Optical sensing properties

Rella R., Siciliano P., Capone S., Spadavecchia ., Ciccarella G., and Vasapollo G., Optical sensing properties of phthalocyanines thin films in array configuration and their application in VOCS detection, pp. 115-120, Sensors and microsystems. Proceedings of the 8th Italian Conference, Trento, Italy, 12-14 February 2003. 

PIM-l thin films exhibit excellent optical sensing properties by changing their color on adsorbing organic vapor, even at very low concentration (Figure 10.12). Although the performance of a fiber-optic spectrometer is better than this, for PIM-l the hindrance effect due to humidity is less due to the hydrophobicity. The microporous nature, as well as the behavior towards solvent, is the key to fabricate sensor-based devices with PIMs. ... 

Chapron J, Alekseev SA, Lysenko V, Zaitsev VN, Barbier D (2007) Analysis of interaction between chemical agents and porous Si nanostructures using optical sensing properties of infra-red Rugate filters. Sens Actuators B 120 706-711... 

Optical sensors rely on optical detection of a chemical species. Two basic operation principles are known for optically sensing chemical species intrinsic optical property of the analyte is utilized for its detection indicator lor label) based sensing is used when the analyte has no intrinsic optical property. For example, pH is measured optically by immobilizing a pH indicator on a solid support and observing changes in the absorption or fluorescence of the indicator as the pH of the sample varies with time1 20. 

Optical sensing in general is based on changes of the optical properties of materials within the optical circuitry due to changes in the environment. 

Many compounds exhibit near-IR and mid-IR absorption. By using IR transparent optical fibers, detection of an absorption band in the IR region is possible for optical sensing. Both direct sensing using the absorption property of the analyte or indicator sensing are widely exploited. Most mid-IR sensing schemes are based on the principles of internal reflection spectroscopy, or the attenuated total reflection (ATR) [3,14-21],... 

Metal nanoparticles have extraordinary size-dependent optical properties, not present in the bulk metal and have, consequently, been the subject of intense research during the past decade or so.27 Attention has recently focused on functionalising colloidal nanoparticles with molecular recognition components for potential sensing applications.28,29,30 We have prepared a new amido-disulfide functionalised zinc metalloporphyrin (8) which was self-assembled on to gold nanoparticles to produce a novel anion-selective optical sensing system (9) (Scheme 3).4... 

Because of their electrical, optical, and redox properties as well as the thermal and chemical stability, the Pcs also have been tried in the detection of volatile organic compounds and poisonous gases, which is very important for environment and human health. In the past decades, the possible applications of Pc thin film as sensor for atmospheric gaseous pollutants have been extensively studied [73, 74], Langmuir-Blodgett films of some multinuclear and multidouble-decker lutetium Pcs have also been used for those measurements [75,76], More details about conductivity and sensing properties of Pcs can be found elsewhere [77,78]. 

This chapter highlights examples of emerging applications of combinatorial approaches in analytical chemistry, the advantages, and drawbacks. As we have reviewed this general area recently,6 to maintain a reasonable scope, we focus upon methodologies that involve development of materials with molecular recognition properties for optical sensing. 

It is known that the advantages of imprinted ormosils (organically modified silanes) over acrylic-based MIPs are their chemical stability, the high thermal stability of sol-gel materials, synthesis in mild temperature conditions, optical transparency, photo-, electro- and chemical stability, all properties that made these materials ideal for use in optical sensing approaches, particularly in aqueous samples.48 50 Although... 

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