Biosensors merge life sciences and engineering to detect specific analytes via immobilized biological materials, producing measurable signals. The document outlines the historical development, components, working principles, and various types of biosensors, including electrochemical, piezoelectric, and optical sensors. Applications span clinical diagnostics, industrial processes, environmental monitoring, agriculture, and food quality control.

1. Basic concepts of BIOSENSORS
Hritika Sharma IBT sem2
Asu2023010200079 , BSBT227
Submitted to : Ms Mishika Ahuja

2. What are biosensors?
Biosensors is an amalgamation of two disciplines ,
life sciences and engineering
Bio (living organisms) + sensors (to detect some kind
of activity)
A Biosensor is a measurement instrument that
contains an immobilized biological material (enzyme,
antibody, nucleic acid, hormone, organelle, or
complete cell) that can interact with an analyte and
produce physical, chemical, or electrical signals.

3. Origins of Biosensors
• The origins of biosensors dates back to 1906 when M. Cremer
demonstrated that the concentration of an acid in a liquid is
proportional to the electric potential that arises between parts of
the fluid located on opposite sides of a glass membrane.
• Between 1909 and 1922, Griffin and Nelson first demonstrated
immobilisation of the enzyme invertase on aluminium hydroxide
and charcoal.
• The first ‘true’ biosensor was developed by Leland C. Clark, Jr in
1956 for oxygen detection. He is known as the ‘father of biosensors’
and his invention of the oxygen electrode bears his name: ‘Clark
electrode’

4. COMPONENTS OF A BIOSENSOR
The major parts of a
Biosensor include:
1. Analyte/ bioagents
2. Bioreceptor
3. Transducer
4. Electronics
5. Display
Every biosensor comprises:
A biological component that acts as
the sensor
An electronic component that
detects and transmits the signal

5. ANALYTE
A substance of interest that must be discovered is called as analyte.
In a biosensor that is designed to detect glucose, so here, glucose is an
‘analyte.’
Some examples of analytes that are used are :
• Biosensors based on blood are used to detect blood components such as
glucose.
• In comparison to invasive blood-based biosensors, saliva-based biosensors
are steadily gaining acceptance for glucose measurement. These can also be
used to measure levels of lactate and cortisol, among other substances.
• Sweat-based biosensors can detect levels of chemicals like glucose, lactate,
ascorbic acid, and uric acid.
• Urine-based biosensors can detect levels of compounds like glucose, lactate,
ascorbic acid, and uric acid.

6. Bioreceptors
A bioreceptor is a molecule that recognizes the analyte
specifically. Bioreceptors include enzymes, cells,
aptamers, deoxyribonucleic acid (DNA), and antibodies.
Bio-recognition is the process of signal creation (in the
form of light, heat, pH, charge, or mass shift, etc.) when a
bioreceptor interacts with an analyte.

7. TRANSDUCERS
A transducer is a component that transforms one form of
energy into another. The transducer’s job in a biosensor is to
turn a bio-recognition event into a quantifiable signal.
Signalization is the name for energy conversion process. The
number of analytes–bioreceptor interactions is usually
proportionate to the amount of optical or electrical signals
produced by most transducers.

8. ELECTRONICS
This is the section of a biosensor that processes
and prepares the transduced signal for display.
It is made up of complicated electronic circuitry
that performs signal conditioning functions such as
amplification and digital signal conversion.
The display device of the biosensor then quantifies
the processed signals.

9. DISPLAY
Display is often made up of a combination of
hardware and software that delivers user-friendly
biosensor results.
Depending on the end user’s needs, the output
signal on the display can be numeric, visual,
tabular, or a picture.

10. Schematic representation of a Biosensor

11. Basic principle
The desired biological material (usually a specific
enzyme) is immobilized by conventional methods
(physical or membrane entrapment, non- covalent
or covalent binding). This immobilized biological
material is in intimate contact with 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.
In some instances, the analyte is converted to a
product which may be associated with the release of
heat, gas (oxygen), electrons or hydrogen ions.
The transducer can Convert the product linked
changes into electrical signals which can be
amplified and measured.

