This document discusses biosensors, including their structure, history, working principles, types, sensing elements, transducers, amplifiers, and applications. It defines a biosensor as a device that combines a biological component with a physicochemical detector to detect analytes. The key components are a biological recognition element, transducer to convert the biological response into a measurable signal, and amplifier. Major applications mentioned include glucose monitoring, environmental monitoring, drug discovery, and food/agriculture testing. Disadvantages include inability to use heat sterilization and stability issues with biological materials.

1. Biosensors
Structure & Application
Presented by:
MR. TARUN KAPOOR
Asst. Prof.
Shri Ram College of Pharmacy,
Karnal

2. Contents
1. Sensor and Transducer
2. Biosensor
3. History of Biosensor
4. Working principle of Biosensor
5. Types of Biosensor
6. Sensing elements in Biosensor
7. Transducer
8. Amplifier
9. Applications
10. Disadvantages

3. Sensor & transducer
• A Sensor is an object whose purpose is to detect events or changes in its
environment, and then provide a corresponding output. e.g Pressure sensor,
Ultrasonic sensor, Humidity Sensor, Gas Sensor, Motion Sensor,
Biosensor, Acceleration sensor, Displacement sensor etc.
• A Transducer is a device that converts one form of energy to another. e.g
pressure sensor might detect pressure (a mechanical form of energy) and
convert it to electrical signal for display at a remote gauge.
• A sensor is a type of transducer.

4. Biosensor
• Biosensors are analytical tools for the analysis of bio-material
samples to understand their bio-composition, structure and
function by converting a biological response into an electrical
signal. Example: Enzyme- conductometric biosensor for
blood-glucose monitoring.
• A biosensor is an analytical device, used for the detection of
an analyte, that combines a biological componentwith a
physicochemical detector.

5. History of Biosensor
• Professor Leland C Clark Jnr is known as the father of the
biosensor . On 15 April 1956 the biosensor that he invented
was named after him as “Clark electrode”(measured oxygen
level in blood).
• 1975 Clark’s ideas became commercial reality with the
successful re-launch of the Yellow Springs Instrument
Company (Ohio) glucose analyser based on the amperometric
detection of H2O2
• 1977 Karl Cammann introduced term biosensor

6. Working Principal of
Biosensor
1. Biological reorganization of elements which is highly specific
towards the biological material analytes products.
2. Transducers detect the transduces signal from biological
receptor targets to electrical to reaction signal which is due
occur.
3. After transduction signal from biological to electrical signal
where its amplification is necessary and takes place and read
out in detector after processing the values are displayed for
monitor and controlling the system.

8. Types of Biosensors
• Piezoelectric Sensors
• Calorimetric/Thermal Detection Biosensors
• Optical Sensors
• Electrochemical Sensors
o Conductometric Sensors
o Amperometric Sensors
o Potentiometric Sensors
CONTD.

9. • Piezoelectric Sensors: Piezoelectric biosensors are considered as mass-
based biosensors. Piezoelectric biosensors are based on the principle of
acoustics (sound vibrations), hence they are also called as acoustic
biosensors. Piezoelectric biosensors produce an electrical signal when a
mechanical force is applied .Example of piezoelectric sensor is quartz
crystal micro or nano balance.
• Calorimetric/Thermal Detection Biosensors: It works on the principal of
absorption/ production of heat.
• Optical Sensors: The optical fibers allow detection of analytes on the basis
of absorption, fluorescence or light scattering. The reaction causes a
change in fluorescence or absorbance resulting due to change in the
refractive index of the surface between two media which differ in density.
For Example, if antibodies bind on a metal layer, the refractive index of the
medium in contact with this layer will change.
• Electrochemical Biosensors: Electrochemical Biosensors are integrated
receptor-transducer devices capable of providing selective and quantitative
analytical information using a biological recognition element.
CONTD.

