Photoluminescent sensors

Although these are the most common gas sensors, technology is changing daily and many different materials with different properties are currently being developed. The potential of many new sensors for detecting fragrances is normally reported in scientific articles. For example, Letant et al. (2(X)0) used an array based on photoluminescence sensors to detect flavours, where the photoluminescence of the porous silicon films is quenched by the presence of gas, so a gas sensor is obtained. On the other hand, Battiston et al. (2001)... 

L6tant et al. (2000) have compared the discrimination ability of an array composed by photoluminescence sensors based on porous siUcon films. An array of these sensors was connected in series with a commercial electronic nose, and the discrimination ability was compared for samples of citnis/dx-3-hexenal, ethyl cinnamate and ethyl valerianate, with good performance for the silicon array. 

Zinc carboxylate interactions have been exploited as part of a fluorescent molecular sensor for uronic acids. The sensors feature two interactions coordination of the carboxylate to the zinc and a boronic acid diol interaction.389 Photoluminescent coordination polymers from hydrothermal syntheses containing Zn40 or Zn4(OH)2 cores with isophthalate or fumarate and 4,4 -bipyridine form two- and three-dimensional structures. Single X-ray diffraction of both dicarboxylates identified the network structure.373... 

Nickel AML, Seker E, Ziemer BP, Ellis AB. Imprinted poly (acrylic acid) films on cadmium selenide. A composite sensor structure that couples selective amine binding with semiconductor substrate photoluminescence. Chem Mater 2001 13 1391-1397. 

The position of the maximum in the photoluminescence spectra is independent of the oxidant type and appears at A, 625 mn. The method of chemical etching is most adapted to mass manufacturing and it is currently used for the preparation of thin homogeneous luminescent layers of sNPS for sensor devices. 

By controlling the structural and electronic properties of sNPS which are related to the nanocrystallite dimensions and porosity, their surface selectivity and sensitivity to different gases (nitrogen and carbon oxide, vapors of water and organic substances) can be adjusted. This approach for the effective detection of acetone, methanol and water vapor in air was described in [13-15].The minimal detectable acetone concentration was reported to be 12 pg/mL. Silicon sensors for detection of SO2 and some medicines such as penicillin were created [16-18]. sNPS were used for the development of a number of immune biosensors, particularly using the photoluminescence detection. Earlier we developed similar immune biosensors for the control of the myoglobin level in blood and for monitoring of bacterial proteins in air [19-23]. 

Fig. 9.8 The dependence of the sNPS immune sensor photoluminescence (PhL) signal on the concentration of T2 mycotoxin in solution...

Starodub NF, Starodub VM (2004) Biosensors based on the photoluminescence of porous silicon overall characteristics and apphcation for the medical diagnostics. Sensors Electronics and Microsystem Technol 2 63-83... 

Starodub VM, Fedorenko LL, Starodub NF (1998) Control of a myoglobin level in solution by the bioaffine sensor based on the photoluminescence of porous sihcon. In Proceedings of the european conference on solid-state transducers and 9th UK conference on sensors and their apphcations, Southampton, UK, 2 817-820, 13-16 Sept 1998... 

In principle, optical chemosensors make use of optical techniques to provide analytical information. The most extensively exploited techniques in this regard are optical absorption and photoluminescence. Moreover, sensors based on surface plasmon resonance (SPR) and surface enhanced Raman scattering (SERS) have recently been devised. 

Figure 13.16 Variation of the fluorescence intensity of Eu-35 at 619 nm under alternating streams of air saturated with ethanol (signal intensity decreases) and ethanol-free air (signal intensity increases) [56]. (Reproduced with permission from B.V. Harbuzaru et ah, Metal-organic nanoporous structures with anisotropic photoluminescence and magnetic properties and their use as sensors, Angewandte Chemie International Edition, 2008, 47, no. 6, 1080-1083. Wiley-VCH Verlag Gmbh Co. KGaA.)...

Fig. 16.15. Photoluminescence spectra of derivatized porous silicon microcavity sensors treated with B. subtilis (Cram-(+), left spectra) or E. coli (Cram-(—), right spectra) lysates. In the top two spectra, the dark lines correspond to measurements before treatment with the bacteria the grey spectra are those obtained after treatment. The bottom two spectra plot...

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