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This study reports on the fabrication and characterization of an event detection subsystem composed of a flexible piezoelectric pressure sensor and the electronic interface to be integrated into an implantable artificial pancreas (IAP) for diabetic patients. The developed sensor is made of an AlN layer, sandwiched between two Ti electrodes, sputtered on Kapton substrate, with a preferential orientation along c-axis which guarantees the best piezoelectric response. The IAP is made of an intestinal wall-interfaced refilling module, able to dock an ingestible insulin capsule. A linearly actuated needle punches the duodenum tissue and then the PDMS capsule to transfer the insulin to an implanted reservoir. The device is located at the connection of the needle with the linear actuator to reliably detect the occurred punching of the insulin-filled capsule. Finite Element Analysis (FEA) simulations were performed to evaluate the piezoelectric charge generated for increasing loads in the range of interest, applied on both the sensor full-area and footprint area of the Hamilton needle used for the capsule punching. The sensor-interface circuit was simulated to estimate the output voltage that can be obtained in real operating conditions. The characterization results confirmed a high device sensitivity during the punching, in the low forces (0–4 N) and low actuator speed (2–3 mm/s) ranges of interest, meeting the requirement of the research objective. The choice of a piezoelectric pressure sensor is particularly strategic in the medical field due to the request of self-powered implantable devices which do not need any external power source to output a signal and harvest energy from natural sources around the patient.

Deposition of Au nanoparticles (NPs) through UV ultra-short-pulse laser ablation in vacuum is a methodology suitable for obtaining high purity supported plasmonic NPs with a superb adherence to both planar and patterned substrates. Furthermore, the peculiarity that upon sub-picosecond laser irradiation NPs form directly within the target leads to narrow and controlled size-distribution. While extensive literature theoretically models phase changes and pressure relaxation of metal targets under sub-picosecond irradiation, the evolution of the nanostructured deposit through different ablation regimes is poorly documented experimentally. In this paper, besides modeling the temporal evolution of electron and lattice temperature following sub-picosecond laser pulse irradiation of Au bulk at the threshold ablation fluence (0.1 J/cm2), we report an accurate statistical, morphological and structural characterization of the AuNP distributions as a function of the laser fluence tuned from 0.1 to 3 J/cm2 to drive the target through two ablation regimes. The occurrence of photomechanical spallation and phase explosion at low and high fluence, respectively, is correlated with the evolution of the NP deposits, which are discussed by providing a physical insight in the interplay between fluence-driven ablation regimes of the target, arrangement kinetics of the deposited species (NPs and vapour species) and (crystalline or amorphous) phase of the NPs. This knowledge is key for controlling the surface plasmon resonance response of AuNPs depending on the designed application.

Aluminum nitride (AlN) thin films were deposited by sputtering on Ti bottom electrodes and integrated on a kapton substrate for flexible and stretchable electronics. The aim of this work was to find the best combination of Ti underlayer sputtering conditions and AlN over-growth to obtain the (002) nitride orientation, fundamental requirement for the piezoelectric response of the material in piezoelectric devices. Flexible electronics represent today’s cutting-edge electronic technologies thanks to their low cost and easy fabrication scalability.

Summary The characterisation of traditional Italian pasta obtained by mixing amounts of toasted whole meal with re-milled semolina and other ingredients was obtained by means of physico-chemical, rheological, mechanical, sensory and image analyses. The toasted meal showed higher ash, fibre and protein contents than re-milled semolina. The replacement of percentages of re-milled semolina with the toasted meal and soft flour increased tenacity and decreased extensibility and strength, making the dough less suitable for pasta-making. The P/L values were indices of high starch damage. The replacement of part of re-milled semolina and water with toasted whole wheat meal, soft flour and eggs increased the optimal cooking time and the amount of water absorbed during cooking but made the other cooking parameters worse. The image analysis provided evidence of the changes induced by the use of toasted wholemeal, soft flour and eggs in the microscopic structure of pasta protein and starch.

