biosensor parushvarushiindustria019pt.pptx

Biosensors are nowadays ubiquitous in biomedical diagnosis as well as a wide range of other areas such as point-of-care monitoring of treatment and disease progression, environmental monitoring, food control, drug discovery, forensics and biomedical research. A wide range of techniques can be used for the development of biosensors. Their coupling with high-affinity biomolecules allows the sensitive and selective detection of a range of analytes. We give a general introduction to biosensors and biosensing technologies, including a brief historical overview, introducing key developments in the field and illustrating the breadth of biomolecular sensing strategies and the expansion of nanotechnological approaches that are now available.

Keywords: affinity reagents, biosensors, glBiosensors are nowadays ubiquitous in biomedical diagnosis as well as a wide range of other areas such as point-of-care monitoring of treatment and disease progression, environmental monitoring, food control, drug discovery, forensics and biomedical research. A wide range of techniques can be used for the development of biosensors. Their coupling with high-affinity biomolecules allows the sensitive and selective detection of a range of analytes. We give a general introduction to biosensors and biosensing technologies, including a brief historical overview, introducing key developments in the field and illustrating the breadth of biomolecular sensing strategies and the expansion of nanotechnological approaches that are now available.

Keywords: affinity reagents, biosensors, glBiosensors are nowadays ubiquitous in biomedical diagnosis as well as a wide range of other areas such as point-of-care monitoring of treatment and disease progression, environmental monitoring, food control, drug discovery, forensics and biomedical research. A wide range of techniques can be used for the development of biosensors. Their coupling with high-affinity biomolecules allows the sensitive and selective detection of a range of analytes. We give a general introduction to biosensors and biosensing technologies, including a brief historical overview, introducing key developments in the field and illustrating the breadth of biomolecular sensing strategies and the expansion of nanotechnological approaches that are now available.

Keywords: affinity reagents, biosensors, A biosensor is a device that measures biological or chemical reactions by generating signals proportional to the concentration of an analyte in the reaction. Biosensors are employed in applications such as disease monitoring, drug discovery, and detection of pollutants, disease-causing micro-organisms and markers that are indicators of a disease in bodily fluids (blood, urine, saliva, sweat). A typical biosensor is represented in Figure 1; it consists of the following components.

Analyte: A substance of interest that needs detection. For instance, glucose is an ‘analyte’ in a biosensor designed to detect g

1. Biosensors Dr.M.Surya Prabha VFSTRU

2. Introduction Sensor is a device which detects changes in a physical quantity like temperature, humidity, water flow, intensity of light etc. and converts it into a quantity that can be measured and/or analyzed . Similarly, a Biosensor is a device, which converts a Biological signal into a more useful electrical signal. A Biosensor is an analytical device that detects changes in Biological processes and converts them into an electrical signal. The term Biological process can be any biological element or material like enzymes, tissues, microorganisms, cells, acids, etc.

3. Principle of a Biosensor The desired biological material is usually in the form of an enzyme. By a process known as Electro enzymatic approach, which is a chemical process of converting the enzymes into corresponding electrical signals (usually current) with the help of a transducer. One of the commonly used Biological response is the oxidation of the enzyme . Oxidation acts as a catalyst and alters the pH of the biological material. The change in pH will directly affect the current carrying capacity of the enzyme, which is once again, in direct relation to the enzyme being measured

4. Working of Biosensors The combination of biological sensitive element and a transducer will convert the biological material into a corresponding electrical signal. Depending on the type of enzyme, the output of the transducer will be either current or voltage. If the output is voltage, then well and good. But if the output is current, then this current should be converted into equivalent voltage (using an Op-Amp based current to voltage converter) before proceeding further.

5. Usually, they consists of a test strip, which collect a small sample of blood to analyze the glucose levels. This particular sensor implements the Electroenzymatic approach i.e. oxidation of glucose. Diabetes is a disease characterized by the levels of glucose in the blood. Regularly checking the blood glucose levels is very important for diabetes patients. Glucometers are a type Biosensors, which measure the concentration of glucose in blood . The test strip consists of a trigger electrode and a reference electrode. When blood is placed on the test strip, a simple chemical reaction takes place and an electrical current is generated, which is directly proportional to the concentration of glucose. Internally, the Glucometer consists of a powerful processor like a Cortex-M3 or Cortex-M4 along with current to voltage converter, amplifier, filter and a display unit.

6. Different Types of Biosensors Biosensors are classified into two groups i.e. either based on the Biological Element used in the analysis or the method of transduction implemented. As mentioned already, some of the commonly used biological elements or bio-recognition elements are DNA, enzymes, antibodies, microorganisms, tissues, cell receptors etc. The next and most commonly used classification of Biosensors is based on the type of transduction used in the sensor i.e. type of physiochemical resulting from the sensing event.

