This document provides an overview of biosensors, including their main components, working principle, types, applications, and future directions. It discusses how biosensors work by using a bioreceptor to interact with an analyte, which is then measured by a transducer and outputs a proportional signal. The main types described are calorimetric, potentiometric, acoustic wave, amperometric, and optical biosensors. Applications highlighted include use in food analysis, medical diagnosis like glucose monitoring, drug development, and environmental monitoring. Nanobiosensors and lab-on-a-chip technologies are also summarized as areas of ongoing research to improve biosensor sensitivity, size, and versatility.

1. BIOSENSORS
BY HASNAT TARIQ

2. CONTENTS
 INTRODUCTION
 MAIN COMPONENTS OF A BIOSENSOR
 WORKING PRINCIPLE
 FEATURES OF A BIOSENSOR
 TYPES OF BIOSENSOR
 APPLICATIONS OF BIOSENSOR
 NANOBIOSENSORS
 EXAMPLE OF NANOBIOSENSOR
 LAB ON A CHIP
 APPLICATIONS OF LAB ON A CHIP
 EXAMPLE OF BIOSENSORS WITH THEIR WORKING
 FUTURE OF BIOSENSORS 2

3. INTRODUCTION
• A biosensor is an analytical device
containing an immobilized biological
material (enzyme, antibody, nucleic
acid, hormone, organelle or whole
cell) which can specifically interact
with an analyte and produce physical,
chemical or electrical signals that can
be measured. An analyte is a
compound (e.g. glucose, urea, drug,
pesticide) whose concentration has to
be measured.
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4. MAIN COMPONENTS OF A BIOSENSOR
• Sensor
• Transducer
• Amplifier
• Processor
• Display unit
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5. • Sensor
It is a sensitive biological element (biological material (eg. tissue,
microorganisms, organelles, cell receptors, enzymes, antibodies,
nucleic acids, etc).
• Transducer
Transducer is a device that converts energy from one form to
another form. In biosensors transducers convert the biochemical
activity into electrical energy.
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7. WORKING PRINCIPLE
• Biosensors are operated based on the principle of signal
transduction.
• Bioreceptor, is allowed to interact with a specific analyte. The
transducer measures this interaction and outputs a signal. The
intensity of the signal output is proportional to the concentration of
the analyte. The signal is then amplified and processed by the
electronic system.
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8. FEATURES OF A BIOSENSOR
a) It should be highly specific for the analyte.
b) The reaction used should be independent of manageable factors
like pH, temperature, stirring, etc.
c) The response should be linear over a useful range of analyte
concentrations.
d) The device should be tiny and bio-compatible.
e) The device should be cheap, small, easy to use and capable of
repeated use.
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9. TYPES OF BIOSENSOR
1. Calorimetric Biosensors
2. Potentiometric Biosensors
3. Acoustic Wave Biosensors
4. Amperometric Biosensors
5. Optical Biosensors
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10. 1. Calorimetric Biosensor
Many enzyme catalysed reactions are exothermic, generating
heat which may be used as a basis for measuring the rate of reaction
and, hence, the analyte concentration.
The analyte solution is passed through a small packed bed
column containing immobilized enzyme; the temperature of the
solution is determined just before entry of the solution into the column
and just as it is leaving the column using separate thermistors.
An example is the use of glucose oxidase for determination of
glucose.
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11. 2. Potentiometric Biosensors
These biosensors use ion-selective electrodes to convert the
biological reaction into electronic signal.
Many reactions generate or use H+ which is detected and
measured by the biosensor.
Urea Biosensor is an example of these biosensors.
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12. 3. Acoustic Wave Biosensors (Piezoelectric Biosensors)
Acoustic sensors use piezoelectric materials, typically quartz
crystals, in order to generate acoustic waves.
Their surface is usually coated with antibodies which bind to
the complementary antigen present in the sample solution.
This leads to increased mass which reduces their vibrational
frequency; this change is used to determine the amount of antigen
present in the sample solution.
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13. 4. Amperometric Biosensors
Amperometric biosensors function by the production of a
current when a potential is applied between two electrodes.
The magnitude of current being proportional to the substrate
concentration.
These biosensors are used to measure redox reactions.
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14. 5. Optical Biosensors
These involve determining changes in light absorption between
the reactants and products of a reaction, or measuring the light
output by a luminescent process.
A most promising biosensor involving luminescence uses
firefly enzyme luciferase for detection of bacteria in food or clinical
samples.
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15. APPLICATIONS OF BIOSENSOR
• Food analysis
• Study of Biomolecules and their
interactions
• Drug development
• Crime detection
• Medical diagnosis
• Environmental field monitoring
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• Industrial process control
• Manufacturing of
pharmaceuticals and
replacement of organs
• Monitoring glucose level in
diabetes patients
• Protein engineering
• Wastewater treatment
• Agriculture industry

