Sensors and Microsystems

FOREWORD

CONFERENCE SPONSOR

COMMITTEES

CONTENTS

Aims of this work were the optimization of a protocol for the immobilization of a biological molecule on an inorganic platform, the manufacture of the sensing element of a biosensor and its full characterization. We used the Glucose Oxidase (GOD) as biological molecule to immobilize and Si-based surfaces as inorganic platform. To define and optimize the best protocol, non biological techniques such as Atomic force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS) and Energy Dispersive X-ray (EDX) coupled to Scanning electron Microscopy (SEM), were used. AFM and XPS measurements were employed to study the surface coverage by linker molecule. Finally, EDX measurement allowed us to provide a direct measurement of the enzyme presence into the sample cross section. Through these techniques, normally used in the microelectronic field, we demonstrated that the immobilization protocol allows one to obtain an uniform layer of linker molecule and its effectiveness.

There is no need to point out the geat importance of extra virgin olive oil both as a foodstuff and from the agroindustrial point of view. As for all fats, the proper conservation of the product is essential also for extra virgin olive oil. Stability to self-oxidation, which leads to product rancidification, is thus very important and has been the subject of many studies, also by our group. In the present research, attention was focused on the artificial isothermal rancidification process at 5 different temperatures ranging from 98 to 180°C using a tyrosinase biosensor operating in n-hexane. This made it possible to calculate all the principal kinetic parameters of the process under examination.

The increasing commercial interest in exploiting the therapeutic value of Lactoferrin has stimulated the need for reliable assays for its determination in milk at the endogenous level. In this study we developed and characterized an immunosensor for the determination of antibacterial protein (Lactoferrin), with the aim of suggesting this procedure for routine control of an important foodstuff product such as buffalo milk. At the same time, using also another new electrochemical immunosensor for the measurement of immunoglobulin G, it proved possible to determine also immunoglobulin G in the same buffalo milk samples. Briefly, milk contains several protective proteins, including Lactoferrin and immunoglobulin G, that can contribute to the preservation of milk. In the present paper we successfully studied two new immunosensor devices for the analysis of both of these important proteins.

This work reports on the development of a piezoelectric DNA biosensor for the identification of enhanced Green Fluorescence Protein gene often used as a marker of gene delivery. The oligonucleotide sequence of 20 bases selected from the starting DNA has been immobilized on quartz crystal surface via biotin-streptavidin interaction. The detection of the eGFP gene was examined and optimized and the analytical parameters of the system were studied. The developed sensor was applied to the analysis of samples extracted and amplified by polymerase chain reaction.

The aim of this experimentation was the evaluation of benzo(a)pyrene-DNA adducts (BaP-DNA adducts) formation using graphite screen printed electrodes (SPE) and chronopotentiometry. Graphite electrochemical sensors appeared a useful tool for the realization of a rapid method of analysis for the detection of BaP-DNA adducts. To test the performance of these devices the electrochemical response produced by genomic DNA sequences adsorbed on the electrochemical transducer was characterized. A concentration dependent oxidation peak was observed at +1.050 mV vs Ag/AgCl reference electrode, this peak is due to the guanine oxidation. Moreover the response of the immobilized DNA to BaP, and other polycyclic aromatic hydrocarbons (PAHs), was characterized. Depending on the hydrophobicity of the target molecule either a decrease (>3 aromatic rings) or an increase (≤3 aromatic rings) of the guanine oxidation peak was observed. A combination of UV light and oxidising conditions (0.4 µM H₂O₂) were used to obtain oxygenated species such as diol epoxide. Under these experimental conditions the formation of oxidised BaP ((ox)BaP) derivatives was followed by UV spectra monitoring the appearance of an absorbance maximum at λ =264 nm. The formation of (ox)BaP-DNA adducts was evaluated by chronopotentiometry using screen printed electrodes.

Here we report, for the first time, the use of poly[ferrocene]-1H-pyrrole, a patented polypyrrole derivative synthesized at Technobiochip, to create, using Langmuir-Shaeffer thin film deposition method, an interfacial chemistry on the crystal quartz golden surface to firmly stabilize antibody molecules. Coated quartzes were used to perform a classical antigen-antibody binding reaction on Technobiochip's µLibra 3.1 (Quartz Crystal Microbalance). Our results demonstrate that the antibody binding on coated quartzes was extremely increased (70%) over that shown by bare quartzes. In addition, the antigen-antibody interaction was also significantly improved (30%).

