Biosensor Basics: Principles, Operation, and Applications

This page covers the fundamentals of biosensors, including their applications, advantages, and the mechanism behind their operation. A biosensor is essentially an analytical device used for the detection of an analyte, combining a biological component with a physico-chemical detector.

It integrates three main functionalities:

1. Bio-receptor
2. Transducer
3. Electronics circuit and display

According to Professor Leland C. Clark, often regarded as the “father of biosensors,” a biosensor is a device that incorporates a biological sensing element either intimately connected to or integrated within a transducer.

Figure: Schematic diagram explaining how a biosensor works.

It can also be described as an analytical device that converts a biological response into an electrical signal, detecting, recording, and transmitting information related to a physiological process or change.

How Does a Biosensor Work?

Let’s break down the operational steps:

• Step 1: Detects the input based on physical change resulting from a reaction.
• Step 2: Converts the input into an electrical signal.
• Step 3: Amplifies the electrical signal and processes it using a processor.
• Step 4: Displays the processed signal.

As mentioned above, step-1 can be one of the following reaction leading to physical change.

The physical change in Step 1 can arise from various reactions, including:

• Heat output (calorimetric biosensors)
• Light output (optical biosensors)
• Changes in charge distribution, leading to electrical potential (potentiometric biosensors)
• Electron movement during redox reactions (amperometric biosensors)
• Effects due to the mass of reactants (piezoelectric biosensors)

Generations of Biosensors

Biosensors can be categorized into three generations:

• First Generation: These devices rely on the diffusion of the normal reaction product to the transducer, which then generates an electrical response.
• Second Generation: These biosensors utilize specific mediators between the reaction and the transducer to produce an improved response.
• Third Generation: In this type, the reaction itself causes the response directly, without involving product or mediator diffusion.

Advantages of Biosensors

Biosensors offer several benefits:

• Rapid and continuous measurements
• Fast response time
• Minimal reagent usage for calibration
• Ability to measure non-polar molecules, which are difficult to assess using conventional devices.

Applications of Biosensors

Biosensors have a wide range of applications, including:

• Food analysis
• Wastewater treatment
• Environmental monitoring
• Monitoring glucose levels in diabetic patients
• Protein engineering and drug discovery
• Wireless Body Area Network(WBAN)