminar.


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REFERENCES

o www.wikipedia.org

o www.slideshare.com

o www.powershow.com

o www.google.com
http://www.wikipedia.org/http://www.slideshare.com/http://www.powershow.com/http://www.google.com/http://www.google.com/http://www.powershow.com/http://www.slideshare.com/http://www.wikipedia.org/


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Thank you..

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Electronic Nose1 130413010331 Phpapp01