We propose a novel technique to detect DNA hybridization. The technique involves measuring scattered light under surface plasmon resonance (SPR) conditions. We have shown that the maximum scattering angle correlates with the traditionally employed reflection minimum. Measuring of scattered light under SPR conditions has all the functional advantages of the SPR technique. In addition, the proposed technique simplifies device design, increases the dynamic range of analysis, and integrates data with those from surface-plasmon field-enhanced fluorescence spectroscopy. We demonstrate the technique by showing direct registration of 20 bases oligonucleotide hybridization. Also we have investigated the amplification effect of 20nm gold nanoparticles (GNP) on the oligonucleotide immobilization process.

In this work a chemical sensor prototype had been electrochemically characterized using a Single-Walled Carbon Nanotubes (SWCNTs) modified gold microelectrode. Several molecular probes (such as ascorbic acid, uric acid, acetaminophen) were investigated by cyclic voltammetry. These compounds are useful to evaluate the selectivity of the electrochemical biosensor prototypes interesting for several analytical applications in environmental monitoring, food quality control and clinical diagnosis.

The aim of this work was to optimise biomimetic-based strategies for possible pathogen detection. The use of new affinity ligands such as the oligopeptides computationally designed is particularly suitable for large-scale synthesis and overcomes the disadvantages of antibodies or enzymes which are often unstable and expensive. The pathogen prototype system chosen was Listeria bacterium because of the large amount of X ray and NMR structures associated to that pathogen available from the literature. 13 oligopeptides libraries (298 oligopeptides in total) mimicking the binding pocket of the listeria target, the protein cadherin, were designed. The contribution of individual peptide to binding was investigated using Hex a protein-ligand docking program. Four peptides different in length and binding energy were selected for experimental part. High-density colorimetric microarray was used to assess the effective binding and the selectivity of the receptors towards the target. The concentration of pathogen cells in solution ranged from 10⁵ to 10⁹ cells/ml. The raw signals were read using a conventional scanner and elaborated with an image software. The pixel intensity decrease of the signal was interpreted proportional to the probe-target binding. With gasket facilities, cross section data approach was applied detecting up to 512 entities simultaneously. In this way the main analytical parameters were investigated. This study was finalised to gain an understanding of how the parameters calculated by computational modelling could be helpful to select biomimetic receptors to bind the target in experimental conditions.

Here we present a study on the performances of µLibra v3.1, a new and more compact Quartz Crystal Microbalance (QCM) developed at Technobiochip. Using a classical antigen-antibody binding reaction, we tested the potentiality of the instrument (CE₀₆ Certified) to be used as immunosensor valuating accuracy, sensitivity, response linearity and pH buffer effects, respectively. The experiments were performed immobilizing the antibody both on bare and coated quartzes using a self-assembled monolayer (SAM) of 16-mercaptohexadecanoic acid (MHDA). Obtained data demonstrate a good intra-assay accuracy between channels, linearity up to 40 µg/ml (plateau value) and 1 nmol/l as sensitivity. Nevertheless, measured and calculated number of antibody molecules is in agreement indicating a good reliability.

Breath analysis allows monitoring several pathologies in a non invasive way. Notwithstanding semiconductor-based sensors show optimal features for clinical application (easy to manufacture, small in size and cheap) until now specific devices based on MOS sensors for breath analysis are lacking and sensitivity is still poor. In this study are reported preliminary data on the development of an acetone MOS sensor in order to analyze diabetic patient's breath. In₂O₃ nanopowders synthesized by two different sol-gel methods have been compared as sensing layer.

Carbon-based nanostructures are becoming increasingly studied essentially for their possible applications in electronics, optics and biology, such as imaging, sensing and drug delivery. Among the new carbon structures, the single-wall carbon nanotubes (SWNTs) have a prominent position due to their unique functions. Nevertheless, although the size of these new nanoparticles, with their high surface area and unusual surface chemistry and reactivity, poses unique problems for biological material, there is a paucity of information on their toxicological properties to assess potential human health risk…

In this work we present a study about behavior in physiological solution of two kind of nanomaterials, as carbon black and porous silicon. Dissolution of these nanoparticles have been controlled resulting in CB aggregation and PS solubility. These results are useful to evaluated the effects of nanoscale materials into biological system for understanding the human health implications.

The purpose of this study was to test the ability of a QMB based gas sensor array in the analysis of the volatiles present in the headspace surrounding the breast. The goal of the experiment was to use this instrument as support of other diagnostic tools, for an early and non-invasive diagnosis of breast cancer.

