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Bio-FETs couple a transistor device with a bio-sensitive layer that can specifically detect bio-molecules such as nucleic acids and proteins. A Bio-FET system consists of a semiconducting field-effect transistor that acts as a transducer separated by an insulator layer (e.g. SiO 2) from the biological recognition element (e.g. receptors or probe molecules) which are selective to the target ...
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Biosensors used for screening combinatorial DNA libraries. In a biosensor, the bioreceptor is designed to interact with the specific analyte of interest to produce an effect measurable by the transducer. High selectivity for the analyte among a matrix of other chemical or biological components is a key requirement of the bioreceptor.
3D Sarfus image of a DNA biochip. The microarray—the dense, two-dimensional grid of biosensors—is the critical component of a biochip platform. Typically, the sensors are deposited on a flat substrate, which may either be passive (e.g. silicon or glass) or active, the latter consisting of integrated electronics or micromechanical devices that perform or assist signal transduction.
Various materials can be made into the transduction element, including silver, gold, graphite or nanoparticle variations of such materials. Detection of electrochemical property changes allows for real-time analysis and kinetics data, an advantage biosensor methods such as optical biosensors lack.
An electro-switchable biosurface is a biosensor that is based on an electrode (often gold) to which a layer of biomolecules (often DNA molecules) has been tethered. An alternating or fixed electrical potential is applied to the electrode which causes changes in the structure and position (movement) of the charged biomolecules.
A number of paper-based biosensors have been developed, which use a variety of approaches. [5] In general, pathogens are detected via colorimetric, electrochemical, fluorescent, and chemiluminescent detection, though there are other types of sensors as well. [3] Several examples of paper-based biosensors are described below.
Amperometric biosensors have been used in bio-MEMS for detection of glucose, galactose, lactose, urea, and cholesterol, as well as for applications in gas detection and DNA hybridization. [11] In potentiometric biosensors, measurements of electric potential at one electrode are made in reference to another electrode. [ 11 ]