Biosensors are analytical devices that measure the concentration of an analyte using a biological material like an enzyme, antibody, or nucleic acid. The biological material interacts with the analyte and produces a physical or chemical change detected by a transducer, which converts it into an electrical signal proportional to the analyte concentration. Biosensors can be classified based on their transducer, such as electrochemical, optical, thermal, and piezoelectric biosensors. They have applications in medical diagnostics, environmental monitoring, food safety testing, and more due to their sensitivity, specificity, and ability to provide rapid, real-time results.

1. BIO SENSORS
TYPES AND APPLICATIONS

2. WHAT ARE BIO SENSORS ?
• These are analytical devices, which measure concentration of analyte
• In bio sensors , a biology material ( such as enzyme , antibody, whole
cell , nucleic acid, DNA or RNA) is used to interact with the analyte.
• This interaction produces a physical or chemical change , which is
detected by the transducer and converted to an electrical signal
• This signal is then interpreted and converted to analyte concentration
present in the sample.

3. • What is biological sensor?
• A typical biosensor usually comprises of a biosensing element
and a transducer.
• It has various biological applications and is used for the
detection of several components such as pollutants,
microbial load, metabolites, control parameters, and
various other substances

4. FROM NET
• Biosensors can be classified according to the mode of
physicochemical transduction or the type of biorecognition
element.
• Based on the transducer, biosensors can be classified as
electrochemical, optical, thermal, and piezoelectric
biosensors [10]
• Electrochemical biosensors [11] can be further classified as
amperometric biosensors (that measure the current produced
during oxidation or reduction of electroactive product or
reactant),

5. • potentiometric biosensors (that measure the potential of the
biosensor electrode with respect to a reference electrode), and
conductometric biosensors (that measure the change in
conductance arising due to the biochemical reaction).
• Electrochemical biosensors are the most extensively
investigated biosensors as they offer the advantage of low
detection limit, specificity, simplicity of construction, and ease
of operation.
• Owing to recent advances in electronic instrumentation, these
biosensors can be miniaturized as lab-on-chip devices for in
vivo monitoring or as handheld device for on-site
monitoring [11].

6. • Optical biosensors rely on measurement of light absorbed or
emitted as a consequence of a biochemical reaction.
• Optical biosensors are based on various optical techniques
such as absorption, fluorescence, luminescence, surface
plasmon resonance (SPR), etc. [12]. Among these, the
colorimetric biosensors are extensively explored due to ease of
detection of the visible color change shown by these

7. • Biosensors have been widely researched and developed as a
tool for medical, environmental, food, and pharmaceutical field.
The biosensors are designed to produce a digital electronic
signal which is proportional to the concentration of a specific
biochemical or a set of biochemicals in the presence of a
number of interfering species

8. • Because of utilization of biofunctionalities such as recognition
and catalysis, those are called “bio”sensors.1
• The typical architecture of biosensors is a combination of
biological components and transducers.
• In those, amperometric enzyme biosensors, which are
composed by enzyme as a biological substance and electrode
as a transducer, are one of the most popular biosensors.
• The fact that the output signal is current makes the design of
measurement circuit simple and the sensitivity higher, when
comparing to potentiometric biosensors.

9. • A key technology in developing the amperometric enzyme
biosensors is how well the enzymes are combined to the
surface of the electrodes.
• The performance of the enzyme biosensors is dominated by the
combination technique of these two components.2
• In more explanation, the sensitivity and dynamic range are
determined by the efficiency that the electronic signal due to
enzymatic detection transfers to the electron collector
(electrode).
• This technique is often called “enzyme immobilization.” Here,
enzyme immobilization chemistry for biosensors is described.