The experiment involved a population of 30 women. 14 of them were affected by various forms of breast cancer, 13 were apparently healthy individuals considered as reference. The last three patients were 3 cases whose breast had been replaced by a prosthesis. The measurements were performed by the electronic nose of the University of Rome ‘Tor Vergata’. The results obtained by a multivariate analysis of the data were very encouraging. The electronic nose showed 86% sensitivity, 93% specificity, 14% false negative, 7% false positive. These evidences suggest that the headspace surrounding the breast contains important information about breast healthstate, and the electronic nose is an efficient instrument to reveal and interpret these information.

Air monitoring is a challenging objective both for city safeguard and human health. However, in order to get information on the real population exposure with the necessary spatial and temporal resolution a high density monitoring network would be needed. To this aim, small, reliable, low cost, integrated silicon-based sensors would be required. Among the different materials proposed in literature for gas sensor integration, porous silicon (PS) is one of the most promising because of its intrinsic compatibility with the silicon technology.

In this work, the design and fabrication of a gas sensing chip, containing an array of PS gas sensors integrated along with several electronic basic blocks, by using an industrial CMOS process is reported, along with its electrical characterization. Finally, to demonstrate the functionality of the sensing chip, a simple readout electronic interface connected to one of the sensors is used to implement an integrated current-voltage converter.

A chemical sensor based on Thin-Film Bulk Acoustic Resonator (TFBAR) structure is designed, fabricated and functionally characterized. A novel acoustic gas microsensor is represented by TFBAR consisting of a piezoelectric A1N thin layer sandwiched between two metallic Al electrodes and excited by a microwave signal to build a vibrating membrane integrated onto silicon substrate and resonating at 1.045 GHz frequency. Nanocomposite film based on Single-Walled Carbon Nanotubes (SWCNTs) with nanostructured properties have been prepared by Langmuir-Blodgett (LB) material processing technique to functionalise the surface of TFBAR devices for gas detection. Based on the excellent integration compatibility with SWCNTs-based TFBAR sensor, the studied sensing device provides the potentiality in high-performance gas detection applications. The sensing characteristics towards vapors of acetone, ethylacetate, toluene, alcohols have been measured at room temperature with high sensitivity, fast response, good reversibility and repeatability of response.

In these experiments we evaluated the behavior of water and alcohols rate of evaporation by forced bubbling. Changing the quantity of nitrogen flux into the liquid or the temperature of the measure chamber, a freezer for cold temperatures or an oven for higher ones, it has been possible to analyze and compare the liquid mass evaporation rate with that calculated by Antoine Parameters formula. The results obtained are very similar to the theoretical ones except for Methanol that showed a 15% of higher evaporation rate. A special case is that of Decane, which Antoine Parameters graph presents a lack of values between forty and ninety degrees centigrade. The experiment showed an intermediate behavior between the two set of parameters.

This work is about the development and the optical and electrical characterization of all organic heterojunctions consisting of solution deposited films of poly(3,4ethylendioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS), a few micrometers thick, coated with an ion conducting material. This latter one is a complex obtained by the charge transfer reaction that takes place when acetonitrile solutions of the electron acceptor Tetracyanoquinodimethane (TCNQ) molecules are added to solutions containing the ion conducting sodium-polystyrenesulfonate (NaPSS). The principle of operation on which such devices are based on, relies on the possibility to change optical and charge conducting properties of conjugated polymers by electrically driven oxidization and reduction transitions.

Bare Gold electrodes modified with multi-walled carbon nanotube (MWCNT)/poly(aniline) and MWCNT/poly(pyrrole) composite nanowires were assembled for sensitive and selective detection of nitrites. Several electroanalytical parameters were investigated for the template synthesis of composite nanowires, such as different monomers; different purification and functionalisation procedures of MWCNTs. The morphology of the nanowires was investigated by Atomic Force Microscopy (AFM), and Inverted Optical Microscopy. These new chemical sensors based on nanocomposite materials were fully characterized by Differential Pulse Voltammetry (DPV) working at an applied potential of +900 mV vs. Ag/AgCl. The best analytical performances were observed working at (MWCNT)/poly(aniline) composite nanowire based electrodes, in terms of linear range of concentration (1.00×10⁻⁶−1.00×10⁻³ M), limit of detection (L.O.D. 1.70×10⁻⁶ M), sensitivity (31.85 A mol⁻¹ L cm⁻²), reproducibility (RSD % = 2), response time (8s), and higher selectivity towards common interfence. Finally, this nanostructured sensor prototype was tested in real samples of tap water, to which standard concentrations of nitrite were added, and subsequently evaluating the % of recovery (≥ 90 %). Among the sensors tested, those prepared with poly(aniline)/MWCNT composite nanowires showed the best analytical performances.

