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.

1. BIOSENSOR
T A S M I N A F E R D O U S S U S M I
J A S H O R E U N I V E R S I T Y O F S C I E N C E A N D T E C H N O L O G Y

2. BIOSENSOR
• The term “biosensor” is short for “biological sensor”
• A device made up of a transducer and a biological
element that may be an enzyme, an antibody, or a nucleic
acid.
• Has a biological component that acts as the sensor and an
electronic component
• Detects and transmits the signal.
• The first biosensor was invented in the year 1950 by
American biochemist “L. C. Clark”.

3. MAIN COMPONENTS OF A BIOSENSOR
Biosensor
Elements
Biological Elements
Enzymes
Cells
Antibody
Physical Elements
Transducer
Amplifier
Electric Potencial

4. MAIN COMPONENTS OF A BIOSENSOR
• Analyte: A substance of interest that needs detection.
• Bioreceptor: A molecule that specifically recognizes the analyte is known as a
bioreceptor.
• Transducer: The transducer is an element that converts one form of energy into
another.
• Electronics: This is the part of a biosensor that processes the transduced signal
and prepares it for display.
• Display: The display consists of a user interpretation system such as the liquid
crystal display that generates numbers or curves understandable by the user.

5. MAIN COMPONENTS OF A BIOSENSOR

6. WORKING PRINCIPLE OF BIOSENSOR
• Analyte diffuses from the solution to the surface of the Biosensor.
• Analyte reacts specifically & 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 change in the optical/electronic properties is measured or converted into

7. WORKING PRINCIPLE OF BIOSENSOR
Biological
Material
Bound Analyte
Biological
Response
Electronic
Response
Measurement
Analyte

8. CHARACTERISTICS OF A BIOSENSOR
• Selectivity perhaps the most important feature of a biosensor. Selectivity is the ability
of a bioreceptor to detect a specific analyte in a sample containing other admixtures
and contaminants.
• Reproducibility is the ability of the biosensor to generate identical responses for a
duplicated experimental set-up.
• Stability is the degree of susceptibility to ambient disturbances in and around the
biosensing system.
• Sensitivity The minimum amount of analyte that can be detected by a biosensor
defines its limit of detection (LOD) or sensitivity.

9. PROPERTIES OF A GOOD BIOSENSOR
• Highly specific for the analyte.
• The response should be linear.
• The device should be small & biocompatible.
• It should be low cost, small & easy to use.
• Assay cost should be lower than conventional tests.
• The assay should be fast, reliable & repeatable.

10. TYPES OF BIOSENSORS
• Electrochemical Biosensor
o Amperometric Biosensors
-Principle- Movement of electrons
o Potentiometric Biosensors
-Principle- Detects ionic Conc.
o Impedimetric Biosensors
-Principle- Electrochemical Impedence
spectrometry
o Voltammetric Biosensors
-Principle-Carbon glue electrodes with HB
• Physical Biosensor
o Piezoelectric Biosensors
-Principle- Detect sound, vibration, frequencies
o Thermometric Biosensor
-Principle- Detects Heat by thermistor

11. TYPES OF BIOSENSORS
• Optical Biosensor
• Wearable Biosensors
• Enzyme Biosensor
• DNA Biosensor
• Immunosensors
• Magnetic Biosensors
• Resonant Biosensors
• Thermal Detection Biosensor

13. GLUCOSE SENSORS
• The first enzyme-based electrode
for glucose detection was reported by L. L
Clark in 1962
• are designed to detect glucose levels
• is vital to managing diabetes
• selective, sensitive, and relatively easy to
use

14. • Reduces risk of developing complications with diabetes.
• Allows diabetics to see if the insulin and other medications they are taking
are working.
• Gives diabetics an idea as to how exercise and food affect their blood sugar.
• May prevent hypoglycemia or hyperglycemia.
WHY MONITOR BLOOD GLUCOSE?

15. COMMON ENZYMES IN GLUCOSE SENSORS
Common enzymes (bioreceptors) that are used to detect glucose include:
• Glucose oxidase (GOx)
• Glucose dehydrogenase (GDH)
Enzyme with Co-factor
• Glucose dehydrogenase nicotinamide adenine dinucleotide (GDH-NAD)
• Glucose dehydrogenase flavin adenine dinucleotide (GDH-FAD)
• Glucose dehydrogenase pyrroloquinoline quinone (GDH-PQQ)

16. WORKING PRINCIPLE
• Analyte: glucose is the analyte that the biosensor is designed to detect.
• Bioreceptor: For the detection of glucose, specific enzymes are used, which are
proteins that facilitate a chemical reaction.
• Transducer: Most modern-day glucose meters and continuous glucose monitors
measure electrical signals, although earlier generations of glucose meters used a
colorimetric process (color change) that was measured optically.
• Electronics and display: These components process the transduced signal and
prepare it for display.

17. MECHANISM OF GLUCOSE SENSORS

18. EVOLUTION OR GENERATION OF GLUCOSE
SENSORS
Generation Description Advantages/Drawbacks
First generation It works on oxygen reduction to hydrogen peroxide. Drawback: possible interference of
compounds (e.g. ascorbic acid)
presented in the blood. Original wire
electrodes were expensive.
Second
generation
It uses electron mediators instead that replace oxygen
in the reaction. Advanced types of embranes are also
used.
Advantage: the assay is less sensitive to
interferents like ascorbic acid
Third generation It is based on the direct electron transfer between
enzyme and membrane/electrode – electron
can be replaced by conductive membrane; other
of enzymes can be used.
It exerts similar analytical properties like
the 2nd generation, the absence of
electron mediator makes the
process simpler and avoiding
problematic materials.
Fourth Enzyme in the biosensor is replaced by an artificial
structure exerting similar catalytical properties
including specificity like the original enzyme.
Advantage: easier mass production,
better uniformity and reproducibility.
the other hand, specificity should be
verified.

19. EVOLUTION OR GENERATION OF GLUCOSE
SENSORS

20. THE DIFFERENT TYPES OF GLUCOSE SENSORS
JBkj
• Discrete form (blood glucose meter test
strips) or
cbkjb
• Wearable form (a continuous glucose
monitor).

21. APPLICATIONS OF BIOSENSORS