- Materials Science, Sensors and Sensing, Electrospinning, Mesoporous Silica Modification, Relative Humidity, Physics, and 10 moreChemistry, Nanotechnology, Nanoscience, Renewable Energy, Biotechnology, Environmental Sustainability, Chemical Engineering, Sensors, Sensor Technology, and Nanowires based gas sensorsedit
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ABSTRACT The thermogravimetry technique allows to study desorption and sublimation processes of volatile compounds in different environments. This technique shows a large range of applications for planetary insitu mission, e.g. the... more
ABSTRACT The thermogravimetry technique allows to study desorption and sublimation processes of volatile compounds in different environments. This technique shows a large range of applications for planetary insitu mission, e.g. the measurement of water and organics in a planetary environment. The capability of a thermogravimeter to study water desorption from clay has been verified. Another experiment which can find application in a planetary mission concerns the measurement of enthalpy of sublimation of a particular volatile compound.
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The crystallization of amorphous TiSi2 coevaporated and WSi2.4 chemical vapor deposited thin films was performed by tungsten lamp annealing system at various temperatures and time. A typical annealing process was composed of a fast... more
The crystallization of amorphous TiSi2 coevaporated and WSi2.4 chemical vapor deposited thin films was performed by tungsten lamp annealing system at various temperatures and time. A typical annealing process was composed of a fast heating at a constant rate of ∼83 °C/ s up to the required temperature, followed by a fast cooling step to room temperature. A metastable form of TiSi2 (base‐centered orthorhombic) and of WSi2 (hexagonal) is formed first and the entire amorphous layer is consumed before this phase undergoes a polymorphic transformation to face‐centered‐orthorhombic TiSi2 and to tetragonal WSi2, respectively, at higher temperatures. The temperature of transformations are found well correlated with those measured in furnace annealing processes, with typical heating rates varying from 1 to 50 °C/min, and reported in an Ozawa’s plot (logarithm of the heating rate versus reciprocal of the temperature of transformation) to evaluate the activation energies of the aforesaid transformations. These latte...
Research Interests: Engineering, Materials Science, Crystal Growth, Crystallization, Heat Treatment, and 13 moreChemical Vapor Deposition, Thin Films, Annealing, Thin Film, Physical sciences, Recrystallization, Phase Transformation, X ray diffraction, Tungsten, Auger electron spectroscopy, Electric Conductivity, Vacuum Science and Technology, and Transition Temperature
In this paper the MOVIDA instrument is presented, a micro-thermogravimeter (light, small and low-power consuming) able to perform key in-situ measurements in the Lunar environment (i.e. water and organics amount in the dust, water ice... more
In this paper the MOVIDA instrument is presented, a micro-thermogravimeter (light, small and low-power consuming) able to perform key in-situ measurements in the Lunar environment (i.e. water and organics amount in the dust, water ice detection, charge-to-mass ratio of dust grains). <P /
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In environments polluted by mercury vapors that are potentially harmful to human health, there is a need to perform rapid surveys in order to promptly identify the sources of emission. With this aim, in this work, a low cost, pocket-sized... more
In environments polluted by mercury vapors that are potentially harmful to human health, there is a need to perform rapid surveys in order to promptly identify the sources of emission. With this aim, in this work, a low cost, pocket-sized portable mercury measurement system, with a fast response signal is presented. It consists of a preconcentrator, able to adsorb and subsequently release the mercury vapour detected by a quartz crystal microbalance (QCM) sensor. The preconcentrator is based on an adsorbing layer of titania/gold nanoparticles (TiO2NP/AuNPs), deposited on a micro-heater that acts as mercury thermal desorption. For the detection of the released mercury vapour, gold electrodes QCM (20 MHz) have been used. The experimental results, performed in simulated polluted mercury-vapour environments, showed a detection capability with a prompt response. In particular, frequency shifts (−118 Hz ± 2 Hz and −30 Hz ± 2 Hz) were detected at concentrations of 65 µg/m3 Hg0 and 30 µg/m3 ...
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Abstract Electrospun nanofibrous nets of titania (anatase) were deposited on interdigitated microelectrodes and photocatalytically decorated with gold nanoclusters (AuNCs) upon UV irradiation. The resulting devices appeared to be... more
Abstract Electrospun nanofibrous nets of titania (anatase) were deposited on interdigitated microelectrodes and photocatalytically decorated with gold nanoclusters (AuNCs) upon UV irradiation. The resulting devices appeared to be conductive even at room temperature (Ohmic behavior), and were investigated as potential chemosensors capable of entrapping and detecting elemental mercury vapors in the atmosphere. The strong affinity and specificity of Au for Hg 0 conferred to AuNCs a key role in mercury sensing, by inducing a decrease in current upon mercury adsorption. Sensors conductivity appeared not to be dependent on humidity. The resulting chemosensors are expected to be inexpensive, very stable (due to the peculiar structure), and requiring low power, low maintenance and simple equipment to work.