The results of investigations of the effects of two organic solvents of preparation, tetrahydrofuran (THF) and 1,1,1,3,3,3 Hexafluoro-2-propanol (HFIP), and of three different electrical geometry of devices on drop-coated poly (methyl-methacrylate)/ carbon black (PMMA/CB) composites gas sensors are presented. Using HFIP solvent, it is possible to obtain a good dispersion of the CB filler in the polymeric matrix but the thermodynamic responses of devices to acetone and ethanol vapours are independent from their morphology and from the geometry of devices. The highest sensor responses are to acetone vapor. This behavior could be probably attributed to the higher chemical affinity of less polar molecule as acetone towards PMMA. The filler dispersions, the current-voltage (I/V) characteristics and the stability of devices in the time were also studied and discussed.

In the frame of a collaboration between the University of Rome “Tor Vergata” (Sensors and Microsystems group) and Centro Sviluppo Materiali SPA, a feasibilty study about the application of a transduction technique based on mass changes for carbon monoxide detection has been carried out. Sensors were developed using TSMR resonators as transduction elements and iron-porphyrins as chemically interactive materials. The results presented in this paper show that the Quartz Micro Balance (QMB) technology is promising for obtaining selective and highly sensitive CO sensors.

Spontaneous deposition of aggregates of a tetraphenylporphyrin derivative, possessing a cationic chiral appended functionality, straightforwardly occurs from aqueous solutions. The thickness of the layers depends on the initial macrocycle concentration. Combined UV-Vis, and CD spectroscopy studies and AFM morphological characterisation reveal that these layered films feature a peculiar fractal-type morphology. This aspect can be of great importance for the construction of solid state chemical sensors featuring interesting stereoselective properties.

Thin porphyrin assemblies, widely used as sensing materials in different kinds of transducers, are usually produced through chemical deposition techniques. In this work novel 5,10,15,20 meso-tetraphenyl porphyrin (Fe(TPP)Cl) films have been deposited by means of a new physical technique named glow discharge induced sublimation (GDS). A preliminary morphological characterization has been performed by means of scanning electron microscopy (SEM): SEM images and highlight the great surface roughness and the high purity of GDS films with respect to films deposited by means of conventionally used procedures (e.g. spin coating (SPIN)) ones. Optical sensing measurements, performed in differently concentrated ethyl alcohol (EtOH) atmospheres, highlight that GDS samples yield higher response intensities than SPIN films, very fast responses and complete recovery.

In this work, structural, morphological, electrical and optical properties of oxide nanowires, employed as active material for gas sensing devices, have been investigated. The reactive metal oxides were deposited by vapour phase condensation process from pure oxide powders on the polished alumina and silicon substrates. For the electrical characterization platinum was deposited as electrodes and a platinum meander was prepared to control the operating temperature. The samples were investigated by electron microscopy techniques.

The sensing performance of the prepared devices has been investigated as a function of temperature and concentration of carbon monoxide and nitrogen dioxide.

Preliminary investigations on humidity sensors based on nanostructured PPA (I₂ doped or pristine) and its copolymer P(PA/HEMA) membranes showed fast and reproducible current intensity variations in the range of relative humidity RH 5–90%. The sensor geometry allows its application in miniature devices and the nanostructure enhances the response to humidity variations with respect to previous studies based on amorphous I₂ doped phenylacetylene. Measurements performed on quartz crystal micro balances have demonstrated that these nano structured polymers can be used also devices able to detect mass variations with a good stability and sensitivity.