10. • Biosensors, due to their immense potential in medical
diagnostics, have driven scientific research to enhance the
development of biosensor technologies that can surpass
conventional in vitro diagnostics for disease detection and
health monitoring.
• Aptamer-based biosensors (aptasensors) can detect a wide
range of targets (e.g., small molecules, ions, and vitamins and
large molecules like proteins and whole cells)

11. • What is a Biosensor?
• Biosensors can be defined as analytical devices which include a
combination of biological detecting elements like a sensor
system and a transducer.
• When we compare with any other presently existing diagnostic
device, these sensors are advanced in the conditions of
selectivity as well as sensitivity.
• The applications of these Biosensors mainly include
checking ecological pollution control, in the agriculture field as
well as food industries. The main features of biosensors are
stability, cost, sensitivity, and reproducibility.

12. • The short form of the biological sensor is known as a biosensor.
In this sensor, a biological element is maybe an enzyme, a
nucleic acid otherwise an antibody.
• The bio-element communicates through the analyte being
checked & the biological reply can be changed into an electrical
signal using the transducer.
• Based on the application, biosensors are classified into
different types like resonant mirrors, immune, chemical
canaries, optrodes, bio-computers, glucometers & biochips.

13. • Main Components of a Biosensor
• The block diagram of the biosensor includes three segments
namely, sensor, transducer, and associated electrons.
• In the first segment, the sensor is a responsive biological part,
the second segment is the detector part that changes the
resulting signal from the contact of the analyte, and for the
results, it displays in an accessible way.
• The final section comprises an amplifier which is known as a
signal conditioning circuit, a display unit as well as the
processor.

15. • Working Principle of Biosensor
• Usually, a specific enzyme or preferred biological material is
deactivated by some of the usual methods, and the deactivated
biological material is in near contact with the transducer.
• The analyte connects to the biological object to shape a clear
analyte which in turn gives the electronic reaction that can be
calculated.
• In some examples, the analyte is changed to a device that may be
connected to the discharge of gas, heat, electron ions, or hydrogen
ions. In this, the transducer can alter the device linked convert it into
electrical signals which can be changed and calculated

16. • Working of Biosensors
• The electrical signal of the transducer is frequently low and
overlays upon a fairly high baseline.
• Generally, the signal processing includes deducting a position
baseline signal, obtained from a related transducer without any
biocatalyst covering.

17. • The comparatively slow character of the biosensor reaction
significantly eases the electrical noise filtration issue.
• In this stage, the direct output will be an analog signal however
it is altered into digital form and accepted to a
microprocessor phase where the information is progressed,
influenced to preferred units, and o/p to a data store.

18. • Example
• Before discussing the different types of biosensors and their uses,
we have to discuss the simple example of this biosensor like
Glucometer.
• This is most frequently used in different medical applications. We
know that diabetes is one of the dangerous diseases that
characterize the glucose levels within the blood of human bodies.
• So for diabetes patients, checking glucose levels within the blood is
essential.
• For that, a glucometer is used as a biosensor to measure the
glucose concentration within the human blood.
Generally, a glucometer includes a strip for testing.

19. • This strip collects the blood sample and checks the glucose
level within the blood.
• This strip includes a trigger as well as a reference-type
electrode.
• Once a blood sample is poured on the strip, then a chemical
reaction takes place to generate an electrical current that is
directly proportional to the glucose concentration.
• The processor used in the glucometer is Cortex-M3 otherwise
Cortex-M4 through the flow of current toward filter, amplifier,
voltage converter, a display unit.

20. • Types of Biosensors
• The different types of biosensors are classified based on the
sensor device as well as the biological material that is
discussed below

21. • Electrochemical Biosensor
• Generally, the electrochemical biosensor is based on the
reaction of enzymatic catalysis that consumes or generates
electrons.
• Such types of enzymes are named Redox Enzymes. The
substrate of this biosensor generally includes three electrodes
such as a counter, reference, and working type.

23. • he object analyte is engaged in the response that happens on
the surface of an active electrode, and this reaction may source
also electron transfer across the dual-layer potential.
• The current can be calculated at a set potential.