7. Further, the biosensors based on method of transduction are again divided into three types. They are: Mass based Biosensors Optical based Biosensors Electrochemical Biosensors There are again few subclasses in each of these types. The following image shows a comprehensive list of different types of Biosensors.

8. Types Of Biosensors Biosensors like the finger-prick glucometers used to check blood sugar levels require the user to prick their finger and use the blood sample as the biological analyte. This is an example of an invasive biosensor. In contrast, the use of the pulse oximeter requires the user to simply insert their fingertip inside the instrument. This is an example of a non-invasive biosensor.   So, based on how the required biological analyte is applied, the biosensors may be categorized as invasive or non-invasive.

9. The biosensors can also be classified based on the type of biological recognition element and the transduction mechanism employed. The recognition element of a biosensor may be DNA, an antibody, enzyme, phage, tissues, cell receptors, microbial whole cells, etc.   Depending on the type of transducers used for the design of biosensors, they may be categorized into optical biosensors, electrochemical biosensors, or mass-based biosensors.   Optical fibers play a key role in the functioning of optical biosensors by sensing the biological analyte based on its property of fluorescence, absorption and scattering of light. They are non-electrical in nature and the measurements are based on the changes in the refractive index.  

10. Electrochemical biosensors are electrical in nature, where the sensing molecule or the recognition element will interact with the sample analyte. The electrical signal produced is often proportional to the concentration of the analyte.   Mass-based biosensors are electrical biosensors where the electrical signals produced are proportional to the mechanical or acoustic (sound) vibrations of the sensing molecules.   Commonly Used Biosensors The most commonly used biosensors are undoubtedly Glucose-biosensors or glucometers, which are blood or saliva-based, along with pregnancy strip tests, which are urine-based.   Glucometer The first commercially produced glucose biosensor was made by Yellow Springs Instrument in 1975. Since then, the design and performance of glucose biosensors have undergone drastic advancements.

11. Pregnancy Strip The other most commonly used biosensors are pregnancy test strips, which are antibody-based and determine the presence of HCG (human chorionic gonadotropin) from the blood or urine.   The recognition elements are the anti-HCG antibodies, which will agglutinate with the HCG of the blood/urine (if present) and form an agglutination line. The presence of a line indicates a positive test while the lack of the line is a negative test for pregnancy.

12. Characteristics Of Biosensors In biomedical diagnosis, the use of biosensors poses several advantages over routine laboratory techniques. as they are small, easy to use, cheap, and provide immediate results.   The performance of any biosensor is based on several key characteristics.   A biosensor should be selective in its ability to detect the presence of a specific analyte. The results generated by the biosensor should be reproducible, which means the biosensor should be able to generate identical readings for several identical samples.

13. The measurements should be accurate, with minimal variation between the values detected by the biosensor and the values obtained by conventional methods. The performance of the biosensor should be stable and should not be affected by external changes in temperature . It should be highly sensitive to detect even small amounts of the analyte and the measurements should be linear for a wide concentration range of the analyte.

14. Applications Since their development in the early 1950’s, Biosensors have become very important in the fields of medicine, clinical analysis and in general health monitoring. The advantages of biosensors over lab based equipment are as follows: Small size Low cost Quick results Very easy to use Apart from the desired medicine and health based applications, Biosensors have also found critical applications in several other fields like industrial processing, agriculture, food processing, pollution control etc.

15. So, the following is a small list of the potential fields where Biosensors are frequently used. Medicine, Clinical and Diagnostic Applications Environmental Monitoring Industrial Applications Food Industry Agriculture Industry

16. Medicine, Clinical and Diagnostic Applications The main area of interest of Biosensor is the Medicine, Clinical and Diagnostics applications. Electrochemical based Biosensors are commonly used in biochemical labs and clinics to monitor and measure glucose levels as well as lactic acid. Environmental Monitoring One of the major application of Biosensor is in the field of Environmental Pollution Monitoring. Especially, water pollution monitoring is an area where Biosensors have substantial advantage. Biosensors with sensing elements for nitrates and phosphates are becoming common for battling water pollutants. Another important application is for the military to detect chemicals and hazardous biological specimens that can be used a bio-weapons.

17. Industrial Applications Fermentation is a large industrial operation used in dairy, alcohol and other similar products.  Food Industry Commercial Biosensors that can measure carbohydrates, acids, alcohol, etc. are already available in the market. Biosensors are used in food industry for food quality control for measurement of amino acids, carbohydrates, alcohols, gases, etc. Some of the common food industries are Wine, Beer, Yogurt, soft drinks etc. Agriculture Industry Biosensors in the field of agriculture are generally used for detection of pesticides.