This is a ppt about the working of biosensors. It also explains the different types of biosensors and it's applications in medical field.

1. BIOSENSORS

2. SENSOR AND A BIOSENSOR
• A sensor is a convertor that
measures a physical quantity and
converts it into a signal which can
be read by an observer or by a
instrument.
• A biosensor is an analytic device,
used for the detection of an
analyte, that combines a biological
component with a physicochemical
detector.

3. COMPONENTS OF BIOSENSOR

4. DESCRIPTION OF COMPONENTS
1.BIOLOGICAL ELEMENT:It’s
function is to interact with a target
compound i.e.,compound to be detected.
2.PHYSIOCHEMICAL
TRANSDUCER:It acts as an
interface,measuring the physical change
that occurs with the reaction at the
bioreceptor then transforming that
energy into measurable electrical output.
3.DETECTOR:Signals from the
transducer are passed to a
microprocessor where they are amplified
and analysed.The data is then converted
to concentration units and transferred to
a display or/and data storage device.

5. BASIC PRINCIPLE OF
BIOSENSOR
The desired biological material is
immobilized by conventional
methods(covalent or non-covalent
binding).This immobilized biological
material is in intimate contact with the
transducer. The analyte binds to the
biological element to form a bound analyte
which in turn produces the electronic
response that can be measured.

6. WORKING OF BIOSENSOR
a: Bio-element
b: Transducer
c: Amplifier
d. Processor
e: Display

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

8. TYPES OF BIOSENSORS
 Based on bio receptors:
• Enzyme biosensor
• Microbial biosensor
• Affinity biosensor
 Based on transducer:
• Potentiometric biosensor
• Amperometric biosensor
• Conductometric biosensor
• Optical biosensor
• Acoustic or piezoelectric biosensor

9. ELECTROCHEMICAL BIOSENSOR
• Electrochemical biosensors are normally based on enzymatic catalysis of a reaction that produces or
consumes electrons (such enzymes are rightly called redox enzymes). The sensor substrate usually contains
three electrodes: a reference electrode, a working electrode and a counter electrode. The target analyte is
involved in the reaction that takes place on the active electrode surface, and the reaction may cause either
electron transfer across the double layer (producing a current) or can contribute to the double layer potential
(producing a voltage). We can either measure the current (rate of flow of electrons is now proportional to
the analyte concentration) at a fixed potential or the potential can be measured at zero current (this gives a
logarithmic response).
• The potentiometric biosensor, (potential produced at zero current) gives a logarithmic response with a
high dynamic range. Such biosensors are often made by screen printing the electrode patterns on a plastic
substrate, coated with a conducting polymer and then some protein (enzyme or antibody) is attached. They
have only two electrodes and are extremely sensitive and robust. They enable the detection of analytes at
levels previously only achievable by HPLC and LC/MS and without rigorous sample preparation.

10. AMPEROMETRIC BIOSENSORS
Amperometric biosensors are self-
contained integrated devices based on
the measurement of the current
resulting from the oxidation or
reduction of an electro-active
biological element providing specific
quantitative analytical information.

11. PIEZOELECTRIC SENSORS
Piezoelectric sensors utilize crystals which undergo an elastic deformation
when an electrical potential is applied to them. An alternating potential (A.C.)
produces a standing wave in the crystal at a characteristic frequency. This
frequency is highly dependent on the elastic properties of the crystal, such that
if a crystal is coated with a biological recognition element the binding of a
(large) target analyte to a receptor will produce a change in the resonance
frequency, which gives a binding signal. In a mode that uses surface acoustic
waves (SAW), the sensitivity is greatly increased. This is a specialized
application of the Quartz crystal microbalance as a biosensor.

12. OPTICAL BIOSENSOR
• Optical biosensors have high specificity, sensitivity, small size
and cost-effectiveness. Multiple advanced concepts and highly
multidisciplinary approaches including microelectronics,
microelectromechanical systems (MEMSs), micro/nano-
technologies, molecular biology, biotechnology and chemistry
are applied in the implementation of new optical biosensors.
• They measure change in light absorption as reactants are
converted into products.
• Photon output for luminous or fluorescent process can be
detected with photomultiplier tubes or photodiode systems.

