Terminology » Biosensor Basics: Principles, Operation, and Applications

Biosensor Basics: Principles, Operation, and Applications

biosensor transducer analytical device medical device sensing

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:

Bio-receptor
Transducer
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.

Biosensor

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.