12-12-2012, 01:58 PM
Mid Examination seminar on CONDUCTING POLYMER IN SENSORS
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How a polymer moves from electrical insulator to electrical conductor ?
Polymers are organic molecules made from carbon, nitrogen,oxygen,hydrogen with covalent bonds .These covalent bonds are not suppose to electrically conductive ,because there is not free electrons. So polymers are not conductor.
e.g. human brain haves conducting part like neurons ,pulses to measure the electrical conductivity.
Similarly organic molecules also can transmit electricity & current, although there is no free electron.
That means there is such type of mechanism which provides electrical conduction. If we make some free electron in polymer then it can behave as conducting polymer. So organic molecule called synthetic metal which have free electron ,by which conduct electricity and current.
In intrinsic materials when some donar & acceptor puts some defects ,means materials takes electrons from system or donates electrons to the system. In that way it defect some materials and that help to conductivity in semiconductor materials.
This concept has extended to polymer materials also.
Conducting Polymer in Sensor
Conducting polymer are novel porous organic semiconductor materials which have attracted considerable attention because of there remarkable optical,electrochemical,and conducting properties.
Among various conducting polymers polyaniline (PANI)has attracted significant attention because it exhibits environmental stability and its electrical properties can be tuned by varying the oxidation state and protonation state.
Nano structured PANI application:
Gas separation membrane.
polymeric conducting molecular wires
light emitting electronic devices
Biosensors
Chemical sensors
In neuron sensing devices.
Biosensors
A biosensor is an analytical device for the detection of an analyte that combines a biological component with a physicochemical detector.
Biosensors consists of biorecognition system.Typically enzyme or binding proteins such as antibodies ,immobilised on to the surface of physico chemical transducer.
A term immunosensor(senses the immune system) is often used to described biosensors which use antibodies their biorecognition.
Antibodies : an antibody known as immunoglobulin , is a large Y shaped protein produced by B-cell that is used by immune system to identified and neutralize foreign object such as bacteria and viruses.
Bacteria : bacterias are a large domain of microorganism ,in µm range.These shapes ranging from spheres to rods and spirals.
PANI In Biosensor
Among the polycongugated polymers has been recently
proposed for biosensing application ,because of a no. of
favourible characterstics such as-
Direct and easy deposiion on sensor electrode by electrochemical oxidation of monomer.
Control of thickness.
Conducting polymer have application in amperometric enzyme electrode with the intention to couple the electron transfer reaction between enzyme and electrode via the conductive network of polymer.
Example: Polyaniline,Polypyrrole , Poly(o-anisidine) , Poly(o-toluidine).
Immobilization of enzyme on electrode
Immobilization of enzyme on electrode materials is achieved by physical and chemical methods and covalent coupling.
Immobilization means ,that enzymes while retaining their catalytic activity is confined with in certain space or bound to solid carriers.
Glucose oxides has been the most frequently used molecular recognition element, called enzyme, due to it’s high binding spacificity,high reaction rate and relative stability.so enzyme in conducting polymer provides accurate control of polymer thickness through electrical charge passed during film formation.
[attachment=43513]
How a polymer moves from electrical insulator to electrical conductor ?
Polymers are organic molecules made from carbon, nitrogen,oxygen,hydrogen with covalent bonds .These covalent bonds are not suppose to electrically conductive ,because there is not free electrons. So polymers are not conductor.
e.g. human brain haves conducting part like neurons ,pulses to measure the electrical conductivity.
Similarly organic molecules also can transmit electricity & current, although there is no free electron.
That means there is such type of mechanism which provides electrical conduction. If we make some free electron in polymer then it can behave as conducting polymer. So organic molecule called synthetic metal which have free electron ,by which conduct electricity and current.
In intrinsic materials when some donar & acceptor puts some defects ,means materials takes electrons from system or donates electrons to the system. In that way it defect some materials and that help to conductivity in semiconductor materials.
This concept has extended to polymer materials also.
Conducting Polymer in Sensor
Conducting polymer are novel porous organic semiconductor materials which have attracted considerable attention because of there remarkable optical,electrochemical,and conducting properties.
Among various conducting polymers polyaniline (PANI)has attracted significant attention because it exhibits environmental stability and its electrical properties can be tuned by varying the oxidation state and protonation state.
Nano structured PANI application:
Gas separation membrane.
polymeric conducting molecular wires
light emitting electronic devices
Biosensors
Chemical sensors
In neuron sensing devices.
Biosensors
A biosensor is an analytical device for the detection of an analyte that combines a biological component with a physicochemical detector.
Biosensors consists of biorecognition system.Typically enzyme or binding proteins such as antibodies ,immobilised on to the surface of physico chemical transducer.
A term immunosensor(senses the immune system) is often used to described biosensors which use antibodies their biorecognition.
Antibodies : an antibody known as immunoglobulin , is a large Y shaped protein produced by B-cell that is used by immune system to identified and neutralize foreign object such as bacteria and viruses.
Bacteria : bacterias are a large domain of microorganism ,in µm range.These shapes ranging from spheres to rods and spirals.
PANI In Biosensor
Among the polycongugated polymers has been recently
proposed for biosensing application ,because of a no. of
favourible characterstics such as-
Direct and easy deposiion on sensor electrode by electrochemical oxidation of monomer.
Control of thickness.
Conducting polymer have application in amperometric enzyme electrode with the intention to couple the electron transfer reaction between enzyme and electrode via the conductive network of polymer.
Example: Polyaniline,Polypyrrole , Poly(o-anisidine) , Poly(o-toluidine).
Immobilization of enzyme on electrode
Immobilization of enzyme on electrode materials is achieved by physical and chemical methods and covalent coupling.
Immobilization means ,that enzymes while retaining their catalytic activity is confined with in certain space or bound to solid carriers.
Glucose oxides has been the most frequently used molecular recognition element, called enzyme, due to it’s high binding spacificity,high reaction rate and relative stability.so enzyme in conducting polymer provides accurate control of polymer thickness through electrical charge passed during film formation.