What is a Biosensor, Types of Biosensors and Applications

The first biosensor was invented in the year 1950 by American biochemist “L.L Clark”. This biosensor is used to gauge oxygen in the blood, and the electrode used in this sensor is named as Clark electrode or oxygen electrode. Afterward, a gel with glucose oxidize enzyme was layered on the oxygen-electrode to compute blood sugar. Correspondingly, enzyme urease was utilized with an electrode that was invented particularly for NH4++ions for calculating urea in fluids of the body such as urine and blood.

There are three generations of biosensors available in the market. In the First type of biosensor, the reaction of the product disperses to the sensor and causes the electrical reaction. In the second type, the sensor involves in particular mediators between the sensor and the response in order to produce a better response. In the third type, the response itself causes the reaction and no mediator is straightly involved. This article gives an overview of a biosensor, working of biosensors, different types, and its applications.

What is a Biosensor? 

Biosensors can be defined as analytical devices which include a combination of biological detecting elements like sensor system and a transducer. When we compare with any other presently existing diagnostic device, these sensors are advanced in the conditions of selectivity as well as sensitivity. The applications of these Biosensors mainly include checking ecological pollution control, in agriculture field as well as food industries. The main features of biosensors are stability, cost, sensitivity, and reproducibility.

Bio Sensor
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Main Components of a Biosensor

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

Main Components of a Biosensor
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Working Principle of Biosensors 

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.

Working of Biosensors 

The electrical signal of the transducer is frequently low and overlay upon a fairly high baseline. Generally, the signal processing includes deducting a position baseline signal, obtained from a related transducer without any biocatalyst covering.


The comparatively slow character of the biosensor reaction significantly eases the electrical noise filtration issue. In this stage, the direct output will be an analog signal however it is altered into digital form and accepted to a microprocessor phase where the information is progressed, influenced to preferred units and o/p to a data store.

Types of Biosensors 

The different types of biosensors are classified based on the sensor device as well as the biological material that is discussed below.

1. Electrochemical Biosensor 

Generally, the electrochemical biosensor is based on the reaction of enzymatic catalysis that consumes or generates electrons. Such types of enzymes are named as Redox Enzymes. The substrate of this biosensor generally includes three electrodes such as a counter, reference, and working type.

Electrochemical Biosensor
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The object analyte is engaged in the response that happens on the surface of an active electrode, and this reaction may source also electron-transfer across the dual layer potential. The current can be calculated at a set potential.

Electrochemical biosensors are classified into four types

  • Amperometric Biosensors
  • Potentiometric Biosensors
  • Impedimetric Biosensors
  • Voltammetric Biosensors

2. Amperometric Biosensor

An amperometric biosensor is a self-contained incorporated device based on the amount of the current ensuing from the oxidation offering exact quantitative analytical information.

Generally, these Biosensors have reaction times, energetic ranges & sensitivities comparable to the Potentiometric-biosensors. The simple amperometric biosensor in frequent usage includes the “Clark oxygen” electrode.

Amperometric Biosensor
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The rule of this biosensor is based on the amount of the flow of current between Counter Electrode and the working which is encouraged by a redox response at the operational electrode. Choosing analyte centers is essential for a wide selection of uses, comprising high-throughput medicine screening, quality control, problem finding and handling, and biological checking.

3. Potentiometric Biosensors 

This type of biosensor provides a logarithmic reply by means of a high energetic range. These biosensors are frequently complete by monitor producing the electrode prototypes lying on a synthetic substrate, covered by a performing polymer with some enzyme is connected.

Potentiometric Biosensors
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They comprise two electrodes which are enormously responsive and strong. They allow the recognition of analytes on stages before only attainable by HPLC, LC/MS & without exact model preparation.

All types of biosensors generally occupy least sample preparation because the biological detecting component is extremely choosy used for the analyte troubled. By the changes of physical and electrochemical the signal will be generated by in the layer of conducting polymer due to modifying happening at the outside of the biosensor.

These changes might be credited to ionic force, hydration, pH, and redox responses, the later as the label of enzyme rotating above a substrate. In FETs, the gate terminal has been changed with an antibody or enzyme, can also sense very-low attentions of different analytes because the required of analyte toward the gate terminal make a modify in the drain to source current.

