The document discusses biosensors, which combine a biological component with a physicochemical detector. It defines biosensors as analytical devices used to detect analytes. The basic components of a biosensor are a biological recognition element, transducer to convert the biological response into an electrical signal, and a detector. Common types of biosensors include electrochemical, optical, piezoelectric, and ion-sensitive biosensors. The document also outlines the basic principles, components, characteristics, and applications of biosensors.

1. BIOSENSOR
ARYA H

2. • Father of Biosensor – Professor Leland C
Clark
• The term ‘biosensor’ is short for “biological
sensor”
• Analytical device used for the detection of
an analyte, that combines a biological
component with a physicochemical detector.
• It is a device incoporating a biological
sensing element either intimately connected
to or integrated within a transducer

3. • 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.

4. • It converts a response into an electrical signal
• It detects, records, and transmits information regarding a
physiological change or process
• It determines the presence and concentration of a specific
substance in an test solution
• Main features of biosensors are
stability
cost
sensitivity
reproducibility

5. Basic principle of biosensor
• Basic principle involved in three element :-
o First biological recognition element which highly specific towards
the biological material analytes produces
o Second transducers detect and transduces signal from biological
target – receptor molecule to electrical signal which is due to
reaction occur
o Third 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

7. Components of biosensors

8. Ist component – Biological element
• The component used to bind the target molecule
• Must be highly specific, stable under storage conditions and
immobilized
• A variety of substance may be used as bioelement in
biosensor
 Microorganism
 Tissue, Cell, Organelle
 Nucleic acid
 Enzyme, Enzyme component
 Receptor
 Antibody
 Plant proteins or lectins

9. • Functions;
 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 with target compound
(specificity) in the basis of biosensor

10. 2nd component – Physiochemical
Transducer
• Acts as an interface, measuring the physical change that
occurs with the reaction at the bioreceptor then transforming
that energy into measureable electrical output

11. 3rd component - 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

13. • The block diagram of biosensor include
three segments namely sensor, transducer
and associated electrons.
• In the first segment the sensor is a
responsive biological part
• 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 accesible way
• The final section comprises of an amplifier
which is known as signal conditioning circuit,
the display unit as well as the processor.

14. 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 inturn 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,
hydrogen ions.
• The transducer then converts the product linked changes into
electrical signals which can be amplified and measured

15. Working principle of Biosensor
 Analyte diffuses from the solution to the surface of the
biosensor
 Analyte reacts specifically and efficiently with the biological
component of the biosensor
 This reaction changes the physicochemical properties of the
transducer surface
 This leads to a change in the optical/ electronic properties of
the transducer surface
 The changes in the optical/ electronic properties is measured/
converted into electrical signal, which is detected

16. • 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 to 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 which
may be connected to the discharge of gas, heat, electron ions
or hydrogen ions
• In this the transducer can alter the device linked converts into
electrical signals which can be changed and calculated

18. How does they work…??
• Basically it 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

19. Ideal Biosensor
1. The output signal must be relevant to measurement
enviornment
2. The functional surface must be compatible with the
transducer
3. High specificity and sensitivity (low interference)
4. Sufficient sensitivity and resolution
5. Surface accuracy and repeatability
6. Sufficient speed of response
7. Sufficient dynamic range
8. Intensivity to enviornmental interference or their effects
must be compensated

20. Basic characteristics of Biosensor
1. LINEARITY – linearity of the sensor should be high for the
detection of high substrate concentration
2. SENSITIVITY – Value of the electrode response per substrate
concentration
3. SELECTIVITY – Chemicals interference must be minimised for
obtaining the correct result
4. RESPONSE TIME – Time necessary for having 95% of the
response

21. Typical Sensing Techniques
 Fluorescence
 DNA Microarray
 SPR (Surface Plasma Resistance)
 Impedance Spectroscopy
 SPM (Scanning Probe Microscopy)
 QCM (Quartz Crystal Microbalance)
 SERS (Surface Enhanced Raman Spectroscopy)

22. Types
 Calorimetric / Thermal Detection Biosensors
 Optical Biosensors
 Resonant Biosensors
 Piezoelectric Biosensors
 Ion Sensitive Biosensors
 Electrochemical Biosensors
* Conductimetric Sensors
* Amperometric Sensors
* Potentiometric Sensors

23.  Calorimetric / Thermal Detection Biosensors
 Uses Absorption / Production of heat
 Total heat produced / absorbed is α Molar Enthalpy / Total
No. of molecules in the run
 Tem. Measured by Enzyme Thermistors
Advantages
• No need of frequent recalibration
• Intensitive to the optical and electrochemical properties of
the sample
Uses
• Detection of : (1) Pesticides
(2) Pathogenic bacteria

24.  Ion Sensitive Biosensors
 Surface electrical potential changes when the ion and
semiconductor interact
 Measures the change in potential
 Uses
 Detection of pH
 Electrochemical Biosensors
 Many chemical runs produce or consume ions or electrons causing
some change in the electrical properties of the solution that can be
sensed out and used as a measuring parameter
 Uses
 Detection of :- (1) hybridized DNA
(2) DNA binding drugs
(3) glucose concentration

25.  Optical Biosensors
 Colorimetric for colour – Measure change in light adsorption
 Photometric for light intensity – Detects the photon input
 Resonant Biosensors
• An Acoustic Wave Transducer is coupled with bioelement
• Measures the change in Resonant Frequency
 Piezoelectric Biosensors
• Uses gold – To detect specific angle at which electron waves
are emitted when the substance is exposed to laser light/
crystals like quartz, which vibrates under the influence of an
electric field
• Change in frequency α Mass of absorbed material

26.  Conductimetric Sensors
 Measures electrical conductance / resistance of the solution
 Measurement has low sensitivity
 Electrical voltage is generated using sinusoidal (ac) voltage,
which helps in minimizing undesirable effects like :
i) Faradiac processes
ii) Double layer charging
iii) Concentration polarization
 Amperometric Biosensors
 High sensitivity
 Detects the electroactive species present in the biological test
samples
 Measured parameter – current

27.  Potentiometric Sensors
 Working principle – when voltage is applied to an electrode in
solution a current flow occurs because of electrochemical
reactions
 Measured parameter – oxidation / reduction potential of an
electrochemical run

28. Applications
• Food analysis
• Study of biomolecules and their interaction
• Drug development
• Crime detection
• Medical diagnosis (both clinical and laboratory use)
• Enviornmental field monitoring
• Quality control
• Industrial process control
• Detection systems for biological warefare agents
• Manufacturing of pharmaceuticals and replacement organs