Papers by Simonetta Capone
Sensors and Microsystems, 2001
The transparent titanium-zirconium-containing gel was obtained using heteroligand coordination co... more The transparent titanium-zirconium-containing gel was obtained using heteroligand coordination compounds (namely, alkoxoacetylacetonates) as the precursors. The high-dispersive system "ZrTiO 4-carbon", formed after drying of such gel and carbonization of the obtained xerogel, was used to study the evolution of microstructure for the product (ZrTiO 4) during thermal treatment in air for 1 hour in the temperature range from 500ºC to 1000ºС. It was stated that the formation of crystalline phase occurred in the narrow range 690-730ºС. The thermal treatment at 500ºC and 600ºС allowed obtaining micro-and mesoporous X-ray amorphous products of the composition ZrTiO 4 , with the specific surface area falling in the range 82-150 m 2 /g. At the higher temperatures the single-phase nanocrystalline powder was prepared (the specific surface area
Sensors and Microsystems, 2002
ABSTRACT
Proceedings of IEEE Sensors 2003 (IEEE Cat. No.03CH37498)
Cluster supersonic beams have been previously shown to be a viable method to produce nanostructur... more Cluster supersonic beams have been previously shown to be a viable method to produce nanostructures by assembling them on a substrate in a controlled way. Control of precursors properties in the beam efficiently determine morphology, structure of films and their functional properties. Sensors based on cluster assembled TiO2 show remarkable properties (sensitivity, response time and selectivity). We expand this approach
There is currently a great interest in developing new techniques for food quality assessment. Ele... more There is currently a great interest in developing new techniques for food quality assessment. Electronic nose is considered an attractive technique for evaluating food aroma. In this work we present an overview of application examples of an electronic nose based on sol-gel metal oxide gas sensor array for the assessment of some foodstuffs (milk, olive oil and peach fruit). The responses of the sensor array to the flavours of these foodstuffs have been correlated with the results obtained by other standard techniques. Resumen Existe actualmente un gran interés en desarrollar nuevas técnicas para la valoración de la calidad de alimentos. La nariz electrónica se considera una técnica atractiva para evaluar el aroma de alimentos. En este artículo presentamos una descripción de los ejemplos del uso de una nariz electrónica basada en un arreglo de sensores de gas del tipo óxido de metal (obtenido por el método de sol-gel) aplicados a algunos comestibles (leche, aceite de oliva y duraznos). La respuesta de la matriz de sensores a los aromas de los alimentos ha sido correlacionada con los resultados obtenidos por otras técnicas estándares.
We report on the potentiality of the Matrix-Assisted Pulsed Laser Evaporation (MAPLE) technique f... more We report on the potentiality of the Matrix-Assisted Pulsed Laser Evaporation (MAPLE) technique for the deposition of thin films of colloidal nanoparticles to be used for gas sensors based on electrical transduction mechanisms. The MAPLE technique seems very promising, since it permits a good thickness control even on rough substrates, generally used to enhance the active surface for gas adsorption. TiO2 (with a capping layer of benzyl alcohol) and SnO2 (with a capping layer of trioctylphosphine) colloidal nanoparticles were diluted in suitable solvents (0.2% concentration), frozen at liquid nitrogen temperature and ablated with a ArF (lambda=193 nm) or KrF (248 nm) excimer laser. The nanoparticle thin films were deposited on silica, interdigitated alumina and Si substrates and submitted to morphological (SEM-FEG), structural (XRD, FTIR), optical (UV-Vis transmission) and electrical (sensing tests) characterizations. A uniform distribution of TiO2 nanoparticles, with an average size of ~10 nm, was obtained on flat and rough substrates. The deposited TiO2 nanoparticles preserved the anatase crystalline structure, as evidenced by the XRD spectra. FTIR analysis showed that the SnO2 nanoparticles maintained the capping layer after the laser-assisted transfer process. This protective layer was removed after annealing at 400 °C. The starting nanoparticle dimensions were preserved also in this case. Electrical tests, performed on TiO2 nanoparticle films, in controlled atmosphere in presence of ethanol and acetone vapors, evidenced a high value of the sensor response even at very low concentrations (20-200 ppm in dry air). In contrast, in the case of SnO2 nanoparticle films, electrical tests to ethanol vapor presence showed poor gas sensing properties probably due to the small nanoparticle sizes and interconnections.