13. APPLICATIONS OF BIOSENSORS
 Food Analysis
 Study of biomolecules and their interaction
 Drug development
 Crime detection
 Medical diagnosis(both clinical and laboratory use)
 Environmental field monitoring
 Quality control
 Industrial Process Control
 Detection systems for biological warfare agents
 Manufacturing of pharmaceuticals and replacement
organs.
Biological Applications:
• DNA sensors : genetic monitoring,
disease diagnosis .
• Immunosensors: HIV, hepatitis.
• Cell based sensors: functional
sensors , drug testing.
• Point-of-care sensors: Urine ,
blood, steroids.

14. PREGNANCY TEST
hCG(human chorionic gonadotropin) is a
hormone secreted in pregnancy that is made by the
developing embryo soon after conception.
This hormone is detected using a biosensor
strip.The widely used strip uses manual reading
technique which employs lateral/ capillary flow
assay. The other method uses digital biosensor
technology which gives a positive result only in the
presence of hCG hormone in urine.The advantage
of this is that the chance of getting a wrong result
is less;as it’s more specific.The reason for its less
acceptance in the society is due to higher cost
compared to the former one.

15. CANCER DETECTION
• We know cancer is the first leading cause of death in the
world.There are nearly 200 distinct forms mainly lung,
prostrate, breast, ovarian, skin etc.
• The use of biosensors in cancer detection and monitoring
holds vast potential. Biosensors can be designed to detect
emerging cancer biomarkers and to determine drug
effectiveness at various target sites. Biosensor technology
has the potential to provide fast and accurate detection,
reliable imaging of cancer cells, and monitoring of
angiogenesis and cancer metastasis, and the ability to
determine the effectiveness of anticancer chemotherapy
agents.

16. CANCER
DETECTION
Biomarkers can be of various molecular origins, including DNA(ie., specific mutation, translocation, amplification, and loss of
heterozygosity), RNA, or protein(ie., hormone, antibody, oncogene, or tumor suppressor).
In terms of cancer, the analyte being detected by the biosensor is a tumor biomarker. Thus, by measuring levels of certain
proteins expressed and/or secreted by tumor cells, biosensors can detect whether a tumor is present, whether it is benign or
cancerous, and whether treatment has been effective in reducing or eliminating cancerous cells. Biosensors that can detect
multiple analytes may prove particularly useful in cancer diagnosis and monitoring, since most types of cancer involve multiple
biomarkers. The ability of a biosensor to test for multiple markers at once not only helps with diagnosis, but also saves time
and financial resources.
Piezoelectric and acoustic wave biosensors make up the class of mass-based biosensors. In terms of cancer detection,
piezoelectric biosensors are more commonly used. Piezoelectric sensors are based on changes in the mass of quartz crystals
when potential energy is applied to them. This change in mass generates a frequency, which can be converted into a signal.
Immunosensors and microcantilever sensors that use piezoelectric technology have proven useful in the identification of cancer
biomarkers.The unique feature of these sensors is that they identify change in mass in nanoscale,and hence used for early
detection which is mandatory in certain forms of cancer ;especially breast cancer.These sensors are user friendly and it provides
privacy for patients to detect certain cancers like breast,ovarian,prostrate,cervical etc. at early stages.

17. REFERENCES
• (http://www1.lsbu.ac.uk/water/enztech/biosensors.html)
• (https://sites.google.com/site/biossensoresfl/home/estrutura)
• (http://www.biologydiscussion.com/enzymes/biosensors/biosensors-features-
principle-and-types-with-diagram/10240)
• (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3292132/)
• (http://www.openpr.com/news/379984/Diabetes-Testing-is-the-Largest-
Biosensors-Market-in-Medical-Applications.html)
• (http://www.gatewaycoalition.org/files/hidden/sensr/ch1/1_3f.htm)

18. REFERENCES
• (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4934206/)
• Review Microbial biosensors Yu Lei a, Wilfred Chen, Ashok Mulchandani.
• (http://www.cbs.umn.edu/sites/cbs.umn.edu/files/public/downloads/microbial%2
0sensor%2006.pdf)
• Lecture FO7 – Affinity biosensors Dr. MAK Wing Cheung (Martin) (21 Feb 2014)
Biosensors & Bioelectronic Centre, IFM.
• (https://www.ifm.liu.se/edu/coursescms/tfya62/lectures/Affinity-
biosensors_TFYA62.pdf)

19. THANK YOU!!!
By,
ROHITH RAJ.S
RAKSHITH RAO.R