o Introduction

o Previous work done

o Working of e-nose

o E-nose vs. Bio nose

o Applications

o Advantages

o Challenges involved

o Future aspects

o Conclusion

o References

o An electronic nose is a

device that identifies the

specific components of

an odor and analyzes its

chemical makeup to find

it.

o It consists of certain

mechanisms such as an

array of electronic

sensors for chemical

detection and artificial

neural network for pattern

recognition.

o E-nose was first suggested by K. Persaud and

George Dodd of Warwick University in 1982.

o Then afterwards in 1988, another professor of this

university named Julian Gardner conducted his

research on this.

o It then came into popular use after 1989.

o Since then, development of sensor array-based

instruments has been actively pursued in Asia,

Europe and North America.

GC-MS measures about 250 volatile organic

compounds, but is time-consuming and expensive.

Dogs just indicate healthy / sick and do not provide

additional insight.

Human noses have too low sensitivity.

Electronic noses are fast and cheap, making them

suitable for mass screening.

The electronic nose was

developed in order to mimic

the human olfaction.

Essentially, e-nose consists of

three major parts:

o Sample Delivery System

o Detection System

o Computing system

o The sample delivery system enables the delivery of

sample( volatile compounds).

o The detection system, which consists of a sensor

set, is the “reactive” part of the instrument. 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.

o The computing system works to combine the

responses of all the sensors which represent the input

for the data treatment; it then performs analysis and

provides results.

o In a typical e-nose, an air sample is pulled by a vacuum

pump through a tube into a small chamber housing the

electronic sensor array.

o A sample-handling unit exposes the sensors to the

odorant, producing a response as the VOCs interact

with the active material.

o The sensor response is recorded and delivered to the

Signal-processing unit.

o Then a washing gas such as alcohol is applied to the

array for a few seconds or a minute, so as to remove

the odorant mixture from the active material.

Based on the type of sensors employed, e-nose can

be classified into the following categories:

o Conductivity Sensors

o Polymer Sensors

o Piezoelectric Sensors

o FET Gas Sensors

o Optical Sensors

The more commonly

used sensors include

• metal oxide

semiconductors (MOS),

• conducting polymers

(CP),

• quartz crystal

microbalance, surface

• acoustic wave (SAW),

and field effect

transistors.

SENSOR SET

IN E NOSE

BIO- NOSE E-NOSE

1. It uses the lungs to bring the odor to

epithelium layer.

2. It has mucus, membrane and hair to

act as filter.

2. The human nose contains the

olfactory epithelium, which

contains millions of sensing cells

that interact with the odorous

molecules in unique ways.

1. It employs a pump to

smell the odor.

2. It has an inlet sampling

system that provides

filtration.

3. E-nose has a variety of

sensors that interact

differently with the samples

provided.

BIO NOSE E-NOSE

4. The human receptors convert

the chemical responses to

electronic nerve impulses

whose unique patterns are

propagated by neurons

through a complex network

before reaching the higher

brain for interpretation.

4. Similarly, the chemical sensors

in the E-nose react with the

sample and produce electrical

signals. A computer reads the

unique pattern of signals, and

interprets them with some form

of intelligent pattern

classification algorithm.

•The Cyranose 320 is a

handheld “electronic

nose” developed by

Cyrano Sciences of

Pasadena, California in

2000.

•Applications researched

using the Cyranose 320

includes the detection of

COPD, and other medical

conditions as well as

industrial applications

generally related to

quality control or

contamination detection.

The applications(current) of an electronic nose include:

Medical diagnosis and health monitoring

Environmental monitoring

Application in food industry

Detection of explosives

Space applications(NASA)

In research and development industries

In quality control laboratories

In process and production department

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.

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 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.

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.

o Currently, this is the biggest market for e-nose.

Its applications include quality assessment in

food production and monitoring various food

items based on their odor.

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.

o The human sniffers are costly as compared to e-nose.

o Also detection of hazardous gases by them is not

possible.

o E-nose has wide range of sensitivity.

o Results obtained by e-nose are fast and more accurate.

o It is well- suited for repetitive or boring tasks.

o It can also detect substances which are not detected by

our human nose, like mercury.

o E-nose can only identify a standard set of odors

which is stored in its database.

o Though it is effective but still it can’t mimic the

complex human olfactory system exactly.

o They also have shorter lifetime because of the

sensors employed in them.

o Moreover, e-noses available in market are not

economical.

In the field of health and security:

o The quality control of food products as it could be

conveniently placed in food packaging to clearly

indicate when food has started to rot.

o It is used to detect bacterial contamination in the

food products.

o It can be used to detect the cancers like brain

and lung cancer.

o A more futuristic application of e-nose has been

recently proposed for telesurgery.

In the field of crime prevention:-

• The ability of the electronic nose to detect odorless

chemicals makes it ideal for use in the police force,

such as to detect drug odors despite other airborne

odors capable of confusing police dogs. However this

is unlikely in the mean time as the cost of the

electronic nose is too great and until its price drops

significantly it is unlikely to happen.

•It may also be used as a bomb detection method in

airports. Through careful placement of several or more

electronic noses and effective computer systems you

could triangulate the location of bombs to within a few

meters of their location in less than a few seconds

o An electronic nose is a system created to mimic the functioning

of human nose.

o Since the whole working is automatic, it can also be used by non

specialists.

o Although it has several advantages, yet it is still far from the

selectivity provided by a human nose.

o Basically, it is a tool provided to overcome the shortcomings of

human nose thus giving us more fast and accurate results.

o Future developments in the use of advanced sensor arrays and the

development of adaptive artificial neural networking techniques

will lead to superior electronic noses.

• http://en.wikipedia.org/wiki/Electronic_nose

• www.enose.info/environmental.html

• http://enose.jpl.nasa.gov

• http://science1.nasa.gov/2004/06oct_enose

• H. V. Shurmur, “The fifth sense: on the scent of

the electronic nose” IEEE Review, pp:- 59-98,

March 1990