A cheap nanofabrication process for titania (TiO2) polycrystalline nanowire array for gas sensing applications with lateral size ranging from 90 to 180 nm, and gas sensing characterizations are presented. Alternatively to typical pattern transfer techniques for submicron fabrication, authors focused on a standard 365 nm UV photolithographic process able to fabricate sol–gel nanostructured titania nanowires from a solid thin film. Main aim of present work is the experimental validation of enhanced gas sensing response of nanopatterned metal oxide thin film sensors. Two different kinds of gas sensor with nanopatterned sensitive area have been realized onto silicon substrates and tested towards different EtOH concentrations; experimental tests have been carried out with a contemporary output signals collection from a nanowires-based gas sensor and a second device with solid sensitive film without patterning, in order to validate effects of nanomachining on sensitive material response.

Organic–inorganic nano-hybrids, synthesized by supersonic molecular beams of TiO2 clusters and copper-phthalocyanine (CuPc) molecules, have been used to develop gas-sensing devices. This approach allows tailoring the properties of the synthesized materials and the interface between clusters and organic molecules so that new functional materials with interesting sensing properties are obtained. Two-layer hybrid devices with different architectures have been realized on alumina substrates with gold interdigitated electrodes. The hybrid films show an increase in conductivity up to a factor 6 compared to the pure CuPc depending on the architecture used. The response in terms of changes in conductivity towards non-oxidizing (methanol) species has been tested at different working temperatures. The hybrids show much higher sensitivity and stability with respect to CuPc grown with the same technique and they are already quite responsive at temperatures (75 °C) where the nanostructured TiO2 sensors are not at all functional. We ascribe these promising performances to the contribution coming from the n-TiO2–CuPc interfaces generated by the deposition process and we envisage the ability of the supersonic beam approach to produce novel classes of nano-hybrids in a variety of functional nanostructures.

Nanocrystalline NiO thin films were deposited by dc reactive magnetron sputtering in a mixture of oxygen and argon and subsequently coated by Au on a NiO film surface. Very thin Au overlayers with a thickness of about 1 and 7 nm have been prepared by magnetron sputtering. Then, the surface modified NiO films have been analysed by TEM, EDX and SEM. NiO thin films showed a polycrystalline structure with the size of nanocrystals ranging from a few nanometers to 10 nm. Electrical responses of NiO-based structure towards hydrogen have been measured.

Gas sensors research moves nowadays towards new applications of traditional metal oxide gas sensors into new fields like food quality, security applications and combustion control. Besides an implementation of this kind of transducers requires often a reduction of sensor dimensions, introduction of mature silicon technology substrates and fabrication methods. This work focuses on results obtained about implementation of reliable, selective, subtractive processes to perform high resolution patterning of different metal oxide films, deposited by cheap sol–gel technology onto oxidized silicon wafer or provided with thin layers of sputtered silicon nitride. Main innovations in this paper deal with an experimental evaluation of different methods to perform etching processes for three different sol–gel metal oxide materials deposited on standard dielectric layers, and evaluation of photoresist mask chemical inertness.

Cereals contaminated by toxigenic fungi can be analysed by detecting and quantifying the related mycotoxins by using complex extraction procedures and analytical techniques. In this work, we studied the complex headspace of wheat samples contaminated by Fusarium poae fungi by SPME-GC-MS, searching the presence of non-grain volatile metabolites due to fungi contamination and their temporal evolution after inoculation. The chemical information on the headspace composition of fungi-contaminated wheat samples were used for the analysis by an electronic nose, evaluating its discrimination ability among differently contaminated samples.

The possibility of utilizing semiconductor thin films based electronic nose for the detection of phosphine in post-fumigated grain for the control of quality of wheat products has been investigated. Undoped, Rh-, Ni- and Os-doped SnO2 thin films have been deposited by the sol-gel spin-coating method and their gas-sensing properties towards different concentrations of PH3 have been analyzed. The sensors were exposed to the volatiles of uncontaminated and differently fumigated cereal samples. The data coming from the response of the sensors have been elaborated by PCA method. The obtained results showed a very good capability of the array to discriminate different contaminated samples.