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In this paper we present the design and fabrication of two flexible sensor devices: humidity sensor and ammonia sensor integrated with electronic circuit interface on thin flexible substrate (8 mum). The transducers layout has been... more
In this paper we present the design and fabrication of two flexible sensor devices: humidity sensor and ammonia sensor integrated with electronic circuit interface on thin flexible substrate (8 mum). The transducers layout has been optimized by means of numerical simulations. A thin layer of Bisbenzocyclobytene (BCB) is used as dielectric sensitive material in humidity sensor. Conversely a mixed polymer
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We present the design and fabrication of a chemoresistive sensor array for the volatile organic compounds and gas detection. Different nanofibrous conductive polymers, produced by electrospinning technique, have been used as chemical... more
We present the design and fabrication of a chemoresistive sensor array for the volatile organic compounds and gas detection. Different nanofibrous conductive polymers, produced by electrospinning technique, have been used as chemical interactive materials. Sensor array was integrated with read-out electronic circuits on flexible substrate. In order to obtain high electrical performances maintaining integration capability, on plastic materials, respect to
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Among various attempts of mimicking olfactory system the present work focuses on the sensorial surface of mammalian olfactory cells. The aim of this research is to develop, in a single step, synthetic fibres mimicking the long, no motile... more
Among various attempts of mimicking olfactory system the present work focuses on the sensorial surface of mammalian olfactory cells. The aim of this research is to develop, in a single step, synthetic fibres mimicking the long, no motile cilia of the olfactory cells. Electrospun conductive nanofibrous layers of doped polyaniline, suitably blended to a group of polymers capable to carry
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Abstract This paper illustrates the experimental performance of a thermopile made by five Cu/Pd thermocouples (junction area 200 × 200 μm) which shows sensitivity to both temperature and hydrogen and has a relatively low Johnson noise.... more
Abstract This paper illustrates the experimental performance of a thermopile made by five Cu/Pd thermocouples (junction area 200 × 200 μm) which shows sensitivity to both temperature and hydrogen and has a relatively low Johnson noise. The thermoelectric power of the elementary thermocouple is a few μV/K. The H 2 responsivity in a H 2 + N 2 flux is found to be dependent on the temperature difference T 2 - T 1 between the two thermocouple junctions and on the H 2 concentration. With T 2 - T 1 equal to 100 K, T 2 equal to 373 K and a H 2 concentration of 88 ppm in N 2 , the thermopile gives a responsivity of about 750 nV/(ppm of H 2 ). Response times depend on the temperature of both junctions and the hydrogen concentration in the H 2 + N 2 mixture and are mainly related to the adsorption-desorption processes of the Pd film itself. Data on the responsivity dependence versus H 2 concentration and versus T 2 - T 1 are given and discussed. Noise problems are finally taken into account in order to consider the noise equivalent H 2 concentration NEC H2 .
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Research Interests: Chemistry, Analytical Chemistry, Biomedical Engineering, Biosensors, Biomimetics, and 15 moreElectrospinning, Nanotechnology, Medicine, Humans, Conducting Polymer, Electronic Nose, Nanostructures, BioSensors, Gases, Elsevier, Equipment Design, Equipment Failure Analysis, Electric Conductivity, Biosensing Techniques, and conductometry
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Abstract The volatile, organic, and salt content of regoliths can be a powerful marker to constrain the taxonomy of asteroids. These compounds are present in different amounts among the various meteorite types. As an example, carbonaceous... more
Abstract The volatile, organic, and salt content of regoliths can be a powerful marker to constrain the taxonomy of asteroids. These compounds are present in different amounts among the various meteorite types. As an example, carbonaceous material span ...
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In this work an attempt to obtain a more compact artificial system for gas sensing, properly designed on a transducer, is presented. This novel device can be applied for a wide application range such as environmental, bio-medical,... more
In this work an attempt to obtain a more compact artificial system for gas sensing, properly designed on a transducer, is presented. This novel device can be applied for a wide application range such as environmental, bio-medical, agriculture etc. fields. In the Nature, a mucous layer covering olfactory receptor cells, selectively tunes chemical interactions among odorous molecules and sensing system. An odor, in fact, is perceived only if it is able to cross mucus of nasal cavity. A proper hydrophobic Teflon-like overcoating tunes chemical interactions, humidity free, between odorous molecules and sensing system, miming mucus covering olfactory receptor cells. Here the latters were represented by doped polyaniline added of polyethylenoxide. The interacting surface has been enormously enhanced creating nanofibrous coatings by electrospinning deposition technique. Such nanofibers can be compared with the olfactory cilia covered by mucus. Few modifications of both overlayers and nanof...
