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Definition: biosensor from Merriam-Webster's Collegiate(R) Dictionary

(1962) : a device that monitors and transmits information about a life process; esp : a device consisting of a biological component (as an enzyme or bacterium) that reacts with a target substance and a signal-generating electrochemical component that detects the resulting products or by-products

Summary Article: biosensor
From The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide

Device based on microelectronic circuits that can directly measure medically significant variables for the purpose of diagnosis or monitoring treatment. One such device measures the blood-sugar level of diabetics using a single drop of blood, and shows the result on a liquid crystal display within a few seconds.

Biosensors typically contain three separate functional parts: the sensor recognizing the target, the detector providing the response or readout, and a transducer to allow communication between these two. Target recognition in biosensors is typically achieved by a biomolecule, such as an antibody, a receptor, an enzyme, or a nucleic acid. This biomolecule will typically be immobilized, that is, firmly linked to a solid support. The readout can be an electronic signal to be shown on an LCD display or via a computer. Optical signals can be converted into electronic ones by suitable detectors. It can also be a colour reaction to be checked by eye or by spectrometry. Ideally, a biosensor should be small, portable, and user-friendly even for untrained users. Home pregnancy-test kits are the most common example of such a biosensor.

The pregnancy test requires several biomolecules. The target, namely pregnancy-specific hormones in the urine, is first bound by immobilized antibodies located within the readout window. A second antibody, carrying an enzyme that will produce the colour reaction, then binds to the immobilized antibody-hormone complex.

In the laboratory, the widely used ELISA technique (see enzyme-linked immunosorbant assay), is based on a similar chain of molecular recognition events.

© RM, 2018. All rights reserved.

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