24. • Electrochemical biosensors are classified into four types
• Amperometric Biosensors
• Potentiometric Biosensors
• Impedimetric Biosensors
• Voltammetric Biosensor

25. • Amperometric Biosensor
• An amperometric biosensor is a self-contained incorporated
device based on the amount of the current ensuing from the
oxidation offering exact quantitative analytical information.
• Generally, these Biosensors have reaction times, energetic
ranges & sensitivities comparable to the Potentiometric-
biosensors.
• The simple amperometric biosensor infrequent usage includes
the “Clark oxygen” electrode.

27. • The rule of this biosensor is based on the amount of the flow of
current between the Counter Electrode and the working which is
encouraged by a redox response at the operational electrode.
• Choosing analyte centers is essential for a wide selection of
uses, comprising high-throughput medicine screening, quality
control, problem finding and handling, and biological checking.

28. • Potentiometric Biosensor
• This type of biosensor provides a logarithmic reply by means of
a high energetic range.
• These biosensors are frequently complete by monitor producing
the electrode prototypes lying on a synthetic substrate, covered
by a performing polymer with some enzyme is connected.

30. • They comprise two electrodes that are enormously responsive
and strong. They allow the recognition of analytes on stages
before only attainable by HPLC, LC/MS & without exact model
preparation.
• All types of biosensors generally occupy the least sample
preparation because the biological detecting component is
extremely choosy used for the analyte troubled.
• By the changes of physical and electrochemical the signal will
be generated by in the layer of conducting polymer due to
modifying happening at the outside of the biosensor.

31. • These changes might be credited to ionic force, hydration, pH, and
redox responses, the latter as the label of enzyme rotating above a
substrate.
• In FETs, the gate terminal has been changed with an antibody or
enzyme, which can also sense very-low attention from different
analytes because the required analyte toward the gate terminal
makes a modify in the drain to source current.
• The main types of potentiometric biosensors are ISE or Ion-
Selective Electrodes based on the membrane, ISFET (Ion-Selective
Field Effect Transistors), Solid state devices, Screen-Printed
Electrodes & modified electrodes through chemically like metal
oxides otherwise electrodeposited polymers like sensitive layers.

32. • Enzyme Biosensor
• This sensor is one kind of analytical device, used to merge an
enzyme using a transducer to generate a signal that is proportional
to the concentration of the target analyte. Further, this signal can be
amplified, stored, processed for later analysis.
• DNA Biosensor
• The development of DNA biosensors can be done based on
identification techniques of nucleic acid for analysis of simple, rapid
& economical testing of genetic & infectious diseases.
• Also, the exact DNA series detection is important in several areas
like food analysis, clinical, environmental, etc. For better detection
techniques, SAM & SELEX technologies are used for developing
better recognition techniques for DNA Biosensors.

33. • Different from antibodies or enzymes, recognition of nucleic
acid layers can be willingly created & regenerate for several
uses.
• As compared to normal hybridization, these sensors, as well as
gene chips, have many benefits because of their enormous
potential for attaining specific data in a simpler, cheaper & faster
manner.
• Further, these sensors have been increased but, the
fundamental investigation is still required to enhance the sensor
technologies, detecting plans, instrumentations for analytical &
procedures

34. • Immunosensors
• Immuno sensors were recognized on the truth that antibodies
include high affinity to their particular antigens like the
antibodies particularly combine to toxins or pathogens or
interact through host immune system’s components.
• These types of biosensors are based on affinity ligand solid-
state devices where the reaction of immunochemical can be
connected to a transducer.

