1.E-NOSE

2. INTRODUCTION PREVIOUS WORK DONE WORKING OF E-NOSE E-NOSE VS. BIO NOSE APPLICATIONS ADVANTAGES CHALLENGES INVOLVED FUTURE ASPECTS CONCLUSION REFERENCES 3. An electronic nose is a device that identifies the specific components of an odor and analyzes its chemical makeup to find it. It consists of certain mechanisms such as an array of electronic sensors for chemical detection and artificial neural network for pattern recognition. 4. E-nose was first suggested by K. Persaud and George Dodd of Warwick University in 1982. Then afterwards in 1988, another professor of this university named Julian Gardner conducted his research on this. It then came into popular use after 1989. Since then, development of sensor array-based instruments has been actively pursued in Asia, Europe and North America. 5. The electronic nose was developed in order to mimic the human olfaction.Essentially, e-nose consists of three major parts: Sample Delivery System Detection System Computing system 6. The sample delivery system enables the delivery of sample( volatile compounds). 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 analysis and provides results. 7. 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. A sample-handling unit exposes the sensors to the odorant, producing a 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. 8. Based on the type of sensors employed, e-nose can be classified into the following categories: Conductivity Sensors Polymer Sensors Piezoelectric Sensors FET Gas Sensors Optical Sensors 9. CONDUCTIVITY SENSORS:These types of sensors exhibit a change in conductance when exposed to volatile organic compounds. POLYMER SENSORS :-Here the active material is a conducting polymer from such families as the Polypyrroles, thiophenes, indoles or furans. Changes in the conductivity of these materials occur as they are exposed to various types of chemicals, as certain reactions take place. 10. e-e-e-e-e-e-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. 11. e-e-e-e-e-e-Each polymer changes its size, and therefore its resistance, by a different amount, making a pattern of the change.e-ee-e-e-e-If a different compound had caused the polymer to change, the pattern of the polymer films' change would have been different. 12. PIEZOELECTRIC SENSORS:-A piezoelectric sensor is a device that uses the piezoelectric effect to measure any physical change like pressure, strain etc. Here, the gas adsorption leads to change in mass of the sensor . FET GAS SENSORS:Chemical FET(Field-effect transistor) is a type of a fieldeffect transistor acting as a chemical sensor. In this, the charge on the gate electrode is applied by a chemical process which may be used to detect atoms, molecules, and ions in liquids and gases . 13. OPTICAL SENSORS:These utilize glass fibers with a chemically active material coating on their sides or ends. A light source is used to interrogate the active material which responds with the change in color to the presence of VOCs. The active material contains chemically active fluorescent dyes. As the VOCs interact with it, the color of the fluorescent dye changes, hence lead to detection. 14. BIO- NOSEE-NOSE1. It uses the lungs to bring the odor to epithelium layer.1. It employs a pump to smell the odor.2. It has mucus, membrane and hair to act as filter.2. It has an inlet sampling system that provides filtration.3.The human nose contains 3. E-nose has a variety of the olfactory epithelium, sensors that interact which contains millions of differently with the sensing cells that interact with samples provided. the odorous molecules in unique ways. 15. BIO NOSE4.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.E-NOSE4. 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. 16. 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. 17. In environmental monitoring: For identification of volatile organic compounds in air, water and soil samples. For environmental protection. In quality control laboratories: Conformity of raw material, intermediate products. Detection of contamination, spoilage and adulteration. Monitoring of storage conditions.and final 18. For medical diagnosis:As the sense of smell is an important sense to the physician, an e-nose has applicability as a diagnostic tool. It can examine odors from the body and thus can identify possible problems. In food industry: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. 19. The human sniffers are costly as compared to e-nose. Also detection of hazardous gases by them is not possible. E-nose has wide range of sensitivity. Results obtained by e-nose are fast and more accurate. It is well- suited for repetitive or boring tasks. It can also detect substances which are not detected by our human nose, like mercury. 20. E-nose can only identify a standard set of odors which is stored in its database. Though it is effective but still it cant mimic the complex human olfactory system exactly. They also have shorter lifetime because of the sensors employed in them. Moreover, e-noses available in market are not economical. 21. In the field of health and security: The quality control of food products as it could be conveniently placed in food packaging to clearly indicate when food has started to rot. It is used to detect bacterial contamination in the food products. It can be used to detect the cancers like brain and lung cancer. A more futuristic application of e-nose has been recently proposed for telesurgery. 22. 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 23. An electronic nose is a system created to mimic the functioning of human nose. Since the whole working is automatic, it can also be used by non specialists. Although it has several advantages, yet it is still far from the selectivity provided by a human nose. Basically, it is a tool provided to overcome the shortcomings of human nose thus giving us more fast and accurate results.Future developments in the use of advanced sensor arrays and the development of adaptive artificial neural networking techniques will lead to superior electronic noses. 24. 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:- 5998, March 1990