Nanocrystalline SnO2, In2O3 and In2O3–SnO2 thin films have been prepared by modified sol–gel methods making use of no-standard precursors and a suitable surfactant. The oxide thin films have been used as gas-sensing layers in chemoresistive gas sensors and their performances in the detection of nitrogen dioxide (2–20 ppm in dry air) have been analysed by electrical characterization in controlled atmosphere. The samples have been structurally and morphologically characterized by X-ray diffraction and SEM, respectively. Good gas-sensing responses towards NO2 have been found for all the prepared samples with improved performances for the In2O3–SnO2 based sensor. The performances of the sensors have been discussed according to the surface chemical reactions between the gas phase and the semiconductor.

Supersonic cluster beam deposition (SCBD) is used for fabrication of microsensors based on nanostructured titania layers. With a simple one-step post-deposition thermal treatment it is possible to modify the structural and electrical properties of the sensitive layers. Morphological, structural, and electrical characterisations are shown. The obtained sensors have very good performances in term of dynamic response to the exposure to methanol.

Herein we report the preparation of hybrid Co porphyrin-SnO2 thin films by sol-gel technique and a study of their sensing properties. The porphyrin structure bears a carboxylic group to improve its stabilization into the oxide matrix. SEM characterization of the spin-coated thin films deposited onto alumina substrates showed a homogeneously morphology. These CoTCPP-SnO2 sensors showed fast and reversible responses towards the detection of methanol vapors and highest responses were obtained at the working temperature of 250 degreesC. Optical characterization of the heated CoTCPP-SnO2 thin films indicated that the metalloporphyrin is still present after heating up to 320 degreesC, while it was completely decomposed after thermal treatment at 400 degreesC. These results support the presence of a catalytic effect of the CoTCPP at lower temperature, which induces a significant increase in the sensor responses at 250 degreesC, while at higher temperature, where the porphyrin is thermally decomposed, the hybrid CoTCPP-SnO2 sensors behave similarly to pure SnO2 devices. On the contrary, no significant differences in the sensor responses where observed in the case of CO detection, showing that metalloporphyrins can be used to modify the selectivity of SnO2 sensors.

This paper reports on the preparation, surface and electrical characterisation of titanium dioxide thin-films for highly selective gas sensor devices. Seeded supersonic beam deposition technique was used to prepare nanostructured thin films for gas sensors application. Two different typologies of sensors, prepared under different deposition conditions, were investigated. They showed gas-sensing properties comparable to most of the TiO 2 films realised with other more conventional techniques.

In this paper, a sensors array based on pure and doped SnO 2 sol–gel thin films used for the discrimination of different Mediterranean salami is presented. Principal component analysis (PCA) results have shown good discrimination of the clusters when applied to three different measurements typologies: (a) among different salami, (b) among samples of the same salami with different ripening and (c) among salami produced by male and female swine. Microbiological analyses, regarding micrococcaceae and lactobacilli growth, are, also, reported. Moreover, preliminary results obtained by static headspace/gas chromatography/mass spectrometry (SHS/GC/MS) analysis are shown.

In this work we show the capability of a sol–gel based electronic nose to be used in qualitative and quantitative analysis with the aim to recognize common volatile compounds usually present in the headspace of foods. Acetone, hexanal and 2-pentanone were chosen for this kind of measurements, performed both in dry air and in mixture of 50% humidity, just to simulate the experimental set-up in real applications. Moreover, different mixtures of 2-pentanone and hexanal at low concentration were investigated. We show how linear technique, such as principal component analysis (PCA) algorithm can be used for inspecting data distribution in simple cases like cluster discrimination. Moreover, non-linear techniques for difficult regression problems, such as artificial neural networks (multi-layer perceptron (MLP) and radial basis function (RBF)) are needed in particular for the prediction of different concentrations.