ABSTRACT An approach for the evaluation of sensor array efficiency is proposed. The reproducibili... more ABSTRACT An approach for the evaluation of sensor array efficiency is proposed. The reproducibility of sensor responses and the uniqueness of chemical images (CI) formed by the array are considered as dominant factors that determine sensor array functionality. The key feature of the method is representation of array response as a numerical function of sensors responses. This allow making mathematical operations with CI. The dispersion of CIs of given set of analytes can serve as a measure of their uniqueness. The coefficient of covariance in the set of measurements expresses their reproducibility. The rate of influence of both reproducibility and CI uniqueness on the discriminating ability is shown qualitatively on the example of three QCM sensor array with metal phthalocyanines sensitive coatings. The illumination of sensors surfaces in the Q‐band region of Pc’s adsorption spectra was applied as a factor affecting both the reproducibility and the uniqueness of CIs.
2008 IEEE Sensors, 2008
Abstract In this work we proposed a system based on metal oxide gas micro-sensors to estimate di... more Abstract In this work we proposed a system based on metal oxide gas micro-sensors to estimate diesel or gasoline contamination in different engine oil samples. The gas-sensing layers (undoped, Pt, Pd, Rh-doped SnO2, In2O3 and mixed In2O3-SnO2) have been ...
IEEE Sensors, 2005.
A metal oxide sol-gel thin films based electronic nose to analyze different &... more 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 extractiongas chromatographymass spectrometry analysis was applied. The obtained GC-MS data were used to identify the particular
Sensors and Microsystems, 2004
ABSTRACT At current there is a great interest in developing new techniques for the food quality a... more ABSTRACT At current there is a great interest in developing new techniques for the food quality assessment. Electronic nose is considered an attractive technique for evaluating food aroma. In this work we present an overview of application examples of an electronic nose based on sol-gel metal oxide gas sensor array to the evaluation of some foodstuffs (milk, dry salami, olive oil and peach fruit). The responses of the sensor array to the flavours of these foodstuffs have been correlated with the results obtained by other standard techniques.
Thin Solid Films, 2002
In this paper, we report a specific application of a semiconductor thin films based sensor array ... more 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.
Sensors and Actuators B: Chemical, 2004
This paper reports on the preparation, surface and electrical characterisation of titanium dioxid... more 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 ...
Sensors and Actuators B: Chemical, 2004
Organic thin films based on a blend of two types of metal-coordinated macromolecules, i.e. Zn(II)... more Organic thin films based on a blend of two types of metal-coordinated macromolecules, i.e. Zn(II) tetra-4-(2,4-di-tert-amylphenoxy)phthalocyanine (ZnPc) and Cu(II) tetrakis(p-tert-butylphenyl)porphyrin (CuP) have been deposited by spin-coating and used as optical chemically interacting materials for the detection of methanol, ethanol and isopropanol vapours. This paper reports the use of a specific optical technique consisting of the selection of four specific spectral regions taken in the UV-Vis spectral range corresponding to the typical Q and Soret bands of the phthalocyanine and porphyrin macromolecules and their corresponding blends. The variations in the absorption peaks obtained by the exposure of the single ZnPc and CuP sensing layers to the considered vapours in controlled atmosphere have been analysed and compared with those derived from a thin film obtained by mixing the two metal complexes in an appropriate ratio. The performance of the heterogeneous sensing layer (i.e. ZnPc/CuP blend)-based sensor evaluated in term of response and selectivity is different from that of single homogeneous films.
