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A biosensor is a sensor exploiting a biomolecule and is used to measure the presence of a certain substance in a liquid. For example, the medical world uses biosensors to detect a virus in the blood or to measure glucose levels in blood. These are mainly point-of-care applications, where direct results are important.
A biosensor consists of a specific biological recognition element and an element that transforms the change of the recognition into a measurable electrical signal (the transducer, see Figure 1).
The recognition element can be a protein, an antibody, a DNA-string or an enzyme. These natural molecules specifically react or bind to one particular other substance.
For example, an antibody adheres to a virus or a DNA-string adheres to the complementary strand to form a helix. This process changes the biosensor permanently, most biosensors can therefore only be used once.
The transducer converts the change into a measurable electrical signal. An electrochemical biosensor usually uses the working electrode as a transducer.
Blood sugar test
A well-known example of using a biosensor is the blood sugar test. The biosensor contains glucose oxidase. This enzyme “eats” glucose and produces hydrogen peroxide as a by-product. This peroxide reacts at the electrode which generates a measurable electric current. If you know how much hydrogen peroxide was created, you know how much sugar (glucose) was consumed and so how much sugar is present in the blood.
Biosensors are typically used in point-of-care applications. These are situations where a certain test has to be performed on-site and there is no possibility to have the test performed in a laboratory.
An example of this is an ambulance worker who, in the event of an accident, has to determine whether the injured person is infected with HIV or not. This test can be performed with a portable potentiostat, such as the Sensit Smart or EmStat combined with the right biosensor.
The blood sugar test is also an example. Patients suffering from diabetes can carry out this test at home without having to go to the hospital laboratory.
Some biosensors contain substances that can capture multiple substances in one experiment. These biosensors can be used by potentiostats with an integrated multiplexer, such as the EmStat MUX. This potentiostat can measure several different electrochemical reactions simultaneously.
Biosensors available on Palmsens.com
On the website palmsens.com you can obtain several sensors, including some sensors that can be used as a biosensor. The most important biosensors are:
WE Material: Platinum Surface Modification: Acetyl Cholinesterase Amount of WEs: 1 CE Material: Platinum RE Material: Silver<
WE Material: Platinum Surface Modification: Glucose Oxidase Amount of WEs: 1 CE Material: Platinum RE Material: Silver