Types of Biosensors | Working principle of Biosensors types

This article covers Biosensor types and working principle of biosensors. It describes different types of Biosensors and working of biosensors viz. optical biosensors, electrochemical biosensors and Piezoelectric biosensors.

Definition:The analytical device which is used for detection of analyte and combines it with physico-chemical detector or transducer is known as Biosensor. The figure-1 depicts working of such biosensor.

Following are the Biosensor types.
• Piezoelectric sensor
• Electrochemical sensor
• Optical sensor

Biosensor Working Principle

A biosensor consists of following components on a single chip.
1. Bio-receptor
2. Transducer element
3. Electronics circuit and display

Following points summarize typical steps involved in working of biosensors.
• It detects the input physical change due to biological element.
• The transducer element transforms the physical change into appropriate electrical signal.
• The electrical signal is amplified, processed and given to display in user desired format.

The biological material is im-mobilized by conventional methods. This immobilized biological material is in contact with the transducer. The analyte binds to biological material to form bound analyte. This consecutively produces electronic response which can be measured.

All the biosensors are characterized by few parameters. These parameters are sensitivity, selectivity, range, response time, reproducibility, detection limit, life time and stability. These parameters are considered in selection of biosensors as per requirements and applications. FOllowing steps are involved in the development of different types of biosensors.
➨Selection of appropriate bioreceptor and recognition molecule.
➨Selection of appropriate immobilization method
➨Selection and design of transducer
➨Design of biosensor as per parameters mentioned above
➨Packaging of all the components in a single device

Different types of Biosensors | Working of biosensors

Biosensors can be categorized as per biological element or transducing element used. Biological elements typically used are enzymes, micro-organisms, antibodies, biological tissue, organelles etc. The method of transduction depends on type of physicochemical change as a result of sensing event. Primarily biosensors based on transducer element are mass based, electrochemical biosensors and optical biosensors.

• Mass based Biosensors include Magnetoelectric, Piezoelectric (QCM-Quartz crystal microbalance, SAW ) etc.
• Electrochemical Biosensors include potentiometric sensors, Amperometric sensors, Impedimetric sensors, conductometric sensors etc.
• Optical Biosensors include SPR (Surface Plasmon Resonance), Raman & FTIR, Fiber optics etc.

Following section describes different types of biosensors and working of biosensors.

Piezoelectric biosensors

This mass based biosensors work based on acoustics principle i.e. sound vibrations. These sensors produce electrical signal based on applied mechanical force. In this mode, sensor modules are attached to piezo-electric surface which provide interactions between analyte and sensing molecules which set up mechanical vibrations. Here piezoelectric sensor functions as mass to frequency transducer which translates electrical signal in proportion to the amount of the analyte.

Piezoelectric biosensors are used to detect and quantify various biomarkers in clinical samples such as proteins, hormones, nucleic acids and infectious agents. They are also used in drug discovery and screening, environmental monitoring and food quality control.

Electrochemical Biosensors

In this Biosensor type, membrane holds sensing molecules and excludes interfering species from analyte solution. The sensing molecules react with compounds to be detected which sparks electrical signal in proportion to concentration of analyte. Based on this working principle, the electrochemical biosensor employs potentiometric, amperometric and impedimetric transducers. They convert chemical information into measurable amperometric signal.

Electrochemical Biosensor such as amperometric glucose sensors are used to monitor blood glucose levels in individuals for diabetes management. They are used in environmental analysis, biomedical research amd point-of-care testing.

Optical Biosensors

In this biosensor type, optical fiber allows detection of analytes on basis of absorption, fluorescence or light scattering. Optical biosensors allow multiple analytes to be detected by using different monitoring wavelengths. Various parameters such as changes in wavelength, time, wave propagation, intensity, distribution of spectrum or polarity of the light are used in optical biosensors for measurement purpose.

Optical biosensors are widely used in medical diagnostics for detection of various infectious diseases, cancer biomarkers and genetic disorders. They are used to monitor environmental pollutants such as heavy metals, pesticides, toxins etc. They are used for rapid detection of foodborne pathogens, allergens and contaminants in food products. They also find applications in monitoring and optimization of bioprocesses.

The other types of biosensors are magnetic biosensors, thermal biosensors, conductive biosensors, acoustic biosensors and so on.

Biosensor Manufacturers

Following table mentions popular manufacturers of Biosensors and equipment developers which can be used for biosensor development and other activities.

Refer list of Biosensor manufacturers >> for biosensor companies which manufactures biosensors for different applications.

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