Biosensors: Components, principle, types and uses

What are biosensors?

Biosensors, short for “biological sensors”, are self-containing analytical devices which convert biological processes into electrical signals. Additionally, it measures the concentration of the analyte. They are omnipresent in the biomedical industry as well as many other areas. Ranging from disease monitoring to drug delivery, detection of pollutants to disease markers, it has undoubtedly revolutionized many fields.

Biological material that incorporates cells, tissues, microorganisms, enzymes, hormones, antibodies, natural products, etc that specifically interact with the analyte. Let’s gain more knowledge about it-

Components of biosensor:

Neurosensor

In other words, the biosensor integrates a biological system with a physicochemical transducer, producing an electronic signal which is proportional to a single analyte. The detector conveys it further.

The components can be classified into two broad categories:

1. Physical component (transducer and amplifier)

2. Biological component (bioreceptor and analyte).

Overview of components

  • Analyte– This is a substance that needs to be detected. For instance, molecules like protein, toxin, vitamin, sugar, metal ion, etc. 
  • Bioreceptor– In biosensors, the target is an analyte and the receptor is a substance on the surface that binds with the target and helps in detection. Moreover, any biomolecule which recognizes the target can potentially act as a bioreceptor. The most established bioreceptor molecule is an enzyme. Few other examples of bio-receptors are cells, DNA, aptamers, antibodies, nanoparticles, and proteins. The process of interaction of a bioreceptor with the  analyte results in a signal generation process in the form of heat, light, pH, mass change is known as bio-recognition.
  • Transducer – Transducers are any device that converts one form of energy to another form. The role of the transducer in biosensor is converting biorecognition elements into quantifiable signals. The energy conversion process is called signalization. Transducers convert biochemical events to electrical signals in these sensors. In addition, the transducers can utilize a piezoelectric mechanism or potentiometric mechanism based on the analyte and bioreceptor. 
  • Electronics– The part of the biosensor that processes the transduced signal and generates this signal for display. Moreover, it has complex circuitry that performs signal conditioning and converts analog signals to digital signals. The display unit of the biosensor then quantifies the processed signal from the electronics element.
  • Display– The display uses a user interpretation system so the user can understand easily. It consists of hardware and software that works together to give results of the biosensor in a user-friendly manner. Based on the needs of the end-user, the output display can be graphic, numeric, or an image.

Working principle of the biosensor:

Biosensors are basically based on the principle of the transduction of signals. The bioreceptor element interacts with a particular analyte. Afterward, the transducer converts the signals and generates an output. The intensity of the output is proportional to the concentration of the analyte taken under consideration. The electronic system amplifies and processes the signals for user interpretation.

Types of biosensors:

They are classified based on the biological elements used and transducers employed. 

Electrochemical biosensor:

This biosensor can detect biological elements like enzymes, cells, ligands, and tissues using electrochemical transducers. It is based on enzymatic catalysis that generates ions. Thus the concentration of the analyte is measured through this change.

These are furthermore classified into four kinds – amperometric, potentiometric, impedimetric, and voltammetric biosensors.

Thermal detection/ calorimetric biosensors:

In calorimetric biosensor, temperature detectors are integrated with the inactivated enzymes. Owing to thermometric biosensors we can estimate serum cholesterol. Moreover, the analyte concentration is evaluated to measure the heat reaction.

Resonant biosensors:

An acoustic wave transducer coupled with a bio-element (an antibody) is used for this sensor. Furthermore, the analyte concentration is measured with the help of alteration in resonant frequency. It utilizes crystals that undergo elastic deformation on applying electric potential. 

Piezoelectric biosensors:

A group of analytical devices that works on a principle of affinity interaction recording. It converts physical parameters, for instance, acceleration or pressure into electrical signals for measurement and is highly sensitive. The detection parts are united by the nanoparticles.

Optical detection biosensors:

Swayam Care Pulse oximeter

These biosensors use the principle of optical measurement. Optical detection biosensors use fiber optics as well as optoelectronic transducers. Did you know that pulse oximeters use optical biosensors that played a great role in this coronavirus pandemic?

We, at Swayam Care, offer pulse oximeters with the highest accuracy, made in India, in addition to this, it has a temperature indicator. You can use it for all ages from infants to old age.

Click here to view. 

Ion sensitive biosensors:

They can measure ion concentration in solution. Also called Enzyme Field-Effect Transistors and used for pH detection. These are semiconductor FETs that have ion-sensitive surfaces

Basic characteristics of biosensors:

.The key features of biosensors are as follows-

  1. The most important feature of biosensors is selectivity. The bioreceptor can detect a particular analyte.
  2. They show sensitivity or limit of detection, it is the minimum amount of analyte that it can detect.
  3. The biosensors reproducibility generates identical responses. The transducer and electronics characterizes it.
  4. It should give a quick response and should be biocompatible.

Applications of biosensors:

Biosensors have wide use in many fields, for instance, medical field, clinical research, monitoring, food industry, marine sector, etc.

  1. Blood-glucose biosensors: Used for diagnosis and evaluating patients with diabetes mellitus.
  2. Electrochemical-based biosensors: Used for measuring as well as monitoring lactic acid levels.
  3. Fluorescent biosensors: Used as imaging agents for drug and cancer discovery.
  4. It also aids in diagnosing infectious diseases like urinary tract infection(UTI) and also identify the end-stage in patients prone to heart failure.
  5. The various other applications include cardiac markers, immunosensor array, for military purposes, prosthetic devices, etc

REFERENCES-

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