Search

In this work, we investigate amperometric chemical sensor devices based on polyhedral oligomeric silsesquioxanes (POSS) nanocomposites. Devices, fabricated spinning the polymer on a substrate (glass, alumina), have been tested vs. ammonia, VOC and humidity. The devices exhibit a very strong, nicely reversible, response to water vapour. The operating mechanism at the base of the observed phenomena is explained in terms of a resonant charge transfer within the POSS cages enhanced by the water presence. The effect of the incorporation of other fillers such as carbon and zinc, has been also investigated in view of their possible use to improve sensor selectivity.

In this work, we present a hybrid multisensor system equipped with sensor fusion architectures for continuous gas concentration estimation, in a gas mixture scenario. Complex gas mixtures pose significant issues to quantification capability of room temperature operating sensors due to the often poor stability and selectivity of this class of devices. In this work, we show how these problems can take advantage by the use of pattern recognition algorithms. Here, the use of ad-hoc sensor fusion algorithms based on neural networks and support vector machines, together with an array of heterogeneous, room temperature operating sensors, is investigated to enhance array performances. Results obtained by different architectures for individual analyte quantification in NO2–NH3–humid air mixtures are presented and discussed. © 2007 Elsevier B.V. All rights reserved.

A new pressure sensitive paint (PSP) family, based on silicon nanostructured powders as luminophore, has been developed for application in stationary wind tunnel test and potential advanced turbomachinery purposes. The pressure sensitive paint operates on its photoluminescence quenching when the nanostuctured powder is exposed to an oxygen rich environment. Nanostructured powders, obtained with a combined ball milling—chemical etching process, are synthesized and deposited onto an appropriate polysilsesquioxane matrix, so that our paint can be adjusted for different pressure measurement applications. The formulation we propose is the first example of a PSP composite in which the filler acts as sensible element and it is localized over the polymeric film, reducing the response time due to oxygen variation to only a few seconds (0.5 ÷ 5 s).

A relative humidity (RH) sensor device based on n-type porous silicon has been designed, fabricated and characterized. The simple device is a diode reverse dc biased, exhibiting an extremely high sensitivity in ambient air and a large operating range (30–70% RH). Aging and NO 2 interference on the sensor performance have been also investigated.