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Electronic Biosensors

Biosensors are nowadays used in biomedical diagnosis as well as in 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. One type of such sensor is electronic biosensor which uses “Bioreceptor, Transducer and Display” to electronically transmit signals.

This is the part of a biosensor that processes the transduced signal and prepares it for display. It consists of complex electronic circuitry that performs signal conditioning such as amplification and conversion of signals from analogue into the digital form. The processed signals are then quantified by the display unit of the biosensor.


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Types of Electronic biosensors


  1. Potentiometric: Potentiometric sensor is a type of chemical sensor that may be used to determine the analytical concentration of some components of the analyte gas or solution. These sensors measure the electrical potential of an electrode when no current is present.

potentiometric sensor


  1. Amperometric: The principle of amperometric sensor is based on measuring current generated by enzymatic or bio affinity reaction at the electrode surface, at a constant working potential with respect to the reference electrode.

  1. Cantilever-based sensor: Cantileverbasedsensors are extremely versatile, they can be operated in air, vacuum and liquid environment, they can transduce a number of different signals, such as magnetic, stress, electric, thermal, chemical, mass, and flow, into a mechanical deflection detected with sub-Angstrom resolution.



  Important Characteristics of Electronic Sensors:

  1. Selectivity: Selectivity is 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. The best example of selectivity is depicted by the interaction of an antigen with the antibody. Classically, antibodies act as bioreceptors and are immobilised on the surface of the transducer. A solution (usually a buffer containing salts) containing the antigen is then exposed to the transducer where antibodies interact only with the antigens. To construct a biosensor, selectivity is the main consideration when choosing bioreceptors. 


  1. Sensitivity: The minimum amount of analyte that can be detected by a biosensor defines its limit of detection (LOD) or sensitivity. In a number of medical and environmental monitoring applications, a biosensor is required to detect analyte concentration of as low as ng/ml or even fg/ml to confirm the presence of traces of analytes in a sample. For instance, a prostate-specific antigen (PSA) concentration of 4 ng/ml in blood is associated with prostate cancer for which doctors suggest biopsy tests. Hence, sensitivity is considered to be an important property of a biosensor. 


  1. Reproducibility: Reproducibility is the ability of the biosensor to generate identical responses for a duplicated experimental set-up. The reproducibility is characterised by the precision and accuracy of the transducer and electronics in a biosensor. Precision is the ability of the sensor to provide alike results every time a sample is measured and accuracy indicates the sensor’s capacity to provide a mean value close to the true value when a sample is measured more than once. Reproducible signals provide high reliability and robustness to the inference made on the response of a biosensor.


Challenges Faced in Field of Electronic Biosensors

 Although biosensors employ fundamental sciences, it can hardly be rationalised as ‘curiosity-driven’ research. On the other hand, research in industry obeys the trend of ‘follow the money’ to some extent. Given the success of commercial glucose sensors, biosensor research is, of course, very lucrative for the industry’s long-term sustainability. However, it takes quite a long time to produce a commercially viable device from a proof of concept demonstrated in academia. This also involves a number of risks that industries are reluctant to face.

As a result, there are unaddressed mandatory issues concerning the production of a commercial biosensor, such as:

  • Identification of the market that is interested in a biosensor for a specific analyte of interest.
  • Clear-cut advantages over existing methods for analyses of that analyte.
  • Testing the performance of the biosensor both in use and after storage. Response of a biosensor after 6 months of storage is the absolute minimum for any practical commercial application.
  • Stability, costs and ease of manufacturing each component of the biosensor.
  • Hazards and ethics associated with the use of the developed biosensor.

Although, there have been challenges in implementing biosensors but the nature of biosensors is ubiquitous which outweighs its disadvantages to a great extent.



The rapid development in the field of biosensors over the past decades, both at the research and product development level, is mainly due to: (i) developments in miniaturisation and microfabrication technologies; (ii) the use of novel bio-recognition molecules; (iii) novel nanomaterials and nanostructured devices; and (iv) better interaction between life scientists and engineering/physical scientists.

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Magnetic Materials And Background

The history of the usefulness of magnetic substances is very long and extends to the period of Ved-Vedanta.

But now the usefulness and importance of magnetic materials has increased exponentially, especially with the development of new devices. In the last 20 years, I have never witnessed such an increase in the use of magnetic substances in the industry. These include computers, medical instruments, etc. as magnetic sensors (known as GMR sensors, which have the effect of electromagnetic force of matter, a sensor that has a very small effect even with a small magnetic field) have been used since before the 1990s. But in 1997, IBM first used the GMR sensor as a “read head” on a computer. Later, it brought a revolution on the internet.I don’t want to go there now. The subject I have been researching now is the “GMR sensor” and the “nano-particles” (a meter-long object, a fraction of a million times the size of a micrometer, called a nanometer) and the combination of the two (i.e., the GMR sensor and the nano-particles). Using these sensors, many chronic diseases, such as the early stages of cancer (as soon as the disease is diagnosed), can be detected and prevented and treated immediately.

Despite the significant achievement in the field, there are some barriers to using GMR sensors and nano-ears. For practical use in hospitals, for example, the sensitivity of the sensor and the magnetic moment of the nanoparticles must be by 10 / Oe (Orested) and more than 300 EMU/g, respectively. And there is a lot of research going on right now for the development of new technology and my main priority is related to research on how to detect the disease as soon as it is diagnosed (called Early Disease Detection Technology) and prevent the disease from spreading by treating it immediately. .You will find another utility of magnetic nano-ear in the field of magnetic imaging. Extensive research is underway, too. The use of magnetic nanoparticles is not limited to this. Cancer cells can be killed using magnetic nanoparticles using alternating magnetic fields. Similarly, the use of magnetic nanoparticles can be further expanded to be used as medicine. Can also be expanded to produce energy and space research. As far as I know, strong, friendly, and long-term collaboration between engineers, physicists, chemists, biologists, etc. is needed to develop potential new technologies. Interested dignitaries can study through the link below. For now, I want permission to end this brief description. Also, in the near future, I will be more interested in the use of magnetic materials. Thank you.


