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ELECTRONIC NOSE

By:- Naveen Sihag

B.Tech

Introduction An electronic nose is a device intended to detect

odors or flavours.

Over the last decades, “electronic sensing” or “e-sensing” technologies have undergone important development from a technical and commercial point of view.

Since 1992, researches have been conducted to develop technologies, commonly referred to as electronic nose that could detect and recognise odors and flavours.

Electronic noseElectronic nose

Contents E-sensing Techniques to analyze odors. Working Principle of Electronic Nose. How to perform an analysis. A range of applications. References.

What is e-sensing ?

“Electronic Sensing” refers to the capability of reproducing human senses using sensor arrays and pattern recognition systems.

Techniques to analyze odors

In industry, aroma assessment is usually In industry, aroma assessment is usually performed by gas chromatography. The performed by gas chromatography. The technique gives information about volatile technique gives information about volatile organic compounds but the correlation between organic compounds but the correlation between analytical results and actual odor perception is analytical results and actual odor perception is not direct due to potential interactions between not direct due to potential interactions between several odorous components.several odorous components.

The three major parts of electronic nose

A sample delivery system. A detection system. A computing system.

A sample delivery system

The sample delivery system enables the generation of the headspace (volatile compounds) of a sample, which is the fraction analyzed. The system then injects this headspace into the detection system of the electronic nose.

The sample delivery system is essential to guarantee constant operating conditions.

SAMPLE DELIVERYSAMPLE DELIVERY

The detection system The detection system, which consists of a sensor

set, is the “reactive” part of the instrument. When in contact with volatile compounds, the sensors react, which means they experience a change of electrical properties.

INFORMATION DETECTING INFORMATION DETECTING SYSTEMSYSTEM

The computing system The computing system works to combine the

responses of all the sensors which represent the input for the data treatment.

COMPUTING SYSTEMCOMPUTING SYSTEM

The sensors The most commonly used sensors are:-• MOS (Metal Oxide Semiconductors).• CP (Conducting Polymers).• MOSFET ( Metal Oxide Semiconductor Field

Effect Transistor).

MosMos

A metal oxide semiconductor structure is A metal oxide semiconductor structure is obtained by depositing a layer of silicon dioxide obtained by depositing a layer of silicon dioxide (SiO(SiO22) and a layer of metal on top of a ) and a layer of metal on top of a semiconductor die. As the silicon dioxide is a semiconductor die. As the silicon dioxide is a dielectric material its structure is equivalent to a dielectric material its structure is equivalent to a planar capacitor, with one of the electrode planar capacitor, with one of the electrode replace by a semiconductor.replace by a semiconductor.

MOSMOS

What is “MOSFET” ? It stand for metal oxide semiconductor field-effect

transistor. It is an important semiconductor device and is widely employed in many circuit application.

How to perform an analysis

An electronic nose needs to be trained with qualified samples so as to build a database

of reference. Then the instrument can recognize new samples by comparing volatile compounds fingerprint to those contained in its database, performing qualitative or quantitative analysis.

The applications The electronic nose instruments are used:-

1. In Research and Development laboratories.

2. In Quality Control laboratories.

3. Process and Production department.

In Research and Development laboratories:-

In the research & development laboratories, the electronic nose are used for:-

1. The formulation or reformulation of products.

2. Self life and stability studies.

3. Selection of raw materials.

4. Packaging interaction effects.

and so on..

In Quality Control labs.

In quality control laboratories, electronic nose are used for :-

1. Conformity of raw materials, intermediate and final products.

2. Batch to batch consistency.

3. Detection of contamination, spoilage, adulteration.

4. Monitoring of storage conditions.

and so on..

In Process and Production department

In process and production department, electronic nose is used for :-

1. Managing raw material variability.

2. Comparison with a reference product.

and so on..

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