Sensors and Actuators B: Chemical, 2003
The interaction between some ambient reactive compounds and organic or inorganic thin layers can ... more The interaction between some ambient reactive compounds and organic or inorganic thin layers can cause variations in the physical properties of the chemically interactive layers. Molecules in the gas phase, which are adsorbed onto the surface or absorbed in the bulk of the thin layer, generally modify the electrical or optical or mass properties of the gas-sensitive material giving rise to a number of different kinds of chemical sensors based on different working principles. This work reports and discusses the experimental results obtained with optical absorbance measurements in UV-Vis spectral range onto these optical sensitive layers in controlled atmosphere containing vapours. In particular, very interesting results have been obtained by optical absorption measurements carried out in the region of the typical Q band of phthalocyanines and a selectivity toward different vapours, depending both on the metal and the peripheral substituents of the macrocycle, was found. The as-manufactured sensors have been arranged in an array configuration and examples of applications for "electronic optical nose" to the analysis of some volatile organic compounds (VOC) which are of interest in food analysis are reported in this work.
Sensors and Actuators B: Chemical, 2007
Matrix assisted pulsed laser evaporation (MAPLE) is a new promising laser-based technique thought... more Matrix assisted pulsed laser evaporation (MAPLE) is a new promising laser-based technique thought for polymer or biomaterial thin films deposition. In this work, the MAPLE technique has been used for the deposition of titania (TiO2) nanoparticle thin films to be used for gas sensor applications. For this purpose, an aqueous solution of TiO2 nanoparticles, synthesized by a novel chemical route,
Langmuir
The NO2 gas-sensing characteristics of chemiresistors in the form of multilayered Langmuir-Blodge... more The NO2 gas-sensing characteristics of chemiresistors in the form of multilayered Langmuir-Blodgett films of a symmetrically substituted phthalocyanine, containing on the periphery four amidic groups-CONH-, have been studied. Floating layers were spread onto the water surface from a chloroform solution and were transferred onto both hydrophilic and hydrophobic quartz substrates using the vertical lifting method. Response and recovery times have been measured for different working temperatures at a fixed NO2 concentration. Dynamic response characteristics of the electrical conductance of the LB films to different NO2 concentrations, carried out in dry air, have shown a high sensitivity to concentrations of nitrogen dioxide smaller than 20 ppm at room temperature. All measurements have been carried out using coplanar configurations of the devices.
IEEE Sensors Journal, 2003
AbstractWe developed and tested gas sensing devices based on TiO2 nano-crystalline films produce... more AbstractWe developed and tested gas sensing devices based on TiO2 nano-crystalline films produced at room temperature by the novel growth method of cluster beam deposition. The devices show a very good response to ethanol, methanol, and propanol and an overall ...
Applied Surface Science, 2007
The MAPLE technique has been used for the deposition of nanostructured titania (TiO2) nanoparticl... more The MAPLE technique has been used for the deposition of nanostructured titania (TiO2) nanoparticles thin films to be used for gas sensors applications. An aqueous solution of TiO2 nanoparticles, synthesised by a novel chemical route, was frozen at liquid nitrogen temperature and irradiated with a pulsed ArF excimer laser in a vacuum chamber. A uniform distribution of TiO2 nanoparticles with an average size of about 10nm was deposited on Si and interdigitated Al2O3 substrates as demonstrated by high resolution scanning electron microscopy-field emission gun inspection (SEM-FEG). Energy dispersive X-ray (EDX) analysis revealed the presence of only the titanium and oxygen signals and FTIR (Fourier transform infra-red) revealed the TiO2 characteristic composition and bond. A comparison with a spin coated thin film obtained from the same solution of TiO2 nanoparticles is reported. The sensing properties of the films deposited on interdigitated substrates were investigated, too.
ChemInform, 2004
This paper gives an overview about the principles and the technologies used in solid-state gas se... more 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.
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Papers by Simonetta Capone