16. • Biosensors in Food Industry
Biosensors are used for the detection of pathogens in food.
Presence of Escherichia coli in vegetables, is a bioindicator of faecal
contamination in food. E. coli has been measured by detecting
variation in pH caused by ammonia (produced by urease–E.
coli antibody conjugate) using potentiometric alternating biosensing
systems.
Enzymatic biosensors are also employed in the dairy industry.
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17. • Biosensors in Medical field
Glucose biosensors are widely used in clinical applications for
diagnosis of diabetes mellitus.
A novel biosensor, based on hafnium oxide (HfO2), has been
used for early stage detection of human interleukin.
These are also used for detection of cardiovascular diseases.
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18. • Biosensors in Drug Discovery and Drug Analysis
Enzyme‐based biosensors can be applied in the pharmaceutical
industry for monitoring chemical parameters in the production
process (in bioreactors).
Affinity biosensors are suitable for high‐throughput screening of
bioprocess‐produced antibodies and for drug screening.
Oligonucleotide‐immobilized biosensors for interactions studies
between a surface linked DNA and the target drug or for hybridisation
studies.
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19. • Role of Biosensors in Environmental Monitoring
The biosensors find wide application for measurement,
estimation and control of water, air and soil contaminants.
Determination of the pesticides can be made by
potentiometric biosensor.
Amperometric basic sensor can be used for analyses of water
pollution from herbicide.
Concentration of ammonia can be defined with microbe
biosensor with cells of type Nitrosomonas sp.
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20. • Epigenetics
Photonic biosensors have been developed, which can detect
tumor cell in a urine sample to an ultra-sensitivity level .
Epigenetic modifications are detected after exploitation of
integrated optical resonators (e.g., post-translational modifications in
histone and DNA methylation) using body fluids of patients suffering
from cancer or other ailments.
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21. NANOBIOSENSORS
• Advances in nanotechnology have led to the development of
nanoscale biosensors that have exquisite sensitivity and versatility.
• The ultimate goal of nanobiosensors is to detect any biochemical
and biophysical signal associated with a specific disease at the level
of a single molecule or cell.
• They can be integrated into other technologies such as lab-on-a-
chip to facilitate molecular diagnostics.
• Their applications include detection of microorganisms in various
samples, monitoring of metabolites in body fluids and detection of
tissue pathology such as cancer.
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23. Advantages of Nanobiosensor
 Enhanced sensitivity
 Reduced instrumentation size
 Improved Speed and specificity in biodiagnostics.
 Low cost
 Reduction in sensor size provides great versatility for incorporation
into multiplexed, transportable, wearable, and even implantable
medical devices.
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24. Disadvantage of Nanobiosensor
 The major problem is that the biomolecule is turned into a colloid
by attaching it to a nanocrystal. Because colloids have very different
‘solubility’ from biomolecules, there is always a tendency for
coagulation within biological media.
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25. EXAMPLE OF NANOBIOSENSOR
• Nanowire Biosensors
Major sensing components are
made of nanowires coated by biological
molecules such as DNA molecules,
polypeptides, fibrin proteins, and
filamentous bacteriophages.
The nanomaterials transduce the
chemical binding event on their surface
into a change in conductance of the
nanowire in an extremely sensitive,
real time and quantitative fashion.
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26. LAB ON A CHIP
• A lab on a chip (LOC) is a device
that integrates one or several
laboratory fucntions on a single
chip of only few millimeters to a
few square centimeters in size.
• Basically, LOC integrate
microfluidics, nanosensors,
microelectrics, biochemistry and
electronic components on the
same chip.
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27. APPLICATIONS OF LAB ON A CHIP
• Concentration gradient
generator
• Electrophoretic separator
• Microbio-reactor •PCR chip
for DNA amplification
• Quantitative DNA sensor chip
(capable of detecting single-
pair mismatch)
• Flow cytometer Lab-on-a-Chip
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• Immunoassay Lab-on-a-
Chipforbacteria(e.g., E.coli, H.
pylori) detection
• Real-Time PCR detection chips
(fordetecting E. coli, cancers, etc)
• Blood sample preparation Lab-on-
a-Chip
• Cellular analysis Lab-on-a-Chip
• Microarrays“(Biochips) DNA
microarrays, Protein microarrays

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29. Use of LOC In HIV detection
• 40 million people are infected with HIV..
• 1.3 million of these people receive anti-retroviral treatment. Around 90%
of people with HIV have never been tested for the disease.
• Measuring the number of CD4+ T lymphocytes in a person’s blood is an
accurate way to determine if a person has HIV.
• At the moment, flow cytometry is the gold standard for obtaining CD4
counts
• Recently such a cytometer was developed for just $5.
• In such devices it is possible to quickly diagnose and potentially treat
diseases.
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30. Use of LOC for Plant Studies
• Lab-on-a-chip devices could be used to characterize pollen
tube guidance.
• Specifically, plant on a chip is a miniaturized device in which pollen
tissues and ovules could be incubated for plant sciences studies.
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32. HOW GLUCOSE BIOSENSOR WORKS?
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33. FUTURE OF BIOSENSORS
• Biosensor Technology Will Detect—and Potentially Prevent—Illness
• Biosensor Technology is on the Verge of Changing how Diabetics
Monitor Their Glucose Levels
• Biosensor Technology Could Put an End to Drunk Driving
• Greater use of nanotechnology and microfluidics (LAB N A CHIP)
• Intelligent control of medication delivery
• Greater use of home-based monitoring and treatment
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36. THANK YOU
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