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An integrated device consisting of a biological recognition element and a transducer capable of detecting the biological reaction and converting it into a signal which can be processed. Ideally, the sensor should be self-contained, so that it is not necessary to add reagents to the sample matrix to obtain the desired response. There are a number of analytes (the target substances to be detected) which are measured in biological media: pH, partial pressure of carbon dioxide (pCO2), partial pressure of oxygen (pO2), and the ionic concentrations of sodium, potassium, calcium, and chloride. However, these sensors do not use biological recognition elements, and are considered chemical sensors. Normally, the biological recognition element is a protein or protein complex which is able to recognize a particular analyte in the presence of many other components in a complex biological matrix. This definition has since been expanded to include oligonucleotides. The recognition process involves a chemical or biological reaction, and the transducer must be capable of detecting not only the reaction but also its extent. An ideal sensor should yield a selective, rapid, and reliable response to the analyte, and the signal generated by the sensor should be proportional to the analyte concentration.

Biosensors are typically classified by the type of recognition element or transduction element employed. A sensor might be described as a catalytic biosensor if its recognition element comprised an enzyme or series of enzymes, a living tissue slice (vegetal or animal), or whole cells derived from microorganisms such as bacteria, fungi, or yeast. The sensor might be described as a bioaffinity sensor if the basis of its operation were a biospecific complex formation. Accordingly, the reaction of an antibody with an antigen or hapten, or the reaction of an agonist or antagonist with a receptor, could be employed. In the former case, the sensor might be called an immunosensor.

Since enzyme-based sensors measure the rate of the enzyme-catalyzed reaction as the basis for their response, any physical measurement which yields a quantity related to this rate can be used for detection. The enzyme may be immobilized on the end of an optical fiber, and the spectroscopic properties (absorbance, fluorescence, chemiluminescence) related to the disappearance of the reactants or appearance of products of the reaction can be measured. Since biochemical reactions can be either endothermic (absorbing heat) or exothermic (giving off heat), the rate of the reaction can be measured by microcalorimetry. Miniaturized thermistor-based calorimeters, called enzyme thermistors, have been developed and widely applied, especially for bioprocess monitoring.

In the case of affinity biosensors, as is true of catalytic biosensors, many physical techniques can be used to detect affinity binding: microcalorimetry (thermometric enzyme-linked immunosorbent assay, or TELISA), fluorescence energy transfer, fluorescence polarization, or bioluminescence.

The quality of the results obtained from sensors based on biological recognition elements depends most heavily on their ability to react rapidly, selectively, and with high affinity. Antibodies and receptors frequently react with such high affinity that the analyte does not easily become unbound. To reuse the sensor requires a time-consuming regeneration step. Nonetheless, if this step can be automated, semicontinuous monitoring may be possible.


(analytical chemistry)
An analytical device that converts the concentration of an analyte in an appropriate sample into an electrical signal by means of a biologically derived sensing element intimately connected to, or integrated into, a transducer.


A device that detects a person's body movement, temperature, pulse rate and other physical characteristics, which it converts into electronic signals. See lab on a chip, smart clothes, biowearable and data glove.
References in periodicals archive ?
Biosensors have also shown a huge potential for commercialization in other fields of application such as biosensor-based instruments in environmental sampling and food and beverage production as well as in non-invasive instruments for clinical analysis.
This combined funding will propel VitalConnect's commercialization of the HealthPatchMD and VitalPatch biosensors for patient monitoring in the hospital and at home.
We are very excited about this DES agreement with Biosensors, because it represents our strong commitment to expand our product portfolio to support the demands in cardiovascular care today," said David Wilson, president of Cordis, a Cardinal Health company.
DNA sequence of salmonella bacterium was stabilized on glass carbon nanoporous electrode, and the final biosensors were used to measure the bacteria in the food sample.
ISLAMABAD -- Iranian researchers produced a new type of enzyme biosensor to increase the speed of clinical diagnosis.
They follow with a detailed discussion of impedimetric biosensors and the principles of electrochemical impedance spectroscopy.
Researchers at Swansea University have developed a graphene biosensor so sensitive it can detect molecules that show signs of increased cancer risk.
Furthermore we investigated whether these biosensors can be used to determine glutamine level in several real samples.
In a series of detailed studies of specific areas, specialists at the interface between electronic technology and medicine provide an overview of biosensors from the perspectives of principles and transduction approaches and medical applications.
Alocilja's work focuses on nanostructured biosensors, sensors that use biological receptors--antibodies, enzymes, and nucleic acids--to detect the presence of specific pathogens.
The time required for lactose determination with biosensors depends on the bio-recognition element as well as the construction and properties of the applied signal transducers and it can vary from a few minutes to several hours.