10. • Electrochemical Biosensors: Electrochemical Biosensors are
integrated receptor- transducer devices – capable of providing
selective and quantitative analytical information using a biological
recognition element. A biomolecule is immobilized onto an
electrode that has been modified by coating it with an electronically
conducting, semiconducting, or ionically conducting chemical.
Coating materials that have been used include electrochemically
prepared polyaniline and polypyrrole films, or other conducting
polymers.
• Conductimetric Sensors: Conductometric biosensors measure
changes in the conductivity
• of a medium as a result of enzyme reactions that change its ionic
composition.
• Amperometric Sensors: Amperometric biosensors measure the
electric current associated with electron flow resulting from redox
reactions.
• Potentiometric Sensors: Potentiometric biosensors use ion
selective electrodes to determine changes in the concentration of
chosen ions.

11. SENSING ELEMENTS
1. Enzymes are proteins with high catalytic activity and selectivity towards
substrates . They have been used for decades to assay the concentration of
diverse analytes. Their commercial availability at high purity levels makes
them very attractive for mass production of enzyme sensors. Enzymes have
been immobilized at the surface of the transducer by adsorption, covalent
attachment, entrapment in a gel or an electrochemically generated polymer, in
bilipid membranes or in solution behind a selective membrane. Enzymes are
commonly coupled to electrochemical and fiber optic transducers.
CONTD.

12. Antibodies
• Antibodies are proteins that show
outstanding selectivity. Molecules
larger than about 10kDa can
stimulate an immune response.
• Many antibodies are commercially
available and commonly used in
immunoassays. Antibodies are
usually immobilized on the surface
of the transducer by covalent
attachment by conjugation of
amino, carboxyl, aldehyde, or
sulfhydryl groups. The surface of
the transducer must be previously
functionalized with an amino,
carboxyl, hydroxyl, or other
group.
CONTD.

13. Micro-organisms
• The use of micro-organisms as biological elements in
biosensors is based on the measurement of their metabolism.
Microbial cells have the advantage of being cheaper than
enzymes or antibodies,
• can be more stable, and can carry out several complex
reactions involving enzymes and cofactors. Conversely, they
are less selective than enzymes, they have longer response and
recovery times, and may require more frequent calibration.
CONTD.

14. TRANSDUCING ELEMENTS
(Principle of detection)

15. AMPLIFIER
• An amplifier, is an electronic device that increases
the power of a signal
Power amplifier
Transistors amplifier
Operational amplifier

16. APPLICATIONS
• Glucose monitoring , pregnancy test in diabetes patients historical market
driver
• Environmental applications e.g. the detection of pesticides and river water
contaminants such as heavy metal ions
• Remote sensing of airborne bacteria e.g. in counter-bioterrorist activities
• Remote sensing of water quality in coastal waters by describing online
different aspects of clam ethology (biological rhythms, growth rates,
spawning or death records) in groups of abandoned bivalves around the
world
• Determining levels of toxic substances before and after bioremediation
• Routine analytical measurement of folic acid, biotin, vitamin B12 and
pantothenic acid as an alternative to microbiological assay
• Drug discovery and evaluation of biological activity of new compounds
• Detection of toxic metabolites such as mycotoxins
• Detecting levels of toxins in an ecosystem
• Detecting airborne pathogens (i.e. anthrax)
• Monitoring blood glucose levels

17. GLUCOSE MONITORING
IN BLOOD

18. IN AGRICULTURE,FOOD
INDUSTRY
• DETECTION OF VIRAL FUNGAL BACTERIAL DISEASE
OF PLANTS
• DETECTION OF FOOD, TOTAL MICROBES IN SOFT
DRINKS
• DETERMINE FRESHNESS OF FRUIT,MEAT,FISH ETC.
• OPTICAL BIOSENSOR USES CYANIDE TO
• GLOW BACTERIAAND DETECT IT

19. Tattoo biosensor warns when
athletes are about to ‘hit the wall

20. Disadvantages
1. Heat sterilization is not possible because of denaturaization
of biological material.
2. Stability of biological material (such as enzyme, cell,
antibody, tissue, etc.), depends on the natural properties of
the molecule that can be denaturalized under environmental
conditions (pH, temperature or ions).
3. The cells in the biosensor can become intoxicated by other
molecules that are capable of diffusing through the
membrane
4. Fabrication is Costly