In this work, a novel data analysis method for the exploitation of semiconductor metal-oxide-based detectors in chromatographic systems is presented and evaluated. The method exploits the properties of the detector response in the time domain for increasing the time resolution of chromatograms measured with gas sensors. The performances in terms of sensitivity and response speed of a microfabricated Cr-doped WO3 sensor array have been compared against a state-of-the-art mass spectrometer detector in order to validate the method in a demanding application such as the determination of the content of volatile organic compounds in wines.

Several active and passive flow control systems are studied to improve the performances of fluid machineries and to increase aerodynamic efficiency of propulsion systems. Among all the well-known active flow control devices, the dielectric barrier discharge plasma actuator (PA) is in full expansion and of great interest in the scientific community. A PA modifies the following behaviour of a fluid by providing an electronically controllable disturbance that brings to drag reduction, flow separation control, enhanced mixing, and noise suppression. PA is potentially easy to construct, has no moving parts and has low power requirements. This leads to its possible applications for separation control in low pressure turbine blade and compressor cascade, tip clearance flow control and compressor stability range extension. The present work reports the design and fabrication of cheap Kapton-based flow turbulence capacitive sensors able to be embedded into aircraft wing profiles and airfoil structures for critical turbulence conditions detection and early-detected separated flows control. The embedded system will provide a Kapton-foil based pressure detection and linear/synthetic jet plasma actuators working in feedback, for prevention and active reduction of separated flow for regional aircraft applications.

Wine aroma volatiles of two different typical Apulian wines made by autochthonous grape varieties (i.e. Negroamaro and Primitivo) were extracted by solid phase extraction (SPE) and analyzed using gas chromatography-mass spectrometry (GC-MS) in conjugation with an electronic nose (E-nose). Eighteen compounds were found over their own odour threshold and they were taken into account for further data analysis. Sensor data were analyzed by principal component analysis (PCA) to investigate the discrimination capability of the sensor array. The concentrations of volatile chemical compounds in wines determined by GC-MS have been correlated with electronic nose (E-nose) responses using partial least squares (PLSs) and quadratic response surface regression (RSR) analysis. By means of these regression models, relationships between E-nose responses and wine aroma compounds were established. Quite all of the 18 wine odorant concentration were predicted at a satisfactory extent; RSR technique gave better prediction results compared to PLS. © 2012 Elsevier B.V. All rights reserved.

A dielectric barrier discharge plasma actuator (PA) was designed and manufactured with microscale dimensions using photolithographic process on fibre glass substrate. AC operation under sinusoidal voltage was investigated experimentally by means of electrical characterisation, smoke flow visualisations and particle image velocimetry. The performances of the micro PA were evaluated and compared with the ones of a macro PA found in this literature. The velocity induced by the micro PA was comparable with the macro PA one, but with lower applied voltage, electrical power dissipation and actuator size. This is particularly interesting for potential applications in turbomachinery. © The Institution of Engineering and Technology 2014.

The present research was motivated by the growing interest of the scientific community towards the understanding of basic gas-surface interaction mechanisms in 1D nanostructured metal oxide semiconductors, whose significantly enhanced chemical detection sensitivity is known. In this work, impedance spectroscopy (IS) was used to evaluate how a top-down patterning of the sensitive layer can modulate the electrical properties of a gas sensor based on a fully integrated nanometric array of TiO2 polycrystalline strips. The aim of the study was supported by comparative experimental activity carried out on different thin film gas sensors based on identical TiO2 polycrystalline sensitive thin films. The impedance responses of the investigated devices under dry air (as the reference environment) and ethanol vapors (as the target gas) were fitted by a complex nonlinear least-squares method using LEVM software, in order to find an appropriate equivalent circuit describing the main conduction processes involved in the gas/semiconductor interactions. Two different equivalent circuit models were identified as completely representative of the TiO2 thin film and the TiO2 nanostructure-based gas sensors, respectively. All the circuit parameters were quantified and the related standard deviations were evaluated. The simulated results well approximated the experimental data as indicated by the small mean errors of the fits (in the range of 10(-4)) and the small standard deviations of the circuit parameters. In addition to the substrate capacitance, three different contributions to the overall conduction mechanism were identified for both equivalent circuits: bulk conductivity, intergrain contact and semiconductor-electrode contact, electrically represented by an ideal resistor R-g, a parallel RgbCgb block and a parallel R-c-CPEc combination, respectively. In terms of equivalent circuit modeling, the sensitive layer patterning introduced an additional parameter in parallel connection with the whole circuit block. Such a circuit element (an ideal inductor, L) has an average value of about 125 mu H and exhibits no direct dependence on the analyte gas concentration. Its presence could be due to complex mutual inductance effects occurring both between all the adjacent nanostrips (10 mu m spaced) and between the nanostrips and the n-type-doped silicon substrate underneath the thermal oxide (wire/plate effect), where a two order of magnitude higher magnetic permeability of silicon can give L values comparable with those estimated by the fitting procedure. Slightly modified experimental models confirmed that the theoretical background, regulating thin film devices based on metal oxide semiconductors, is also valid for nanopatterned devices.