In this paper we present the study on gas sensing properties of TiO2 thin films grown by seeded supersonic beam of cluster oxides. Supersonic cluster beams, produced by a pulsed micro-plasma cluster source have been successfully used to prepare nanocrystalline thin films of TiO2. The obtained gas sensor devices, prepared by using different deposition parameters, were suitable for the use in a gas sensor array for electronic nose. Sensors showed a quite good response to ethanol, methanol and propanol. Principal component analysis was used as method for testing the array capability in discrimination and recognition of the volatile compounds.

In this paper, we report a specific application of a semiconductor thin films based sensor array for the discrimination of different olive oils. The active elements of the sensor array were undoped and Ni, Pd, Pt, Os-doped SnO thin films prepared by 2 sol–gel technique. Olive oil samples were randomly selected. They included commercial olive oils of different qualities (extravirgin, virgin and husk oils) and non-commercial local olive oils (deriving from different zone of the Salento region in Apulia) with different degrees of acidity. The sensor array coupled with a principal component analysis allows discrimination between different olive oils. In particular good separation between commercial and local products was obtained. 2002 Elsevier Science B.V. All rights reserved.

Pure and Ni-, Pt-, Pd-, Os-doped tin oxide and pure and Fe-doped indium oxide thin films have been prepared by the sol‐gel process. The microstructural properties of the as-prepared films have been investigated by means of X-ray diffraction (XRD). All the samples showed a polycrystalline structure that resulted to be dependent on the presence of the particular doping element. Integrated gas microsensor devices based on both pure and doped sol‐gel thin films of these two different metal oxides (SnO2 and In2O3) were realized. They were linked in an array configuration and exposed to the volatile compounds of different commercial olive oils samples in order to test the application of the array in an electronic nose for the discrimination among different commercial olive oils. The differently modified sensitive materials showed different sensing characteristics to the headspace of the olive oil, hence modulating the selectivity of the array. PCA analysis was performed on the array responses and the results showed the capability to discriminate olive oils of different quality. # 2002 Elsevier Science B.V. All rights reserved.

Titanium oxide nanofibers were successfully prepared via thermal treatment of electrospun composite polymer (PVP)/TiO2 nanofibers. The morphology and crystal structure were characterized by SEM and TEM. It was confirmed that the calcination process was responsible for the removal of PVP component and the growth of crystalline TiO2. The resulting nanofibers, which have a quite rough surface, an average diameter of 60 nm and a length reaching hundreds of μm, were found to be formed by the agglomeration of TiO2 nanoparticles with brookite phase. Gas-sensing tests towards ethanol demonstrated n-type sensing response and good reversibility at an operating temperature of 450 °C. A first tentative to model electrical impedance spectra was made in order to understand charge transport in relationship with morphological and structural aspects.

A poly-(3-hexylthiophene) (P3HT)/[6,6]-phenyl-C-61-butyric-acid-methyl-ester (PCBM) bilayer structure has been realized by single step matrix-assisted pulsed laser evaporation (ss-MAPLE) technique using the same solvent for both the polymers under vacuum conditions. Our ss-MAPLE procedure allows the fabrication of polymeric multilayer device stacks, which are very difficult to realize with the conventional solvent assisted deposition methods. A proof of concept bilayer P3HT/PCBM solar cell based on ss-MAPLE deposition has been realized and characterized. This demonstration qualifies ss-MAPLE as a general and alternative technique for the implementation of polymeric materials in hetero-structure device technology.

The optical response at room temperature of ZnO nanostructures, grown by controlled vapour phase deposition, to low concentrations of NO2 gas mixed in dry-air has been investigated. In particular the quenching in the emission signal, due to the interactions between oxidizing gas molecules and sample surface, has been monitored in excitonic and defect band, as a function of NO2 gas concentration. The dynamic responses and the resulting calibration curves, obtained for each emission band, have been compared. Furthermore responses of nanorods with different size and nanostructures with different exotic shape have been discussed in order to clarify the role of the morphology and/or dimensions and structural quality. In particular we have correlated the growth conditions and the resulting structural and optical properties of the samples, highlighting their role in the optical sensing response.