Multi-walled carbon nanotubes (MWCNTs) films have been fabricated by using plasma-enhanced chemical vapour deposition (PECVD) system onto Cr-Au patterned alumina substrates, provided with 3 nm thick Fe growth-catalyst, for NO₂ and NH₃ gas sensing applications, at sensor temperature in the range of 100-250°C. Nanoclusters of noble metals surface-catalysts (Au and Pt) have been sputtered on the surface of MWCNTs to enhance the gas sensitivity with respect to unfunctionalised carbon nanotube films. It was found that the gas sensitivity of Pt- and Au-functionalised MWCNTs gas sensors significantly improved by a factor up to an order of magnitude through a spillover effect for NH₃ and NO₂ gas detection, respectively. The NH₃ and NO₂ gas molecules act as electron-donor and electron-acceptor species respectively doping the unfunctionalised and Pt- and Au-modified MWCNTs, which have p-type electrical conductivity in semiconducting character. The gas sensitivity of metal-modified MWCNTs sensors increases with the sensor operating temperature due to better gas adsorption. The metal-functionalised MWCNTs sensors exhibit very high gas sensitivity, fast response, reversibility, good repeatability, sub-ppm range detection limit with the sensing properties of the MWCNTs films tailored by surface-catalyst used to functionalise the MWCNTs sensors.

Resistive oxygen sensors based on strontium titanate powders are promising alternatives to electrochemical zirconia-based automotive λ-sensors. In this work we investigate a series of STFO (SrTi_1−xFe_x)O_3−δ) powders, with x ranging from 0 to 0.6, synthesized by Self-propagating High-temperature Synthesis (SHS). A ball-milling (BM) treatment was subsequently carried out for further structure refinement and grain size reduction. The electrical and high-temperature O₂ sensing properties of the synthesized STFO nanopowders are here reported.

In this work, we will report a brief review about hydrogen sensors based on Pd nanowires and our first approach on fabrication of hydrogen sensor based on array of palladium nanowires. As grown Pd nanowires are broken by an electrical process to modify device resistance. Investigations on treatment's influence are studied using a 4% H₂ mixture in N₂ carrier.

A chemical gas sensor based on a single rope of single walled carbon nanotubes (SWCNTs) has been fabricated first isolating the rope on a silicon/Si₃N₄ substrate and then realizing, at its ends, two platinum microelectrodes by means of a Focused Ion Beam (FIB). Its electrical behaviour at room temperature in toxic gas environments has been investigated and compared to sensors based on bundles of SWCNT ropes. For all the devices upon exposure to NO₂ and NH₃ the conductance has been found to increase or decrease respectively. Response time in NO₂ is however faster for device based on the single rope. A mechanism for molecular sensing is proposed.

In this work, the surprising sensing performances of opto-chemical sensors based on SnO2 particles layers against chemical pollutants either in air and water environment, at room temperature, are reported. The Electrostatic Spray Pyrolysis (ESP) method has been used to deposit the sensing coatings upon the distal end of standard fibers. This technique allows the fabrication of SnO2 layers composed of micron and sub-micron dimensions able to locally modify the profile of the optical near-field collected in the close proximity of the fiber tip. Such layers morphology leads to strong surface interactions between sensing coatings, analyte molecules and the evanescent contribute of the field, resulting in an excellent sensors sensitivity against chemical pollutants, even at room temperature.

Higly oriented pyrolitic graphite (HOPG) electrodes were modified with conductive polypyrrole nanowires obtained by chemical oxidation. Morphological characterizations were carried out and the sensor was investigated analytically for ammonia determination in water. Satisfactory results as linear concentration range (10-200 μM), linear regression equation (y/μA = 2.36 x/μM – 1.36), reproducibility (R.S.D. %= 3 n=3) and limit of detection (LOD=5 μM) were obtained. Finally real drinking water samples were analyzed and the recovery study showed that there was no matrix effect on the sensors performances.

In this study we present a new class of sensors based on polysilsesquioxane-azulene system, that could detect various analytes by changing their conductivity and colour. This system represents one of the first example of guest-host polymer used in the sensor field. Taking advantage of the polysilsesquioxane properties in humid environment and of the brilliant blue azulene, an isomer of naftalene with high dipolar moment, we develop polymeric thin film that could work in high humidity conditions and detect different analytes useful in water analysis in a twofold response in terms of color change and conductivity variation.

In this work, the feasibility to exploit optoelectronic chemo-sensors based on cadmium arachidate (CdA)/single-walled carbon nanotubes (SWCNTs) composites for detection of chemical pollutants both in air and water environments has been investigated. The nanocomposite sensing layers have been transferred upon the distal end of standard optical fibers by the Langmuir-Blodgett (LB) technique. Single wavelength reflectance measurements (λ=1310 nm) have been carried out to monitor chemicals concentration through changes in the optical length of the Fabry-Pérot (FP) cavity induced by the interaction of the sensitive layer with the analyte molecules. The preliminary experimental results evidence the good potentiality of these fiber optic nanosensors to detect toluene and xylene at ppm level both in air and water environments at room temperature.

