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SMELL OF SUCCESS FOR NANO BIOSENSORS

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					     SMELL OF SUCCESS FOR NANO
          BIOSENSORS




                          D.Sowmya
                         (06-05-905)

INTERNAL GUIDE:Mrs.Sunitha Reddy
Introduction

   What is biosensor?
    An analyte is a substance or chemical constituent that is
    determined in an analytical procedure like while in blood
    glucose testing, the analyte is glucose

   A biosensor is a device for the detection of an analyte
    which that combines a biological component with a
    physicochemical detector component
What is smell of success for Nano
biosensors?
   Modern-day doctors may soon start using smell to detect
    the early warning signs of different illnesses thanks to
    technology that replicates - and improves upon - the human
    olfactory system thanks to tiny bioelectronic sensors.

   These nanobiosensors will react to a few molecules of
    odorant with a very high degree of accuracy . These tiny
    bioelectronics sensors represent a „major leap forward‟ in
    smell technology .
What is electronic nose?
   An electronic nose is a device intended to detect odors or
    flavors.

   Over the last decade, “electronic sensing” or “e-sensing”
    technologies have undergone important developments from
    a technical and commercial point of view. The expression
    “electronic sensing” refers to the capability of reproducing
    human senses using sensor arrays and pattern recognition
    systems
Why electronic nose?
   Think of the day when we can retire those
    dogs that go around sniffing bags and people
    for bombs or drugs, possibly irritating the
    people who are being targeted at. Instead,
    we have this machine overhead scanning and
    “sniffing” for bombs and drugs
     An electronic nose basically detects
    chemicals in the air, given off by odorous
    substances, and finds a pattern of the
    chemicals to determine what the smell in the
    air is.
Human smell system and molecules

    The olfatory system has mucus membrane which
    contains small segments, nerve cells, the actual sensory
    organs .
    The dendrites, some type of fiber, are covered from the
    nerve cells to nasal cavity with a thin layer of moisture.
   The smell particles are the source of what we smell.
    The moisture dissolves microscopic particles that are
    carried in by air from the odor-emitting substance to the
    nose The dissolved particles in the mucus stimulate the
    olfactory nerve cells through chemical reactions.
Electronic nose working principle
   A sample delivery system:enables the generation of the
    headspace (volatile compounds) of a sample, which is the
    fraction analyzed.
   A detection system:which consists of a sensor set, is the
    “reactive” part of the instrument. When in contact with
    volatile compounds, the sensors react.
   A computing system:works to combine the responses of
    all of the sensors, which represents the input for the data
    treatment
Performing analysis
   As a first step, an electronic nose need 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 databaseto perform analysis.
   Odour handling system
   Sensor array chamber
   Signal conditioning
   Data aquistion
   Signal processing
Block diagram
 Application
         At the space station-for detecting ammonia at few parts of
         million(ppm).
         Working:
        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-
     The Electronic nose smells something


 e-                                           e-
                e-            e-                                       e-
                                                           e-


      If a different compound had caused the air to change, the pattern of the
                  polymer films' change would have been different:




                              e-
e-                                             e-                      e-
                e-                                          e-
More applications
   These include with an example of using dogs to detect to sniff out
    bombs, drugs, or fugitives.
   Another useful usage of electronic noses is measuring environmental
    contamination and detect hazardous chemicals
    identifying chemical spills, diagnose strep infection, hunt for truffles,
    keep toast from burning, or detecting bad batches of food or drink .
    Currently we have humans to test for quality of foods, beverages,
    perfumes, tobaccos, washing powders, or even air quality, but using
    human testers is expensive and is prone to errors since human sense of
    smell may change with age, health, or diet
Cyrano Sciences

                     A company that currently
                      produces electronic noses
                      is Cyrano Sciences.
                      Cyrano Sciences makes
                      handheld electronic noses
                      that use a type of polymer
                      technology licensed from
                      California Institute of
                      Technology (CalTech )
Problems in development of e-nose
   Firstly classification of smell is based on subjective
    perception such as this odor smells fruity, which is
    imprecise .
    The second major problem is classification of the
    physiochemical properties describing each molecule will
    be huge .
   Smell composing of similar compounds with slightly
    different ratios of each of these compounds will result in a
    different smell .
   Ex:Coffee, tea, and cocoa all contain the same 670
    compounds with different ratios and to a normally
    functioning nose, each beverage drink smells differently.
Conclusion
   In conclusion, electronic noses can be very
    beneficial to our everyday life.
    . A more precise electronic nose might one day
    be used to “smell” viral or bacterial infections.
    With the development and usage better electronic
    noses, the days using dogs to sniff bombs and
    drugs passing through our airports will soon be
    over.
References
   http://science.nasa.gov/headlines/y2004/06oct_eno
    se.htm
   http://www.physorg.com/news66917655.html
   http://en.wikipedia.org/wiki/Electronic_nose
   cns-
    web.bu.edu/pub/laliden/WWW/Papers/nose.html
    www.e-nose.net/ProgressReport.htm

				
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posted:7/28/2011
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