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ABSTRACT Flexible sensors are gaining increasing interest in a number of applications, including biomedical, food control, domotics and robotics, having very light weight, robustness and low cost. In order to improve signal-to-noise... more
ABSTRACT Flexible sensors are gaining increasing interest in a number of applications, including biomedical, food control, domotics and robotics, having very light weight, robustness and low cost. In order to improve signal-to-noise ratio, integration of readout electronics is crucial and several technologies are available for the fabrication of thin film transistors (TFTs) based circuits on flexible substrates. Among these technologies, the low temperature polycrystalline silicon (LTPS) is particularly attractive, since LTPS TFTs show excellent electrical characteristics, good stability and offer the possibility to exploit CMOS architectures. The different aspects for the direct fabrication of LTPS TFTs on polymer substrates are reviewed and the specific fabrication process adopted on ultrathin polyimide substrates is described in some detail. Then, as examples of flexible sensing systems, we present both chemical and physical sensors integrated with LTPS TFTs frontend electronics. The present results can pave the way to advanced flexible sensing systems, where sensors and local signal conditioning circuits can be integrated on the same flexible substrate.
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Abstract The effects of hydrogen absorption and desorption in Pd films are studied through reflectivity and conductance measurements. The data show that there is an appreciable variation in both signals even when the sample is exposed to... more
Abstract The effects of hydrogen absorption and desorption in Pd films are studied through reflectivity and conductance measurements. The data show that there is an appreciable variation in both signals even when the sample is exposed to a low hydrogen concentration that does not induce the αβ transition. The reflectivity variations are explained in terms of a rise of the Fermi level in the bulk of the Pd film, while the conductance decrease in a hydrogen atmosphere is related to the behaviour of scattering centres of the absorbed hydrogen atoms. Such ‘bulk’ effects are correlated to the flat-band voltage shift measured in Pd-gate MOS capacitors and two contributions to this quantity are isolated by a temporal analysis of the processes. A model based on two different sites for the absorbed hydrogen atoms is proposed to explain the results.
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Abstract - Silica meso porous thin-films were prepared using cetyltrimethylammonium bromide surfactant as a template. The films were deposited by dip-coating on Si and alumina substrates and calcined at 250 and 450°C. The films we e... more
Abstract - Silica meso porous thin-films were prepared using cetyltrimethylammonium bromide surfactant as a template. The films were deposited by dip-coating on Si and alumina substrates and calcined at 250 and 450°C. The films we e characterized by x ray diffraction (XRD) ...
Research Interests: Materials Science, Spectroscopy, FTIR spectroscopy, Heat Treatment, Thin Films, and 15 moreSilica, Thin Film, Si, Methanol, Ethanol, Relative Humidity, Room Temperature, Fourier transform infrared spectroscopy, Memory Effect, Humidity, Dip Coating, Fourier transform infrared, Rutherford Backscattering Spectrometry, Cetyltrimethylammonium bromide, and Mesoporous Material
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Chemical interactive materials (CIM), based on poly(methylmethacrylate-co-bis(benzocyclobutene)) P(MMA-co-BCB) and poly(styrene-co-bis(benzocyclobutene)) P(S-co-BCB) nanoparticles, have been prepared through modified emulsion technique.... more
Chemical interactive materials (CIM), based on poly(methylmethacrylate-co-bis(benzocyclobutene)) P(MMA-co-BCB) and poly(styrene-co-bis(benzocyclobutene)) P(S-co-BCB) nanoparticles, have been prepared through modified emulsion technique. Experimental conditions, in particular the co-monomer ratio and reaction time, have been tuned to modulate nanoparticles&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; dimension and optimize their monodispersity. Resistive relative humidity (RH) sensors based on self-assembled copolymeric nanoparticles, cast deposited onto metal interdigitated electrodes (Al, Au, Cr), have been fabricated. The electrical response and the devices&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; stability have been studied in the range 10-90% RH. Applying 1 V to interdigitated electrodes, a variation of four orders of magnitude, from 10(-12) to 10(-8) A, has been observed and a response time of 130 s has been calculated. Response reproducibility and stability have been tested in subsequent cycles of measurements (working times as long as two days and after six months), confirming the stable performance of the CIMs. Copolymeric nanoparticle assembly has also been studied by quartz microbalance (QMB) devices, where phase shift occurred, by varying RH in the range 10-90%. The CIM coated device shows a sensitivity of about 30 Hz/% (at 10-70% RH), that rapidly increases up to about 2000 Hz/% at 90% RH. The results give evidence for versatile applications of P(MMA-co-BCB) and P(S-co-BCB) nanoparticles for sensing applications.
