Optical sensor applications

Optical devices are preferentially integrated in optoelectronic circuits. State-of-the-art microfabrications, such as with LIGA technology, miniaturised laser diodes, etc., make sophisticated, small and rigid optical sensors and actuators possible. 

Imprinted polyurethanes as coatings for optrodes have been used for the detection of solvent vapours in air (see chapter 20). One per cent of substituted 3,3-diphenylphthalide as indicator has been intercalated within the polymer. The phthalide forms a highly coloured planar carbenium ion by interaction with an acidic component and a subsequent cleavage of the lactone ring - the unreacted phenolic groups in a polyurethane provide enough acidity for this reaction (Fig. 21.4). The incorporation of analytes reduces the acidity and the back-reaction 

Non-covalent molecularly imprinted sensors for complex mixtures 

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Nanosize particles (e.g., metals, semiconductors, etc.) are of continuing interest because they possess fascinating catalytic, electronic, and optical properties. Larger particles decorated with smaller nanoparticles on their surface are of interest because of their potential use as heterogeneous catalysts and their relevance in electronic and optical sensor applications as well as surface-enhanced Raman scattering [39,72-75]. 

Enzyme-based optical sensor applications will be further described in this book. They are still the most widespread optical biosensors but work is needed to overcome limitations such as shelf life, long term stability, in situ measurements, miniaturization, and the marketing of competitive devices. 

Optical Fibers. Pure and doped fused silica fibers have replaced copper lines in the telecommunication area. Fused silica fibers are used in laser surgery, optical sensor application, and laser welding (see Sensors). Optical-fiber-tethered weapons such as fiber-optics-guided (FOG) missiles are another potential application for fused silica (249,250) (see Fiber optics). 

Radhakrishnan J, El-Sherif MA (1996) Analysis on spatial intensity modulation for fiber optic sensor applications. J OptEiber Technol 2 114-126... 

Optical gas sensors generally have some characteristics such as a high insulating capacity, independence of electrical noises and operation in safety. Moreover it is possible for them to detect a variety of gases by choosing a gas sensing material. For environmental use of optical sensors, applications for NO , SOj, CO2 and CO are expected. 

Pt(ll) porphyrins are interesting dyes for optical sensor applications because they have long excited state lifetimes, large Stokes shifts, and room temperature phosphorescence [81, 113]. Fluorinated derivatives of Pt(ll) porphyrins show improved hydrophobicity and enhanced oxidative stability thus, they have been utilized as luminescent dyes. In addition, as was described previously, the use of pentafluorophenyl groups on the porphyrin meso-position has permitted the direct... 

Industrial Applications Gel coating/gel monolith for fiber-optic sensor applications ultrathin films ... 

Optical sensors and relay switches are used throughout the test routine for verification. For all possible problems, as well as the sequence in which they occur, the robot must recognize that there is a problem, define the problem, decide how best to resolve the problem, perform the necessary operations to overcome the problem, and enable the system to resume testing. This is an AI application area and a critical feature, mainly because the system operates unattended and measurements are taken overnight and during weekends. 

Many of those working on optical sensors have been overoptimistic. While many chemical sensors and biosensor have found applications in the laboratory and in research, they are much less often applied than physical sensors, e.g. those for temperature, pressure, velocity, or strain. This may be due to several factors, of which the following are considered to be most significant ... 

Peterson J.I., Vurek G.G., Fiber-optic sensors for biomedical applications, Science 1984 224 123. 

Culshaw B and Dakin J., Optical fiber sensors Applications, analysis, and future trends, Vol.4, Boston - London Artech House, 1997. 

Special optical fibres have been intensively investigated during recent years because of their potential wide-range use for on-line monitoring of material properties or processes in a number of areas of human activity (environment protection, food industry, medicine etc.) Their technology can be considered an integral part of the team-work on optical fibre sensors development. Despite special optical fibres represent a unique and often indispensable tool for a variety of sensor applications, special fibre production still represents only a small fraction of the market. Probably it is because of their low consumption (in comparison with standard telecommunication fibres), the need for much more advanced know-how and lower reproducibility. 

Narayanaswamy R., Wolfbeis O.S. (Eds.), Optical Sensors Industrial, Environmental and Diagnostic Applications, Springer Series on Chemical Sensors and Biosensors Vol. 

With regard to the development of infrared sensors during the last decade, some major fields of application can be identified, covering biological, biochemical or medical applications, environmental monitoring and process monitoring, with the latter being considered as the area closest to a widespread application of IR optical sensor systems. 

The continuous determination of compounds, which may adversely affect ecosystems and/or human health, is a major regulative and legislative goal of environmental protection nowadays. Considering the costs and efforts related to this task corroborates a clear demand for portable, real-time, in-situ, field applicable and cost-effective monitoring techniques. Due to their inherent properties, vibrational spectroscopic sensors, in particular fibre-optic sensors show a high potential to contribute to these applications. 

Optical sensors based on spectroscopy of guided waves have been demonstrated for detection and identification of numerous chemical and biological analytes. The choice of detection format for a particular application depends on the size of target analyte molecules, binding characteristics of available biomolecular recognition element, and range of analyte s concentrations to be measured. 

As a conclusion it has been demonstrated that optical sensors have a wide field of applications in the process control, surveillance and biosciences. They supply the chance to monitor processes an-line and with short time resolution. Interferometric sensors are rather sensitive and applicable in... 

Of course in defining application fields of certain types of 10 sensors they have to be compared with competitors in the terms of the market. Strong points of optical sensors are no EMI, potential of high sensitivity and spectral discrimination. The guided mode character adds to these no need of... 

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