12. WORKING
The signal processing normally involves
1) subtracting a 'reference' baseline signal, derived from a similar
transducer without any biocatalyst membrane, from
the sample signal
2) amplifying the resultant signal difference
3) electronically filtering (smoothing) out the
unwanted signal noise.
The relatively slow nature of the biosensor response considerably
eases the problem of
electrical noise filtration. The analogue signal produced at this stage
may be output directly but is usually converted
to a digital signal and passed to a microprocessor stage where the
data is processed, manipulated to desired units and
output to a display device or data store

13. Types of biosensors
1) 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. Here molecules set up mechanical vibrations that
can be translated into an electrical signal proportional to
the amount of
the analyte.
Example of piezoelectric sensor is quartz crystal micro or
nano balance.

14. 2) Electrochemical Sensors:
These biosensors have been the subject of basic as well as
applied research for nearly fifty years. Leland C. Clark
introduced the principle of the first enzyme electrode with
immobilized glucose oxidase at the New York Academy of
Sciences Symposium in 1962.
In this configuration, sensing molecules are either coated
onto or covalently bonded to a probe surface. The sensing
molecules react specifically with compounds to be
detected, sparking an electrical signal proportional to the
concentration of the analyte. The electrochemical
biosensors can employ potentiometric, amperometric
and impedimetric transducers converting the chemical
information into a measurable amperometric signal

15. 3) Optical Sensors:
In optical biosensors, the optical fibers allow detection of analytes
on the basis of absorption, fluorescence or light
scattering. Here both catalytic and affinity reactions can be
measured.
Since they are non-electrical, optical biosensors
have the advantages of lending themselves to in
vivo applications and allowing multiple analytes to
be detected by using different monitoring
wavelengths.
The Versatility of fiber optics probes is due to their
capacity to transmit signals that reports on
changes in wavelength, wave propagation, time,
intensity, distribution of the spectrum, or polarity
of the light.

16. Via Researchgate.net

17. Applications of biosensors
The advantages of biosensors include low cost, small size, quick and
easy use, as well as a sensitivity and selectivity greater than the
current instruments. Biosensors have many uses in clinical analysis,
general health care monitoring.
1. Clinical and Diagnostic Applications:
Among wide range of applications of
biosensors, the most important
application is in the field of medical
diagnostics. The electrochemical
variety is used now in clinical
biochemistry laboratories for
measuring glucose and Lactic acid.

18. 2) Industrial Applications: Along with conventional industrial
fermentation producing materials, many new products are being
produced by large-scale bacterial and eukaryotes cell culture. The
monitoring of these delicate and expensive processes is essential
for minimizing the costs of production;
specific biosensors can be designed to measure the generation of
a fermentation product.
3) Environmental Monitoring: Environmental water monitoring is
an area in which whole cell biosensors may have substantial
advantages for combating the increasing number of pollutants
finding their way into the groundwater systems and hence into
Drinking water.
Important targets for pollution biosensors now include anionic
pollutants such as nitrates and
phosphates.

19. 4) Agricultural industries: Enzyme biosensors based on the
inhibition of cholinesterases have been used to detect traces of
organophosphates and carbamates from pesticides.
However, the only commercially available biosensors for
wastewater quality control are biological oxygen demand (BOD)
analyzers based on micro-organisms like the bacteria Rhodococcus
erythropolis Immobilized in collagen or polyacrylamide
5) Food industry: Biosensors for the measurement of carbohydrates,
alcohols, and acids are commercially available. Potential applications
of enzyme based biosensors to food quality control include
measurement of amino acids, amines, amides, heterocyclic
compounds, carbohydrates, carboxylic acids, gases, cofactors,
Inorganic ions, alcohols, and phenols. Biosensors can be used in
industries such as wine beer, yogurt, and soft drinks producers.

20. THANK YOU