I informed the usefulness of magnetic matter in the biomagnetic field in my January 8, 2016 report. Shortly afterward, I also give a brief overview of the history of magnetic matter in a report published on January 21, 2016. We know that to understand anything basic, one has to go to the root of the thing. In the same way, in order to understand the usefulness of magnetic substances, one should not go to the root of Tesco. In today’s report too, I have decided to continue the history of magnetic matter.

Just as a driver can reach the destination quickly or not, that is, he can get into an accident in the middle, but if you drive slowly, follow the traffic rules, follow the traffic rules and drive slowly, you will reach the destination. Like a sweet Nepali proverb, However, I will continue to introduce you to the history of magnetic materials, in simple Nepali language, through MyWorld’s Science Blog, in a way that everyone can understand, starting with the history of magnetic materials, how they are being used in the medical field and how they will continue to grow in the future.

As simple as it sounds to hear the magnetic matter, it is just as difficult to understand and recognize, but it is not impossible! In the January 21 report, we discussed the contribution from Gilbert, Bernoulli, (Franklin, Orested, Ampere,) and Michael Faraday in particular, who proved that there is a correlation between the electric charge and the magnet, and later in 1945, it was shown again that there is a correlation between the magnet and the ray of light. Well-known physicist and mathematician James Clark Maxwell was encouraged at the time, but so was his concern, that the discovery by a bookstore (in his eyes, Michael Faraday) how could he (Michael Faraday) invent such a miracle? Inspired by new discoveries one after another by Michael Faraday, Maxwell came up with four famous mathematical formulas, known polularly by his name. These four equations theoretically explain the experimentals results of Michael Faraday. Surprisingly, these four sutras are looked very simple in nature, but they are very difficult to understand, like Sanskrit verses, which are easy to read but very difficult to explain! In this report, I will try to explain the four questions: DIV.E = r (i) DIV. B = 0 (ii) Curl × E = -dB/dt (iii) (1/µ0) Curl × B = j + x dE/dt (iv) (1) in a simple terms.

Here, formula one (i) represents the electrical law of Gauss. This means that the electricity emitted from any volume is directly related to the charge within the volume. The second formula represents Gauss’s magnetic law, which means that the single-pole north or the single-pole south of a magnet is never alone, just as the electric is positively and negatively charged. That is, the magnetic flux that enters or tries to enter the closed field is zero. Formula three, known as Faraday-Maxwell’s formula, is directly related to the rate at which the voltage accumulated within any closed field changes the magnetic flux. (This formula is also known as Faraday’s law of induction) and the formula is also known as the circuit law of four amperes, which means that within a closed circle, the change of electric current and the time of the electric field coincide directly within the magnetic field. Relates to the penetrating area. Even if you explain it in simple language, it may still be difficult to understand the meaning of these four sutras. So I want to briefly express S’s shar. In short, just as the formulas of an electric field are related to the electric charge and electric field located around a point, so the formulas of a magnetic field are related to the magnetic field located near a point and the current density located around that point. The most important of these four Maxwell formulas is that they can detect any electromagnetic radiation, such as a ray of sun, in which both electric and magnetic rays travel together at the speed of light, and the speed of light, in a vacuum, is its wavelength. ) And comes to be a qualitative value of frequency. It is important to understand that this formula applies not only to light but also to all kinds of electromagnetic waves in the universe.

Fig. 1: electric and magnetic pair., Traveling (speed @ 3 × 108 m / sec). E and H are 90 degrees apart.

As seen in Maxwell’s four formulas above, the magnetic and electric constants, just called permeability and permeability, respectively, are multiplied by the square root, inverted, and the speed of the sun’s rays in a vacuum is exactly 30 million per meter, ie , c =. Surprisingly, the Sun’s motion corresponds exactly to the ratio of the average electric field (Eavg) and magnetic field (BAvg) mentioned in Maxwell’s formula (i.e. 30 million meters per second). There is no doubt that the basis of electricity and magnetic matter is electric charges and magnetic dipoles (magnetic dipoles and loops of electric current are the same). In the magnetic field, Maxwell’s Sutra, as well as Lorenz’s Sutra, is another important discovery. Lorenz’s law states that any moving particle with charge, q, and speed, v, the electric and magnetic force it experiences, is given by the following formula (2).f=q(E+ v×B) (2) There is no doubt that the basis of electricity and the magnetic matter is electric charges and magnetic dipoles (magnetic dipoles and loops of electric current are the same). In the magnetic field, Maxwell’s Sutra, as well as Lorenz’s Sutra, is another Mahota full-fledged. Lorenz’s law states that any moving particle with charge, q, and speed, v, the electric and magnetic force it experiences, is given by the following formula (2). Magnetic materials are now widely used, especially in telecom, computers, and other consumer goods. Widely used electromagnets are being replaced by smaller permanent magnets.

As I mentioned in a report published on January 8, these magnets have been widely used in the field of computers and have now resulted in the revolution of the Internet. Other areas where they shine include Earth Science, Space Technology, Food Science, Environmental Monitoring, etc. Also, the use of magnetic materials in the medical field has increased dramatically. In the coming days, I will report other important materials of significant interest in the industrial sectors such as medical diagnostics, DNA sequencing, point of care testing, cancer detection, prevention, and treatment. Please keep checking back the blog page for important updates.