Biological sensor, definition

Unfortunately, even with best efforts no one is yet able to provide a definitive value that a sensing system developer can use as the available concentration near a buried mine. It will continue to be necessary to develop more sensitive sensors. However, it also becomes increasingly valuable to use them more astutely, based on the behavior of the molecules as discussed here. Whether using artificial or biological sensors to search for buried explosives, a few things become apparent as important. Among them are ... 

For the purposes of establishing markets and describing the commercialization of chemical and biological sensor, it is first necessary to define these devices. For both types of sensor, the following general definition is used in this review ... 

Definition of integrated systems is more complex extension of chemical, biological and physical sensors. We can define integrated systems as optical or electrical (or hybride) measurement devices that exploit physical... 

The flow-through sensors described in this Section comply essentially with the definition of biosensor. This word, like every term used to designate devices of scientific and popular note, has been the object of a number of definitions of both generic and specific scope. In a broad sense, a biosensor is any instrument or technique that measures biomolecules. In stricter terms, Rechnitz defines a biosensor as "a device that incorporates a biochemical or biological component as a molecular recognition element and yields an analytical signal in response to biomolecules" [10]. In between these two... 

The present sensor could easily discriminate between some kinds of commercial drinks such as coffee, beer and aqueous ionic drinks (Figure 11) [22], Since the standard deviations were 2 mV at maximum in this experimental condition, these three output patterns are definitely different. If the data are accumulated in the computer, any food can be easily discriminated. Furthermore, the taste quality can also be described quantitatively by the method mentioned below. In biological systems, patterns of frequency of nerve excitation may be fed into the brain, and then foods are distinguished and their tastes are recognized [4-8]. Thus, the quality control of foods becomes possible using the taste sensor, which has a mechanism of information processing similar to biological systems. 

Although several definitions of biosensor exist, we will use the word to mean a microelectronic device that measures the interaction of an analyte with a biologically produced molecule as part of the measurement system. Figure 1 is a block diagram of a generalized biosensor. The most critical element of the sensor is the box marked Transducer this is where the information about the analyte (i.e. the... 

Biosensors can be defined as chemical sensor systems in which an analyte is detected based on biochemical processes or biochemical utilization. A biosensor is mostly composed of a biological element responsible for sampling and tracing, and a physical element called a transducer responsible for sample transmission and further processing (see also Part V, Chapters 8 and 9). The term biosensor does not really meet the lUPAC definition, in which sensors are defined to be self-containing, perform continuous monitoring and are reversible. For the purpose of this chapter, the term biosensor will not be so strictly used as in the traditional context. 

In this text, we distinguish between chemical sensors and biosensors according to the nature of their reactive surface. By this definition, chemical sensors utilize specific polymeric membranes, either per se or containing doping agents, or are coated with non-biological (usually low-molecular-weight) materials. These polymeric layers or specific chemicals, attached to the layers or directly to the transducer, interact with and measure the analyte of interest. The nature of the analyte or the reaction which takes place is not limited with such chemical sensors. 

Chapters 1 and 2 of Part A PREFACE introduce into definitions, classifications, history, properties and biological systems of macromolecular metal complexes. Then part B SYNTHESIS AND STRUCTURES contain at first in chapter 3 kinetics and thermodynamics of formation of these complexes. The following chapters 4 till 8 describe in detail the various synthetic routes for the preparation of macromolecular metal complexes. Part C with chapters 9 till 14 is devoted to PROPERTIES. The most important ones are binding of small molecules, physical and optical sensors, catalysis, photocatalysis and electron/photon induced processes. In chapter 15 few closing remarks are made. 

The assays described so far utilize UCNPs simply as labels but they can also be used for sensing chemical and biological parameters or analytes. According to [44], chemical sensors are miniaturized analytical devices that can deliver real-time and on-line information on the presence of specific compounds or ions in complex samples. Similar definitions do exist for biosensors [45]. There are additional definitions for sensors that also include more specific details like handiness, small size, operational and storage stability. One common criterion is the option of performing continuous and reversible measurements. However, this requirement is not always fulfilled, particular in the case of biosensors where binding constants are very high [46, 47]. 

Enzymes are biocatalysts with an extremely high selectivity. Their molecules are protein molecules with a molecular mass between 10 to 10 Da. Enzymes work under mild conditions, i.e. at room temperature or slightly above and at near-neutral pH. Biosensors with enzymes generally contain a layer of enzyme molecules immobilized at the sensor surface. This layer is able to catalyse just one reaction with a definite biologically active substance. The latter is recognized and determined specifically in this way. 

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