What is biosensor


1 definition

Biosensors are sensors that contain biological components. According to the IUPAC definition, biosensors are devices with a stationary biological component (bioreceptor) that convert the specific biochemical reactions of an analyte with the bioreceptor into a mostly optical or electrical measurement signal and thus provide qualitative and quantitative evidence.

2 structure

A biosensor mainly consists of four parts. The first part is the bioreceptor, which is a membrane on which enzymes, organelles or antibodies are immobilized. This is followed by the transducer, the amplifier and the detector.

3 Principle of Operation

When binding to a certain analyte, the bioreceptor undergoes a change in its physicochemical properties (e.g. pH value, redox potential or temperature). The transducer recognizes these changes and converts them into an electrical signal that is amplified by an amplifier and thus made measurable. A detector now processes this signal and displays the corresponding measured value.

4 example

The glucose biosensor developed by Clark and Lyons in 1962 was the very first biosensor. Its functional principle is based on the conversion of glucose into gluconic acid and hydrogen peroxide with the participation of oxygen:

  • Glucose + O2 -> gluconic acid + H2O2

When gluconic acid is formed, two electrons are transferred to the glucose oxidase (GOD) bound cofactor FAD, which then becomes FADH2 is reduced. The FADH2 now reduces oxygen to hydrogen peroxide (H.2O2). Since hydrogen peroxide tends to break down into water and oxygen in the presence of metals, the measuring electrode is usually made of platinum. The electrons released by the decomposition of hydrogen peroxide cause a change in the current flow at the electrode. The difference is measured and is directly proportional to the glucose concentration in the blood sample.

see also:Blood glucose meter