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Systems designed by humans have no "intelligence" and only execute algorithms; however, they may, somehow, mimic an intelligent behaviour (smart systems). Since, at present, information management in the electrical energy domain is extremely advantageous, smart systems require, all together, sensors, actuators, and electronic interfaces. In literature there is some confusion, and even some contradiction, between the parameters used for characterizing the properties of sensors and of electronic interfaces. In the first part of the paper we provide a unified, coherent set of definitions which may be applied to both sensors and electronic interfaces. Afterwards we show how non-electrical systems may be conveniently analysed in the electrical domain by means of equivalent circuits, and we review some techniques for the design of high performance electronic interfaces; finally, we show a few examples, which illustrate the use of those techniques in practical applications

This paper introduces some preliminary consideration on non uniform resistance changes in silicon square photoconductors resulting when the surface exploration is made by small spot laser light. These results seem to be similar to those obtained from a chemically sensitive material such as, for instance SnO(2) left in air at a suitable temperature, for which the resistance decrease in presence of CO. A simple theory is considered for the determination of the approximated overall resistance value of a thermistor (or chemically sensitive thermistor) on the basis of sensitive sites localization.

The investigations on artificial olfactory systems in the last 20 years were basically concerned with the development of chemical sensors with selectivity properties similar to that of natural receptor. As a consequence, among the various features of olfaction emerged in the last two decades only the presumed non-selectivity of receptors is currently considered. Therefore, as physiology progresses enlighted the mechanisms of elaboration of signals in the olfactory pathways, artificial nose concept did not evolve much since its first conjecture. In this paper, an attempt to introduce artificial noses more adherent to recent views on olfaction is presented. The typical methodology of translation of conventional analog sensor signals into biologically similar spikes is applied to chemical sensors and a demonstration of the preservation of information sufficient for odour classification is given through a practical example.

Transport properties of a field effect transistor based on pentacene have been investigated by experimental and numerical analysis. Moreover, thin film transistors based on porphyrin have been realized and characterized. In order to derive from basic principles the transport properties of the organic semiconductors, we used a Monte Carlo (MC) simulator to calculate the field-dependent mobility. The overall device simulation is performed by using two-dimensional drift-diffusion simulations taking into account field-dependent mobility obtained from MC simulations, interface/bulk trap states and fixed charge density at the organic/oxide interface. We demonstrate how carrier mobility can be extracted from experimental device characteristics, without using the conventional MOSFET theory that could lead to the wrong result. Finally we demonstrate the realization of simple organic logic circuitry, namely an organic inverter with a different configuration of load transistor.

The development of artificial taste systems although devised since two decades has been hampered by the difficulties to find a material easily modifiable to form arrays of non-selective sensors endowed with sufficient cross-selectivities. On the other hand, materials with such features have been extensively studied for artificial olfaction systems. In particular, metalloporphyrins revealed interesting properties making them suitable for electronic nose development. In this paper, an investigation of the properties of glassy carbon electrodes modified with electropolymerised porphyrins is carried out. In particular, the study of the porphyrin structure to sensitivity relationship has been approached. Results confirm the behaviour observed with porphyrin-based gas sensors, namely the important role played by the metal atom in determining the sensor performances. An array of five glassy carbon modified electrodes was tested in a sample experiment aimed at discriminating among five compounds each belonging to a different basic taste class. Results shows that the taste discrimination is positively carried out for concentrations down to 10(-6) M. Obtained results are a reasonable basis to devise the development of artificial taste systems for a wide range of practical applications.

In this paper a sensor phase space is introduced and the analysis of trajectories in this space is proposed as a method to evaluate the sensor response. The phase space gives the opportunity to introduce a novel feature describing the area spanned by the trajectory during adsorption and/or desorption of chemicals from the sensor. A comparison with the usual features resulted in a better accuracy and a shortest measurement time.

We have studied the optical anisotropy of porphyrin layers with different thicknesses deposited onto gold substrates by the Langmuir-Schaefer technique. In coincidence with the Soret band of the molecule, the optical spectral line shape as determined by reflectance anisotropy spectroscopy exhibits a characteristic, large structure, which changes from a "peaklike" to a "derivative-like" shape at a well-defined thickness (8-10 monolayers). We interpret this result in the framework of electronic effects due to structural changes in the layers, yielding solid-state effects originating from the coupling of the pi orbitals of the porphyrin macrocycles.

A qualitative analysis of different kinds of green leaves brands employed in a popular Argentinean beverage—mate—was performed with an electronic nose (EN) based on quartz microbalance sensors. We employed a LibraNose from Technobiochip, which contains eight sensors. Two types of ‘odours’ are analysed for each sample corresponding to short- and long-term periods after the opening of the package. Principal component analysis (PCA) is applied to the sensor responses and it is possible to distinguish between different brands through their locus in the plane defined by the first two PCA components. Preliminary results confirm the usefulness of this EN for classification and future quality control purposes.

A dimeric structure that is held together by hydrogen bonds and is stable in solution is adopted by the hydrochloride salt of the expanded corrole shown. The synthesis, X-ray structure, and NMR and electronic absorption spectra of the new species all confirm the structural assignment in solution and in the solid state.

A survey network for congenital toxoplasmosis (TOXO-NET) was set up in December 1996 in Piedmont (Italy). Participants were asked to classify the infections in pregnant mothers and newborns by the criteria of the European Network on Congenital Toxoplasmosis published by Lebech in 1996. Because the IgG Avidity test is largely employed as a 2nd level test in toxoplasmosis diagnosis and it could be helpful to date infection, the co-ordinators of TOXO-NET suggested including it in the "case definition" of "probable" infection and "unlikely" infection. 117 cases of toxoplasmosis in pregnancy divided into the risk categories under Lebech's criteria were re-examined using the "new" case definitions. 77 out of 117 (65.8%) Toxoplasma gondii infections during pregnancy could be defined with only one serum sample using the IgG Avidity test. The IgG Avidity test proved a useful method to classify the Toxoplasma gondii infections in pregnancy, especially when we had only one serum sample.