Gas sensors based on hybrid ZnPc–TiO 2 nanostructures, produced by molecules and clusters both deposited by supersonic beams, demonstrate enhanced properties in terms of sensitivity, stability and recovery times with respect to pure ZnPc. The hybrid sensors produced by successive deposition of the molecules and the TiO 2 clusters show the ability to detect reducing gases, such as methanol, to which the response of metal-phthalocyanines is quite poor. A mechanism based on the formation of chemical bonding, activated by the kinetic energy of the molecules and the strong reactivity of the inorganic clusters, is proposed as being at the basis of electron transfer occurring between the inorganic nanostructure and the molecule. This mechanism would explain the rise of new gas sensing properties of this novel class of nano-hybrid materials.

A cheap nanofabrication process for Titania (TiO2) polycristalline nanowire array for gas sensing applications with lateral size ranging from 90 to 180 nm, and gas sensing characterizations are presented. Alternatively to typical pattern transfer techniques for submicron fabrication, authors focused on a standard 365 nm UV photolithographic process able to fabricate sol-gel nanostructured titania nanowires from a solid thin film. Main aim of present work is the experimental validation of enhanced gas sensing response of nanopatterned metal oxide thin film sensors. Two different kind of gas sensor with nanopatterned sensitive area have been realized onto silicon substrates and tested towards different EtOH concentrations; experimental tests have been carried out with a contemporary output signals collection from a nanowires-based gas sensor and a second device with solid sensitive film without patterning, in order to validate effects of nano-machining on sensitive material response.

Fast and cheap nanofabrication process of titania (TiO2) nanowires array with lateral dimensions width ranging from 90 to 180 nm and 1.4 mm in length is presented. In spite of typical pattern transfer techniques for submicron fabrication, this work focused on a 365 nm UV photolithographic process to obtain long nanowires of sol-gel nanostructured titania onto silicon oxide mesa. TiO2 nanostrips-based array was electrically connected by sputtered platinum electrodes and tested towards different gases. A performance comparison within micromachined and solid thin film gas sensor was carried out.

A metal oxide sol-gel thin films based electronic nose to analyze different "single-cultivar" extra virgin olive oils is presented. In order to study a relation between the sensor responses and the real head-space of olive oil samples, analytical technique like headspace solid phase micro extraction\gas chromatography\mass spectrometry analysis was applied. The obtained GC-MS data were used to identify the particular compounds and characterize the chemical composition of the EVOOs samples. Statistical analyses were carried out on data obtained from electronic nose and GC-MS

Undoped and doped microsensors, based on tin oxide, have been prepared by the sol–gel deposition technique. The influence of the ageing of the Ti/Au interdigitated electrical contacts on the responses of the samples has been investigated. In particular, in this paper, are reported the responses of different sensors towards some gases and vapours, discussing the reproducibility, repeatability and the baseline drift during the measurements. SEM and XPS analyses of the samples were performed before and after the working period. The sensors showed a little drift, probably due to the ageing of the electrical contacts that was observed also in the SEM images. Obtained XPS results are in good agreement with SEM images.

Gas sensors have been prepared by using single crystalline MoO3 nanorods. Structures 50-150 nm and up to 15 mu m in length were synthesized by template directed hydrothermal synthesis. Gas sensing tests showed responses to NO2 up to 740% and to NH3 up to 570%. Moreover, preliminary electrical characterizations were performed, as a function of temperature in 20-520 degrees C range temperature, by means of current-voltage measurements. I-V dependence studies show a linear increase in current at low voltage and a quadratic increase at higher voltages. A study of the current-temperature dependence shows that at high temperature current is thermally active and successively decreases that can be explained by taking in account a change of material morphology.

