The document provides a comprehensive overview of biosensors, detailing their basic components, working principles, types, and applications. A biosensor combines a biological element with a transducer to detect specific analytes, converting biological responses into measurable electrical signals. Applications range from food safety monitoring to glucose level detection in diabetes management.

1. Himanshu Kamboj
Assistant Professor

2. CONTENTS
▪ Introduction
▪ Basic components of Biosensor
▪ Working of Biosensor
▪ Types of Biosensor
▪ Applications of Biosensor

3. • A sensor is a converter that measures a physical quantity
and converts it into a signal which can be read by an
observer or by an instrument.
• Nanosensors are any biological, chemical, or surgical
sensory points used to convey information about
nanoparticles to the macroscopic world.
 medicinal purposes
nanoproducts, such as computer chips that work at the
nanoscale and nanorobots.
INTRODUCTION

4. INTRODUCTION
• A biosensor is a sensing device comprised of a combination
of a specific biological element and a transducer.
• A “specific biological element” recognizes a specific
analyte and the changes in the biomolecule are usually
converted into an electrical signal (which is in turn
calibrated to a specific scale) by a transducer.
• It detects, records, and transmits information regarding a
physiological change or process.
• It determines the presence and concentration of a
specific substance in any test solution.

5. Father of the Biosensor Professor Leland C Clark Jnr
(1918–2005 )
• A device incorporating a biological sensing element
either intimately connected to or integrated within a
transducer.
• Recognition based on affinity between complementary
structures like enzyme-substrate, antibody-antigen and
receptor-hormone complex.
• Selectivity and specificity depend on biological
recognition systems connected to a suitable transducer.
• It is an analytical device which converts a biological
response into an electrical signal.
• It detects, records, and transmits information regarding
a physiological change or process.

6. BASIC PRINCIPLE OF
BIOSENSOR
• The biological material is immobilized and a contact is
made between the immobilized biological material and the
transducer
• The analyte binds to the biological material to form a bound
analyte which in turn produces the electronic response that
can be measured.
• Sometimes the analyte is converted to a product which
could be associated with the release of heat, gas (oxygen),
electrons or hydrogen ions. The transducer then converts
the product linked changes into electrical signals which can
be amplified and measured

7. COMPONENTS
▪ Bio-element
▪ Transducer component

8. BIO-ELEMENT
It is a typically complex chemical system usually extracted
or derived directly from a biological organism.
Types :
• Enzymes
• Oxidase
• Polysaccharide
• Antibodies
• Tissue
• Nucleic Acid

9. ▪ Function :- To interact specifically with a target compound i.e.
the compound to be detected.
▪ It must be capable of detecting the presence of a target
compound in the test solution.
▪ The ability of a bio-element to interact specifically with target
compound (specificity) is the basis for biosensor.
BIO-ELEMENT

10. TRANSDUCER
▪ Function :
To convert biological response in to an electrical
signal.
▪ Types :
Electrochemical
Optical
Piezoelectric

11. DETECTOR
Signals from the transducer are passed to a microprocessor
where they are amplified and analyzed. The data is then
converted to concentration units and transferred to a display
or/and data storage device.
PRINCIPLE OF DETECTION
• PIEZOELECTRIC: Measures change in mass
• ELECTRO-MECHANICAL: Measures change in
electric distribution
• OPTICAL: Measures change in light intensity
• CALORIMETRIC: Measures change in heat

12. WORKING OF
BIOSENSOR
Figure:- Schematic Diagram of a Biosensor

13. • Biosensors basically involve the quantitative analysis of
various substances by converting their biological actions
into measurable signals.
• Generally the performance of the biosensors is mostly
dependent on the specificity and sensitivity of the
biological reaction, besides the stability of the enzyme

14. RESPONSE FROM BIO-ELEMENT
■ Heat absorbed (or liberated ) during the interaction.
■ Movement of electrons produced in a redox reaction.
■ Light absorbed (or liberated ) during the interaction.
■ Effect due to mass of reactants or products.

15. IDEAL BIOSENSOR
• The output signal must be relevant to measurement environment.
• The functional surface must be compatible with the transducer.
• High specificity and selectivity (low interference).
• Sufficient sensitivity and resolution
• Sufficient accuracy and repeatability
• Sufficient speed of response
• Sufficient dynamic range.
• Insensitivity to environmental interference or their effects must
be compensated

16. ADVANTAGES
• Highly Specific.
• Independent of Factors like stirring, pH, etc.
• Linear response, Tiny & Biocompatible.
• Easy to Use, Durable.
• Require only Small Sample Volume.
• Rapid, Accurate, Stable & Sterilizable.

17. BASIC CHARACTERESTICS
• LINEARITY - Should be High - For the detection
of High Substrate Concentration.
• SENSITIVITY - Value of Electrode Response per
Substrate Concentration.
• SELECTIVITY - Chemical Interference must be
minimised for obtaining Correct Result.
• RESPONSE TIME – Time necessary for having
95% of the Response.

18. TYPES OF BIOSENSOR
▪ Electrochemical biosensor
▪ Optical biosensor
▪ Thermal biosensor
▪ Resonant biosensor
▪ Ion-sensitive biosensor

19. ELECTROCHEMICAL
BIOSENSORS
▪ Principle
Many chemical reactions produce or consume ions or
electrons which in turn cause some change in the electrical
properties of the solution which can be sensed out and
used as measuring parameter.
▪ Classification
(1) Amperometric Biosensors
(2) Conductimetric Biosensors
(3) Potentiometric Biosensors
continue…

20. AMPEROMETRIC BIOSENSORS
▪ This high sensitivity biosensor can detect electro-active
species present in biological test samples.
▪ Since the biological test samples may not be intrinsically
electro-active, enzymes are needed to catalyze the
production of radio-active species.
▪ In this case, the measured parameter is current.