Sn02 nanorods were successfully deposited on 3" Si/Si02 wafers by inductively coupled plasma-enhanced chemical vapor deposition (PECVD) and a wafer-level patterning of nanorods layer for miniaturized solid state gas sensor fabrication were performed. Uniform needle-shape Sn02 nanorods in situ grown were obtained under catalyst- and high temperature treatment-free growth condition. These nanorods have an average diameter between 5 and IS nm and a length of 160 to 300 nm. The Sn02-nanords based gas sensors were tested towards NH3 and CH30H and gas sensingtests show remarkable response, showing promising and repeatable results compared with the Sn02 thin films gas sensors.

SnO(2) nanorods were successfully deposited on 3" Si/SiO(2) wafers by inductively coupled plasma-enhanced chemical vapour deposition (PECVD) and a wafer-level patterning of nanorods layer for miniaturized solid state gas sensor fabrication were performed. Uniform needle-shaped SnO(2) nanorods in situ grown were obtained under catalyst- and high temperature treatment-free growth condition. These nanorods have an average diameter between 5 and 15 nm and a length of 160-300 nm. The SnO(2)-nanorods based gas sensors were tested towards NH(3) and CH(3)OH and gas sensing tests show remarkable response, showing promising and repeatable results compared with the SnO(2) thin films gas sensors.

In this work we proposed design, fabrication and functional characterization of a very low cost energy autonomous, maintenance free, flexible and wearable micro thermoelectric generator (mu TEG), finalized to power very low consumption electronics ambient assisted living (AAL) applications. The prototype. integrating an array of 100 thin films thermocouples of Sb(2)Te(3) and Bi(2)Te(3), generates, at 40 degrees C, an open circuit output voltage of 430 mV and an electrical output power up to 32 nW with matched load. In real operation conditions of prototype, which are believed to be very close to a thermal gradient of 15 degrees C. the device generates an open circuit output voltage of about 160 mV, with an electrical output power up to 4.18 nW.In the first part of work, deposition investigation Sb(2)T(e)3 and Bi(2)Te(3) thin films alloys on Kapton HN polyimide foil by RF magnetron co-sputtering technique is discussed. Deposition parameters have been optimized to gain perfect stoichiometric ratio and high thermoelectric power factor: fabricated thermo-generator has been tested at low gradient conditioned to evaluate applications like human skin wearable power generator for ambient assisted living applications.

Breathanalysishasapowerfulpotentialfordiseasediagnosticsandmetabolicstatusmonitoring.Asol-gelSnOz­basedmicromachinedsensorarraywasdevelopedandtestedforpotentialapplicationinbreathanalysis.Asuitablebreathsamplingsystemwasusedtosamplethealveolarairvolumefromtheairvolumeofoneexpiration.Breathtestsonalveolarairsampledbysomevolunteers,i.e.smokersandnonsmokersindividuals,werecarried out.PrincipalComponentAnalysisappliedtogassensorresponsesshowedgoodpropertiesofdiscriminationbetweensmokersandnonsmokersindividuals.

Wireless sensors networks enable the chance to investigate with enhanced freedom physical phenomena, aiming to increase the informative content obtained by sensors measurements. In this work we will focus on a system allowing to experimentally measure pressure profiles obtained from sensor nodes deployed on a NACA0012 aircraft wing model. By exploiting measurements gathered from sensors, allowing to measure pressure fluctuations of ±600Pa with a resolution of 4Pa, together with results obtained by Computational Fluid Dynamics (CFD) models, the system enables extracting flow profile, thus obtaining information on flow separation and stall phenomenon. Wireless measures are delivered with an enhanced version of IEEE802.15.4e, allowing to decrease power consumption by a factor of 7. Packet routing, based on Routing Protocol for Low-Power and Lossy Networks (RPL), has been improved by means of a newly introduced Lifetime and Latency Aggregatable Metric (L2AM) leading to a 18% increased network lifetime.

Dielectric Barrier Discharge (DBD) plasma devices have been designed and manufactured with micro scale dimensions through photolithographic process on fiber glass substrate. AC operation under sinusoidal voltage up to 14 kVpp and carrier frequency up to 2.5 kHz has been investigated experimentally by means of smoke flow visualizations and Particle Image Velocimetry. Velocity profiles, maximum induced velocity and induced body force have been calculated. A comparison between the microactuator and a conventional macroactuator has been performed. It has been demonstrated that the microactuator produces velocities on the order of the macro scale actuator with a significant reduction in inception voltage, size and mass. This leads to a simpler and a less intrusive dispositive.

Breath analysis, an innovative non-invasive diagnostic technique, bears the potential of drastically reducing the costs of medical diagnostics offering a simple alternative to standard blood analysis. Here, a flame spray pyrolysis (FSP) reactor was used for synthesis and direct deposition of nanostructured metal oxide (MOx) films onto microsensor substrates. These sensors were assembled in an array and tested simultaneously for different analytes requiring low power consumption to heat the sensor to the operating target temperature. The sensors had varying responses to the different analytes depending on sensing material (e.g. SnO2, WO3, ZnO), facilitating improvements on the selectivity of specific analytes (e.g. acetone, methanol, isoprene).