4. Impedimetric Biosensors 

The EIS (Electrochemical impedance spectroscopy) is a responsive indicator for a broad range of physical as well as chemical properties. A rising trend towards the expansion of Impedimetric-biosensors is being presently observed. The techniques of Impedimetric have been executed to differentiate the invention of the biosensors as well as to examine the catalyzed responses of enzymes lectins, nucleic acids, receptors, whole cells, and antibodies.

Impedimetric Biosensors
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5. Voltammetric Biosensor 

This communication is the base of a new voltammetric biosensor to notice acrylamide. This biosensor was built with a carbon glue electrode customized with Hb (hemoglobin), which includes four prostatic groups of the hem (Fe). This type of electrode shows a reversible oxidation or reduction procedure of Hb (Fe).

Physical Biosensor 

In conditions of classification, physical biosensors are the most fundamental as well as broadly used sensors. The main ideas behind this categorization also happen from inspecting the human minds. As the general working method behind the intelligence of hearing, sight, touch is to react on the exterior physical stimuli, therefore any detecting device that offers reaction to the physical possessions of the medium was named as a physical biosensor.

The physical biosensors are classified into two types namely piezoelectric biosensor and thermometric biosensor.

Piezoelectric Biosensors 

These sensors are a collection of analytical devices which works on a law of “affinity interaction recording”. The platform of a piezoelectric is a sensor element works on the law of oscillations transform due to a collection jump on the surface of a piezoelectric crystal. In this analysis, biosensors having their modified surface with an antigen or antibody, a molecularly stamped polymer, and heritable information. The declared detection parts are normally united by using nanoparticles.

Piezoelectric Biosensors
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Thermometric Biosensor 

There are various types of biological reactions which are connected with the invention of heat, and this makes the base of thermometric biosensors. These sensors are usually named as thermal biosensors

Thermometric Biosensor
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Thermometric-biosensor is used to measure or estimate the serum cholesterol. As cholesterol obtains oxidized through the enzyme cholesterol oxidize, then the heat will be produced which can be calculated. Similarly, assessments of glucose, urea, uric acid, and penicillin G can be done with these biosensors.

Optical Biosensor 

The Optical biosensor is a device that uses an optical measurement principle. They use the fiber optics as well as optoelectronic transducers. The term optrode represents a compression of the two terms optical & electrode. These sensors mainly involve antibodies and enzymes like the transducing elements.

Optical Biosensor
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Optical biosensors permit a secure non-electrical inaccessible sensing of equipment. An extra benefit is that these frequently do not need reference sensors, because the comparative signal can be produced by using the similar light source like the sampling sensor. The optical biosensors are classified into two type’s namely direct optical detection biosensor and labeled optical detection biosensor.

Wearable Biosensors 

The wearable biosensor is a digital device, used to wear on the human body in different wearable systems like smart watches, smart shirts, tattoos which allows the levels of blood glucose, BP, the rate of heartbeat, etc

Wearable Biosensors
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Nowadays, we can notice that these sensors are carrying out a signal of improvement to the world. Their better use and ease can give an original level of experience into a patient’s real-time fitness status. This data accessibility will let superior clinical choice and will effect in enhanced health results and extra capable use of health systems.

For the human beings, these sensors may assist in premature recognition of health actions and prevention of hospitalization. The possibility of these sensors to reduce hospital stays and readmissions will definitely attract positive awareness in the upcoming future. As well, investigate information says that WBS will definitely carry a cost-effective wearable health equipment to the world.

Biosensors Applications 

In recent years, these sensors have become very popular, and they are applicable in different fields which are mentioned below.

Applications of Biosensor
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  • Common healthcare checking
  • Metabolites Measurement
  • Screening for sickness
  • Insulin treatment
  • Clinical psychotherapy & diagnosis of disease
  • In Military
  • Agricultural, and Veterinary applications
  • Drug improvement, offense detection
  • Processing & monitoring in Industrial
  • Ecological pollution control

From the above article, finally, we can conclude that biosensors and bioelectronics have been used in a lot of areas of healthcare, life science research, environmental, food & military applications. Further, these sensors can be enhanced as nanobiotechnology. The best example of the future use of nanobiotechnology includes electronic paper, contact lens, and Nokia morph. Here is a question for you, what are wearable biosensors?

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