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The sensitivity to relative humidity of a sensor based on I2-doped polyphenylacetylene thin film membranes has been investigated. The sensor geometry allows its application in miniature devices. The response to humidity variations... more
The sensitivity to relative humidity of a sensor based on I2-doped polyphenylacetylene thin film membranes has been investigated. The sensor geometry allows its application in miniature devices. The response to humidity variations (20%–80%) is fast and reproducible for long times (months).The I/V characteristics suggest that ionic type conductivity is prevailing. Current intensity measurements performed on films of different thicknesses show
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An electrochemical resistive-type sensor device, with a mesoporous silica thin film as sensitive membrane, has been developed and characterised. The silica film has been obtained via evaporation-induced self-assembly (EISA) using a... more
An electrochemical resistive-type sensor device, with a mesoporous silica thin film as sensitive membrane, has been developed and characterised. The silica film has been obtained via evaporation-induced self-assembly (EISA) using a tri-block copolymer ( ...
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The humidity-sensing electrical properties of heterocontacts between p-type La2CuO4 and n-type ZnO semiconductors, and of the single oxides, as a comparison, were studied. The heterocontacts was prepared by mechanically pressing sintered... more
The humidity-sensing electrical properties of heterocontacts between p-type La2CuO4 and n-type ZnO semiconductors, and of the single oxides, as a comparison, were studied. The heterocontacts was prepared by mechanically pressing sintered disks of the two oxides. The electrical characterization of the heterocontacts was carried out using dc and ac measurements at various relative humidity (RH) values, in order to evaluate the sensing mechanisms and the electrical properties of these p-n junctions. Their humidity sensitivity was explained in terms of the variation of the barrier height at the p-n junctions, due to the saturation of the original interface states by physisorbed water, which leads to the release of trapped electrons, resulting in an increase in the forward current. The higher the number of interface states, the higher the RH-sensitivity of the heterocontacts. Electrochemical impedance spectroscopy (EIS) measurements showed, at 90% RH, a distribution of capacitances with ...
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Passive sampling systems (PASs) are a low cost strategy to quantify Hg levels in air over both different environmental locations and time periods of few hours to weeks/months. For this reason, novel nanostructured materials have been... more
Passive sampling systems (PASs) are a low cost strategy to quantify Hg levels in air over both different environmental locations and time periods of few hours to weeks/months. For this reason, novel nanostructured materials have been designed and developed. They consist of an adsorbent layer made of titania nanoparticles (TiO2NPs, ≤25 nm diameter) finely decorated with gold nanoparticles. The TiO2NPs functionalization occurred for the photocatalytic properties of titania-anatase when UV-irradiated in an aqueous solution containing HAuCl4. The resulting nanostructured suspension was deposited by drop-casting on a thin quartz slices, dried and then incorporated into a common axial sampler to be investigated as a potential PAS device. The morphological characteristics of the sample were studied by High-Resolution Transmission Electron Microscopy, Atomic Force Microscopy, and Optical Microscopy. UV-Vis spectra showed a blue shift of the membrane when exposed to Hg0 vapors. The adsorbed ...
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Abstract An environmentally friendly conductive sensor to measure gases and volatile organic compounds (VOCs) in moistened environments, has been designed and fabricated. To achieve this goal, a biodegradable electrospun nanofibrous... more
Abstract An environmentally friendly conductive sensor to measure gases and volatile organic compounds (VOCs) in moistened environments, has been designed and fabricated. To achieve this goal, a biodegradable electrospun nanofibrous scaffold based on a polymer blend containing polyaniline and poly-3-hydroxybutirrate (PANi/PHB) has been employed. Several fabrics composed of distinct proportions of the two polymers have been tested. Morphology, electrical parameters and sensing features of the biodegradable nanofibrous layers have been investigated. The nanofibrous layers obtained through electrospinning technology carried out directly on chemoresistors resulted in highly porous membranes and the potentials of such blended scaffolds have been analyzed, focusing the attention on the influence of humidity on the features of the resulting sensors, also in terms of reproducibility and stability of their responses. Sensor responses to ammonia and further two chemical compounds differently interacting with PANi (i.e. triethylamine and acetic acid) have been measured in dry air and at different percentages of relative humidity, in order to assess in possible applications the influence of PHB in the interactions of PANi with the analytes tested. Due to the properties of the electrospun nanofibres used in these chemoresistors, water vapours seemed to hugely improve the chemical interactions with the selected analytes. This effect suggests a potential use of the proposed chemosensors in monitoring also strongly moist environments.