35. • Biosensors Applications
• Biosensor devices include a biological element as well as a
physiochemical detector and the main function of this device is to
detect analytes.
• So, the applications of biosensors are in a wide range. These
devices are applicable in the medical, food industry, the marine
sector as they offer good sensitivity & stability as compared with the
usual techniques.
• In recent years, these sensors have become very popular, and they
are applicable in different fields which are mentioned below.
•

37. • Common healthcare checking
• Metabolites Measurement
• Screening for sickness
• Insulin treatment
• Clinical psychotherapy & diagnosis of disease
• In Military
• Agricultural, and Veterinary applications
• Drug improvement, offense detection
• Processing & monitoring in Industrial
• Ecological pollution control
• Diagnostic & Clinical
• Industrial & Environmental Applications
• Study & Interaction of Biomolecules

38. • Development of Drug
• Detection of Crime
• Medical Diagnosis
• Monitoring of Environmental Field
• Quality Control
• Process Control in Industries
• Pharmaceuticals Manufacturer & Organs Replacement

39. • Biosensors act as analytical devices to detect biological materials.
• The wide use of enzymes, proteins, nucleic acids and other such
biomolecules makes it possible.
• The main aim is to detect whether a particular chemical, compound, microbe
or any such component is present or not in the given sample.
• This helps a lot in various detection procedures including those of toxic
compounds in the environment, food, drugs and also nowadays in forensic
sciences, used as a tool for crime detection.

40. • Forensics is making use of the biosensors for detecting the biomolecules and
biological components found at the crime scenes which may play a great role
in identifying the suspect and even reaching the criminal.
• Different components like fingerprints, blood samples, odour act as a
detecting elements for biosensors.
• Biosensors are also used in lie detection procedures, to know whether the
suspect is telling the truth or not.
• All these detection processes involve use of different and specific type of
biosensors which are discussed here.

41. • Biosensors can play a great role in enhancing the procedures
of crime detection. The field of forensic sciences will have a
new way to detect and find out the criminal in a more efficient
and accurate manner.
• The use of various different biosensors for detecting different
type of biological components generally found at crime scenes
will help to get good results in less time.
• More biosensors may also be developed keeping in mind, the
expected samples and their complement molecules so that it
can be detected in an efficient manner.

42. • Not only that but biosensors could also be used in forensics as a tool for
crime detection.
• Forensics is making use of biosensors to detect the biomolecules and organic
additives determined on the crime scenes, which can also play a role in
figuring out the suspect or even reaching the criminal [355].
• Different additives like fingerprints, blood samples, and odors act as detecting
factors for biosen-sors

43. BIO SENSORS

44. DIAGRAMATIC REPRESENTATION OF BIO SENSOR
• Transducer is present in the for of a strip, Biological component
shown in green is attached or absorbed
• Analyte shown in red interacts with the biological components
• Interaction produces either a physical or chemical change which is
detected by the transducer.
• This change is convetered into an electrical signal which is amplified
by the amplifier.
• Amplified electrical signal is then processed by the processor and
converted into analyte concentration present in the solution.
• This is displayed on the screen of the bio sensor.

45. TYPES OF BIO SENSORS
• 1. CARORIMENTRIC BIO SENSORS
• They measure change in temperature due to either release
(exothermic) or absorption (endothermic) of heat (reaction) example
temperature bio sensors
• 2. POTENTIOMETRIC BIO SENSOR
• They measure potential difference arising from a redox reaction
example Urea bio sensor
• AMPEROMETRIC BIO SENSOR
• They measure current (flow of electrons) arising during a reaction
example Glucose bio sensor

46. • CONDUCTOMETRIC BIO SENSOR
• They measure changes in electrical conductivity arising during a
reaction example Uria bio sensor
• ACUASTIC WAVE BIO SENSOR
• They measure electric field developed by piezoelectric effects
example cocaine bio sensor
• OPTICAL BIO SENSOR
• They measure light arising from the action of enzymes luciferace
obtained from fire flies example detection of bacteria

47. PROPERTIES OF A BIO SENSOR
• Highly specific for the analyte
• The response should be linear over a broad substrate range
• The device should be small and bio compatible
• It should be low cost , small and easy to use
• Assay cost should be lower than conventional tests
• Assay should be fast , reliable and repeatable