18-02-2010, 01:12 PM
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INTRODUCTION
¢ A biosensor is a device for the detection of an analytic that combines a biological component with a physicochemical detector component. Many optical biosensors based on the phenomenon of surface plasmon resonance are evanescent wave techniques . The most widespread example of a commercial biosensor is the blood glucose biosensor, which uses the enzyme glucose oxidase to break blood glucose down
Biosensor consist of
¢ 1.the sensitive biological element
¢ 2.the transducer or detector element
¢ 3.signal processors
SUCCESSFUL FEATURES
¢ Durable
¢ Tiny and compactable
¢ Linear response
¢ Small, cheap
¢ Easy use
¢ Highly specific
WORKING PRINCIPLE
a “ analyte
b-interferent
c - immobilized biological molecule
d -biospecific immobilization surface
e - chemical signal
f- transducer
g - amplification and control unit interferent
h - output of measured analyte
ADVANTAGES
1.Less sensitive
2.Long life
3.Cheap
4.More tolerant
DISADVANTAGES
Response time is longer
After use it require more time
Cells contains many enzymes
APPLICATIONS
1.Medicine and health
2.Industry
3.Military
4.Pollution control
TYPES
1. Potentiometric biosensors
2. Amperometric biosensors
3. Optimal biosensors
4. Calorimetric biosensors
5. Acoustic wave biosensors
POTENTIOMETRIC BIOSENSOR
¢ Use iron selective electrodes
¢ Electrodes used are
-solid state electrode
-ph meter glass electrode
¢ Gas sensing electrode detect and measure the amount of gas produced
CALORIMETRIC BIOSENSORS
¢ It measures the change in temperature
¢ It can be used for turbid and strongly colored solutions
¢ Eg-glucose oxidase for determination of glucose
AMPEROMETRIC BIOSENSORS
¢ Production of current when potential applied between electrodes
¢ These are the first generation biosensors
¢ Used to measure redox reactions
OPTICAL BIOSENSORS
¢ Measure both catalytic and affinity reactions
¢ They measure change in fluorescence
ACOUSTIC WAVE BIOSENSORS
¢ These are also called piezo electric devices
¢ There Surface is coated with antibodies which bind to the complementary antigen present in the sample solution
FUTURE DIRECTIONS
There are number of areas where the unique capabilities of biosensors might be exploted to meet the requirement of environmental monitering.advances in such areas such as toxity,bioavailability and multipollutant screening, could when the potential market and allow these techniques to be more competetive.miniatarizaion,reversability and continuous operation may allow biosensor techniques to be incorporated as detectors in chromatographic systems