The detection of aroma volatile compounds emitted by extra virgin olive oils (EVOOs) is of key importance in the quality control of this product. Physical–chemical techniques (GC, GC/MS, HPLC) and sensory analysis (panel test) are the classical methods used for this purpose, but they are expensive, time consuming, and do not allow on-line measurements. In this paper a new device, an Electronic Nose, that is a sensor array based on pure and doped SnO2 sol–gel thin films used for the discrimination of different Mediterranean “single-cultivar” EVOOs, was presented. To confirm the sensor array responses, analytical technique like headspace-solid phase micro-extraction/gas chromatography/mass spectrometry (HS-SPME/GC/MS) analysis was applied to the analysis of volatiles compounds in EVOOs samples. Moreover sensory analysis on EVOOs was carried out. The obtained GC/MS data were used to identify the particular compounds and characterize the chemical composition of the EVOOs samples. In addition a chemometric pattern recognition technique was used for multivariate data analysis. The variations in the GC/MS fingerprint of the different samples were analysed using principal component analysis (PCA). Statistical analyses were carried out on data obtained from Electronic Nose, GC/MS and sensory analysis. © 2005 Elsevier B.V. All rights reserved.

In this work we describe the design implementation, validated by experimental results, of an innovative gas sensor array for wine quality monitoring. The main innovation of this integrated array deals with the simultaneous outputs, from a single chip on custom SMD socket, of eight different signals coming from a WO 3 thin film structure heated in a linear temperature gradient mode, allowing an overall evaluation of gas sensing properties of the material in a 100 °C-wide window, typically from 300 to 400 °C. The implemented sensitive layer is a WO 3 film deposed by RF-sputtering. Preliminary tests of gas sensing showed good responses to the target analytes for the specific application (1-heptanol, 3-methylbutanol, benzaldehyde and ethyl-hexanoate).

In this work, we describe the design implementation, validated by experimental results, of an innovative gas sensor array for wine quality monitoring. The main innovation of this integrated array deals with the simultaneous outputs, from a single chip on TO-12 socket, of 8 different signals coming from a WO3 thin film structure heated in a linear temperature gradient mode, allowing an overall evaluation of gas sensing properties of the material in a 100°C-wide window, typically from 300 to 400°C. The implemented sensitive layer is a WO3 film deposed by RF-sputtering. Preliminary tests of gas sensing showed good responses to the target analytes for the specific application (1-heptanol, 3-methyl butanol, benzaldehyde and ethyl-hexanoate).

Semiconductor sensors based on nanocrystalline SnO2, In2O3 and In2O3–SnO2 thin films have been investigated for detecting low concentration (2–20 ppm) of nitrogen dioxide in dry air. In this work the gas-sensitive layers were prepared by modified sol–gel methods making use of non-standard precursors and a suitable surfactant. The samples have been structurally and morphologically characterized by X-ray diffraction and SEM, respectively. Good gas-sensing responses towards NO2 have been found for all the prepared samples with improved performances for the In2O3–SnO2 based sensor. The performances of the sensors have been discussed according to the surface chemical reactions between the gas phase and the semiconductor.

We report the fabrication of libraries of nanostructured TiO2 films with a gradient in nanoparticle crystalline phase and dimensions. By supersonic cluster beam deposition it is possible to produce rutile nanoparticles with a diameter smaller than 10 nm and to spread them into a co-deposited amorphous titania matrix. Upon thermal annealing rutile nanocrystals act as growth seeds of a film with a spatially controlled rutile/anatase ratio. Films with controlled crystalline phase variation have been deposited on micropatterned substrate to produce arrays of chemoresistive sensors of volatile organic compounds. Devices with different nanocrystalline structures and performances are obtained by a simple one-step thermal treatment after deposition.

This paper gives an overview about the principles and the technologies used in solid-state gas sensors. These devices work by measuring a physical property changed by adsorption/desorption processes and chemical reactions on the surface of a sensing element, i.e. a solid-state film of a gas-sensitive material. Some of the most used types of solid state gas sensors are here described together with novel sensor technologies in development for commercial exploitation in the future.