We report on the transmission of a terahertz (THz) radiation through prototype structures based on a p-type silicon substrate. In particular, the bare substrate and progressively more complicated multilayer structures were investigated, allowing to address the effect on the transmission of different factors, such as the orientation of interdigitated contacts with respect to the polarized beam, the temperature, and the current flowing through a conductive SnO2 nanorods layer. A suitable experimental set-up was developed for the direct spectral measurement of transmission in the range of 0.75-1.1 THz at room and low temperatures. A simple Drude-Lorentz model was formulated, finding a quantitative agreement with the experimental transmission spectrum of the bare substrate at room temperature. For the multilayer structures, the spectra variations observed with temperature are well accounted by the corresponding change of the mobility of holes in the silicon p-type substrate. The influence of the contact orientation is consistent with that of a polarizing metallic grating. Finally, Joule heating effects are observed in the spectra performed as a function of the current flowing through the SnO2 nanorods layer. The experimental results shown here, together with their theoretical interpretation, provide insights for the development of devices fabricated on conductive substrates aimed to absorb/modulate radiation in the THz range. (C) 2014 AIP Publishing LLC.

The present work highlights the progress in the field of polymeric package reliability engineering for a flexible thermoelectric generator realized by thin-film technology on a Kapton substrate. The effects of different plasma treatments on the mechanical performance at the interface of a poly-(dimethylsiloxane) (PDMS)/Kapton assembly were investigated. To increase the package mechanical stability of the realized wearable power source, the Kapton surface wettability after plasma exposure was investigated by static contact-angle measurements using deionized water and PDMS as test liquids. In fact, the well-known weak adhesion between PDMS and Kapton can lead to a delamination of the package with an unrecoverable damage of the generator. The plasma effect on the adhesion performances was evaluated by the scratch-test method. The best result was obtained by performing a nitrogen plasma treatment at a radio-frequency power of 20 W and a gas flow of 20 sccm, with a measured critical load of 1.45 N, which is 2.6 times greater than the value measured on an untreated Kapton substrate and 1.9 times greater than the one measured using a commercial primer.

Present work proposed design, finite element tools simulation and prototype fabrication of a low cost energy autonomous, maintenance free, flexible and wearable micro thermoelectric generator (mu TEG), finalized to power very low consumption electronics Ambient Assisted Living (AAL) applications. The prototype, integrating an array of 100 thin films thermocouples of Sb2Te3 and Bi2Te3, generates, at 40 degrees C, an open circuit output voltage of 430 mV and an electrical output power up to 32 nW with matched load. In real operation conditions of prototype, which are believed to be very close to a thermal gradient of 15 degrees C, the device generates an open circuit output voltage of about 160 mV, with an electrical output power up to 4.18 nW. In this work we proposed design, thermal simulation and fabrication of a preliminary flexible and wearable micro thermoelectric generator (mu TEG), finalized to power very low consumption electronics for Ambient Assisted Living (AAL) applications. Presented simulations show the performances of different fabrication solution for the PDMS/Kapton packages, considering flat and sloped walls approach for thermal gradient enhancement.

Present work highlights the progress in the field of polymeric package reliability engineering for a flexible thermoelectric generator realized by thin film semiconductor technology on Kapton

ZnO nanocrystals (2.5-4.5 nm) were prepared by a wet chemical method based on alkaline-activated hydrolysis and condensation of zinc acetate solutions. Dropcasting of the nanocrystals onto alumina substrates allowed the fabrication of gas sensing devices, that were tested towards NO2, acetone and methanol and showed promising results. At low working temperature, the ZnO quantum dots based sensors are selective to nitrogen oxide, in fact a good sensitivity is shown at 200 degrees C at low concentration (2 ppm), while at temperature above 350 degrees C, high responses are obtained for acetone and methanol. The results obtained are stimulating for further developing of nano-ZnO based sensor devices.

In this work we present a thermoelectric energy harvesting system consisting of a miniaturized and wearable flexible thermoelectric generator (TEG) and a dedicated ASIC, finalized to efficiently recover and manage energy from heat dispersed into the environment. The proposed TEG was realized on flexible Kapton substrate, which is particularly appreciated for its optimum properties of chemical and physical stability, permeability to atmospheric agents (humidity, oxygen) and thermal conductivity. Contrary to a conventional rigid substrate, like glass or silicon, a flexible one adds to the device lighter weight, increased robustness, freedom of shape, compactness, and low cost. Although the TEG was designed as "electronic garment" for wearable use in Ambient Assisted Living (AAL) applications, the device can be easily adapted to different contexts thanks to its flexibility and design that extend the application range to various sectors, from home automation and structural health monitoring to biotechnology. A Transfer Length Method (TLM) analysis was performed on three different multi-layer contact schemes in order to select the best solution to use for the deposition of both embedded thermometers to monitor the thermocouples junctions temperature and contact pads to electrically test single partitions of the array. A custom designed ASIC, based on step-up principle was coupled to the TEG in order to ensure a 1.2 V output and complete power management solution for wireless sensing and data acquisition. © 2013 IEEE.