A PRESENTATION ON ELECTRONIC NOSE PRESENTED BY vivek gangwar ELECTRONICS & COMMUNICATION

~ INTRODUCTION ~ SMELL ORGANS IN LIVING BEINGS ~ ARTIFICIAL SMELL TECHNIQUES ~ WORKING PRINCIPLE OF E NOSE ~ VARIOUS TYPES OF SENSORS ~ MORE ON WORKING…. ~ RANGE OF APPLICATIONS ~ CREDITS.

INTRODUCTION ~WHAT IS AN E NOSE? ~ WHY E NOSE? ~ WHAT IS ODOUR? ~ WHAT ARE VOC’S? ~ WHAT ARE RECEPTORS?

ELECTRONIC 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

ODOUR ~odour in a substance is due to VOC’S or volatile Organic compounds which evaporate and get carried Away by air RECOGNITION ~receptors in human nose act as binding sites for VOC’S these voc’s are then processed by brain and We recognise the smell.

MAIN COMPONENTS OF E NOSE  SENSING SYSTEM  PATTERN RECOGNITION SYSTEM  SUB  SUB COMPONENTS  SAMPLE DELIVERY SYSTEM  DETECTION SYSTEM  COMPUTING SYSTEM

 The sample delivery system enables the generation of the headspace (volatile compounds) of a sample. More on working  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.  The computing system works to combine the responses of all the sensors which represent the Input for the data treatment,it then performs global finger print analysis and provides results

BLOCK DIAGRAM

SCHEMATIC DIAGRAM

WORKING OF E NOSE  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.The tube may be of plastic or stainless steel.  A sample-handling unit exposes the sensors to the odorant, producing a transient response as the VOCs interact with the 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 array for a few seconds or a minute,so as to remove the odorant mixture from the active material.

INTRODUCTION 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 a sensor is illustrated by the following scheme : In the field of sensors, the correct definition of parameters is of paramount importance because of these parameters: ~allow the diffusion of more reliable information among researchers or sensor operators, ~allow a better comprehension of the intrinsic behavior of the sensors help to propose new standards, give fundamental criteria for a sound evaluation of different sensor performances. The output signal is the response of the sensor when the sensitive material undergoes modification

TYPES 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

Conductivity 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 Sensors Here 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.

All of the polymer films on a set of electrodes (sensors) start out at a measured resistance, their baseline resistance. If there has been no change in the composition of the air, the films stay at the baseline resistance and the percent change is zero e-e- e-e- e-e- e-e- e-e- e-e- BASELINE RESISTANCE.

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 SOMETHING e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e-

Optical Fiber Sensors  These utilize glass fibers with a thin chemically active material coating on their 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.  The active material contains chemically active fluorescent dyes immobilized in an Organic polymer matrix. As VOCs interact with it, the polarity of the fluorescent emission spectrum changes. Advantages: Cheap and easy to fabricate. Arrays of fiber sensors have wide range of sensitivities. Differential measurement is possible to avoid common mode noise. Disadvantages: Complexity of the measuring system.

Range of applications  It is used in research & development laboratories  It is used in quality control laboratories  Its is used in process and production departments of various companies.  able to detect tiny amounts of explosives

 Formulation or reformulation of products  Benchmarking with competitive products  Shelf life and stability studies  Selection of raw materials  Packaging interaction effects  Simplification of consumer preference test In R&D LABORATORIES

In Quality Control laboratories In Quality Control laboratories :  Conformity of raw materials, intermediate and final products  Batch to batch consistency  Detection of contamination, spoilage, adulteration  Origin or vendor selection  Monitoring of storage conditions.

 Measurement and comparison of the effects of manufacturing process on products  Following-up cleaning in place process efficiency  Scale-up monitoring  Managing raw material variability  Comparison with a reference product  Cleaning in place monitoring. In process and production departments for:

QUERIES?