21. CONDUCTIMETRIC
BIOSENSORS
■
■
■ The measured parameter is the electrical
conductance / resistance of the solution.
When electrochemical reactions produce ions or
electrons, the overall conductivity or resistivity of the
solution changes. This change is measured and
calibrated to a proper scale(Conductance measurements
have relatively low sensitivity.).
The electric field is generated using a sinusoidal
voltage (AC) which helps in minimizing undesirable
effects such as Faradaic processes, double layer
charging and concentration polarization.

22.  Uses Absorption / Production of Heat.
 Total heat produced/absorbed is ᾶ Molar Enthalpy/Total
No. of molecules in the rn.
 Temp. measured by Enzyme Thermistors.
Advantages:
• No need of Frequent recalibration.
• Insensitive to the Optical & Electrochemical
• Properties of the sample.
Uses:
Detection of: (1) Pesticides .
(2) Pathogenic Bacteria.

23. POTENTIOMETRIC
BIOSENSORS
• In this type of sensor the measured parameter is
oxidation or reduction potential of an electrochemical
reaction.
• The working principle relies on the fact that when a
ramp voltage is applied to an electrode in solution, a
current flow occurs because of electrochemical
reactions.
• The voltage at which these reactions occur indicates a
particular reaction and particular species.

24. OPTICAL-DETECTION
BIOSENSORS
• The output transduced signal that is measured is light for this type of
biosensor.
• The biosensor can be made based on optical diffraction.
• In optical diffraction based devices, a silicon wafer is coated with a
protein via covalent bonds. The wafer is exposed to UV light through
a photo-mask and the antibodies become inactive in the exposed
regions.
• When the diced wafer chips are incubated in an analyte, antigen-
antibody bindings are formed in the active regions, thus creating a
diffraction grating.
• This grating produces a diffraction signal when illuminated with a
light source such as laser.
• The resulting signal can be measured.

25. THERMAL-DETECTION
BIOSENSORS
 This type of biosensor work on the fundamental properties
of biological reactions, namely absorption or production of
heat, which in turn changes the temperature of the medium
in which the reaction takes place.
 They are constructed by combining immobilized enzyme
molecules with temperature sensors. When the analyte
comes in contact with the enzyme, the heat reaction of the
enzyme is measured and is calibrated against the analyte
concentration.
 The total heat produced or absorbed is proportional to the
molar enthalpy and the total number of molecules in the
reaction.

26.  The measurement of the temperature is typically
accomplished via a thermistor, and such devices
are known as enzyme thermistors. Their high
sensitivity to thermal changes makes
thermistors ideal for such applications.
 Unlike other transducers, thermal biosensors do
not need frequent recalibration and are
insensitive to the optical and electrochemical
properties of the sample.
 Common applications of this type of biosensor
include the detection of pesticides and
pathogenic bacteria.

27. RESONANT BIOSENSORS
■ It Utilize crystals which undergo an elastic deformation
when an electrical potential is applied to them.(Alternating
potential (A.C.) produces a standing wave in the crystal at
a characteristic frequency.)
In this type of biosensor, an acoustic wave transducer is
coupled with an antibody (bio-element).
When the analyte molecule (or antigen) gets attached to
the membrane, the mass of the membrane changes. The
resulting change in the mass subsequently changes the
resonant frequency of the transducer. This frequency
change is then measured.
■
■

28. ION-SENSITIVE BIOSENSORS
• These are semiconductor FETs having an ion-sensitive
surface.
• The surface electrical potential changes when the ions and
the semiconductor interact.(This change in the potential
can be subsequently measured.)
• The Ion Sensitive Field Effect Transistor (ISFET) can be
constructed by covering the sensor electrode with a
polymer layer. This polymer layer is selectively permeable
to analyte ions. The ions diffuse through the polymer layer
and in turn cause a change in the FET surface potential.
• This type of biosensor is also called an ENFET (Enzyme
Field Effect Transistor) and is primarily used for pH
detection.

29. GLUCOSE BIOSENSORS
 Glucose reacts with glucose oxidase(GOD) to form
gluconic acid. Two electrons & two protons are also
produced.
 Glucose mediator reacts with surrounding
oxygen to form H2O2 and GOD.
Now this GOD can reacts with more glucose.
Higher the glucose content, higher the oxygen
consumption.
Glucose content can be detected by Pt-electrode.

31. APPLICATIONS OF
BIOSENSORS
▪ In food industry, biosensors are used to monitor the
freshness of food.
▪ Drug discovery and evaluation of biological activity of
new compounds.
▪ Potentiometric biosensors are intended primarily for
monitoring levels of carbon dioxide, ammonia, and other
gases dissolved in blood and other liquids.
▪ Environmental applications e.g. the detection of pesticides
and river water contaminants.

32. ▪ Determination of drug residues in food, such as antibiotics
and growth promoters.
▪ Glucose monitoring in diabetes patients.
▪ Analytical measurement of folic acid, biotin, vitamin B12
and pantothenic acid.
▪ Enzyme-based biosensors are used for continuous
monitoring of compounds such as methanol, acetonitrile,
phenolics in process streams, effluents and groundwater.
▪ Detection of viral, fungal, bacterial diseases of plants.
▪ In food industry, detection of total microbes & food
quantification in soft drinks.
▪ To determine the freshness of other fish, beef & other
food items.
▪ Makes Bacteria GLOW by OPTICAL Biosensor

33. THANK YOU