Undoped and doped tin oxide-based microsensors have been prepared by the sol-gel deposition technique. The influence of the ageing of the Ti/Au interdigitated electrical contacts on the responses of the samples has been investigated. In particular, in this paper, we report the responses of different sensors towards some gases as hexanal, acetone and pentanal discussing the reproducibility and repeatability and the baseline drift during the measurements. The sensors showed a little drift probably due to the ageing of the electrical contacts that we observe by SEM images. SEM results were also correlated with XPS analysis.

Thin films in the SnO2-In2O3 system, with relative concentrations of the two oxides ranging from 2% to 98% (molar percentage of the oxide), were deposited by sol-gel and solution processes. The films for the physical characterizations were deposited onto oxidized silicon substrates, while the films for the gas-sensing tests were deposited onto alumina. The starting solutions were characterized by FTIR spectroscopy, while the films on silicon, heated at various temperatures, were characterized by X-ray diffraction and SEM observations. The interaction between the two systems is particularly evident in the case of the system described by a 50% In2O3-50% SnO2 nominal composition. The crystallization on In2O3 during the film heat-treatment hinders the crystallization of SnO2, thus Sn is dispersed as an n-dopant in the In2O3 lattice, indeed showing a current signal, in the gas-sensing test, two orders of magnitude higher than the pure film. The response of the mixed-oxide based device to NO2 is better than pure In2O3. On the other hand, the response (relative resistance change) of pure SnO2 to low (from 0.1 to 1 ppm) NO2 concentrations ranges from 150 to 300, a result that can be correlated with the nanostructure of the film, which, from SEM and XRD results, seems constituted by very small grains.

Hybrid CoTPP-SnO2 thin films have been obtained by the sol-gel approach coupled with spin coating technique. These films have been deposited onto interdigital electrodes and their performances as chemical sensors have been measured towards the detection of methanol vapors. These CoTPP-SnO2 sensors showed fast and reversible responses towards different concentrations of methanol and best results were obtained at 250 degrees C working temperature, while a sharp decrease was observed at higher temperatures. These results are attributed to the well known catalytic activity of metalloporphyrins, which is not thermally decomposed at 250 degrees C, as confirmed by optical measurements.

We report on the preparation and characterization of titanium dioxide thin film gas sensor devices for application in lambda measurement. The sensor responses to different oxygen concentrations have been analyzed. Moreover, according to a computing software that simulates the composition of exhaust gases for different λ values, we exposed the sensors to different complex mixtures of exhaust gases, calibrating in such a way the sensor for the measurement of lambda.

This work reports on the use of two innovative techniques in the field of gas sensors for preparing nano-structured materials: sol–gel and supersonic cluster beam deposition. By means of sol–gel, nano-structured In 2 O 3 thin films have been prepared and deposited under different deposition parameters on silicon wafer. In this way the results have shown a good compatibility of the method with silicon technology, then potentially suitable to be used in the fabrication of integrated devices. The second technique has been applied for the preparation of nano-structured TiO 2 thin films showing its capability to be used in the fabrication of gas sensor devices, mainly when a good control of the grain dimension is required.

In this paper, a sensors array based on pure and doped SnO2 sol-gel thin films used for the discrimination of different Mediterranean salami is presented. Principal Component Analysis (PCA) results show good discrimination between different salami, between salame with different ripening and between salami produced by male and female swine. Microbiological analysis regarding micrococci and lactobacilli growth are, also, reported. Moreover Static Headspace\Gaschromatography\Mass Spectrometry (SHS\GC\MS) analysis are in progress to better understand and correlate the biological compounds analysis with the volatile ones of different salami.

In this paper, we present the first sensor ever built using films grown by supersonic beam of cluster oxides as sensing material. Supersonic cluster beams, produced by a pulsed micro-plasma cluster source have successfully used to prepare nanocrystalline thin films of TiO/sub 2/. The sensors, prepared by using different deposition parameters, were suitable for use in a gas sensor array for electronic nose. Sensors showed a quite good response to ethanol, methanol and propanol. Principal component analysis was used as method for testing the array capability in discrimination and recognition of the volatile compounds.