Sensor arrays based on Quartz Crystal Microbalances (QCM) are widely used in volatile organic compound analysis. These systems typically employ a number of quartzes coated with different chemically interactive materials (CIM). In this work we have studied the possibility of including four different QCM in the same quartz plate and performed preliminary measurements.

Chromatography is an analytical technique whereby a mixture of chemicals may be separated by virtue of their differential affinities for two immiscible phases and this involves traditional analytical instruments of significant size and cost, such as gas chromatograph-mass spectrometer (GC-MS), and therefore on-line, real-time analyses are difficult to realise. In this paper we report on the development of a portable microsystem and the evaluation of innovative micromachined gas sensor array performance for wine quality analysis, monitoring different blend of Apulian wine, looking towards new applications into fast and cheap miniaturized multisensor systems in a more general food quality scenario.

Technobiochip has recently patented a series of poly-pyrrole derivatives. Here we report, for the first time, the development of a low-cost and sensitive colorimetric sensor array for the analysis of different volatile compounds in spirits and liquors using that derivatives. The identification is based on color intensity changes of poly-pyrrole derivatives sensor elements upon ligand binding. The data obtained revealed the sensor's ability for sensitive and specific detection of different type of VOCs, so providing a useful test for foods analysis and environmental monitoring.

In this work we report the functional characterization of a multisensor miniaturised gas chromatographic system prototype for a specific application in food analysis, i.e. for the evaluation of fish freshness. A μ-machined GC column and an array of four micromachined gas sensors based on SnO₂ and In₂O₃ were the basic elements of the prototype. The system was tested to different mixtures of ammonia (NH₃), trimethylammine (TMA) and dimethylammine (DMA), which are volatile species typically used as markers of fish deterioration, showing appreciable properties of gas separation and detection. A specific data analysis method for this application, suitably developed to process the gas sensor chromatograms acquired by the system, allowed the identification and quantification of the components in NH₃/TMA/DMA mixtures.

We developed a novel method to detect the presence of unburned diesel fuel in lubricating oil for internal combustion engine. The method is based on the use of an array of different gas microsensors based on metal oxide thin films. The sensor array, exposed to the volatiles of different engine oil samples contaminated in different percentages by diesel, resulted to be appreciable sensitive to them. Principal Component Analysis (PCA) applied to the sensor response data-set gave a first proof of the sensor array ability to discriminate among the different contaminated oils. Moreover, in order to get information about the headspace composition of the fuel-contaminated engine oils samples, we analyzed the engine oil samples by Static Headspace Solid Phase Micro Extraction/Gas Chromatograph/Mass Spectrometer (SHS-SPME/GC/MS).

In this work, we present the development of a novel wireless e-nose platform designed for indoor distributed VOC detection and quantification. The proposed w-nose, called TinyNose, rely on a small polymeric sensor array that is connected to a commercial wireless mote by means of custom developed electronics. A custom developed software architecture allow for signal acquisition, processing and transmission to a data sink where data are stored and/or presented to the remote user. In this work a preliminary assessment of TinyNose capabilities to operate in open air configuration is conducted by using different source of indoor VOC pollution to be detected and classified by the developed architecture.

We report the use of a new patented polypyrrole derivatives synthesized at Technobiochip for the development of novel series of nano-gravimetric sensors showing a high affinity for many classes of volatile organic and inorganic compounds (VOCs). 20 MHz AT-cut resonant quartzes were coated with the polypyrrole derivatives, applied to the Technobiochip Libra Nose 2.1 and used to distinguish different Italian cheeses. The different types of cheese aromas were evaluated by inspecting the headspace. Finally, we used Principal Component Analysis (PCA) to discriminate samples on the basis of the VOCs released.

In this work we analyze the feasibility of using on-field data to train a sensor fusion subsystem coupled to a gas multisensor device for urban atmospheric pollution measurements. A gas multisensor device has been co-located with a conventional fixed monitoring station in order to collect a suitable training data set for a neural network operating in regression mode. Benzene concentration estimation performance are evaluated by comparing them with conventional station output. Performance relationship with training set length has been also explored showing that 10 days training length is sufficient to obtain a less than 2% error with respect to conventional station measurements for benzene concentration estimation.

In this work we analyze the optimization of tapped delay support vector machines (TDSVMs) for analyzing quantitative e-nose data. Here, an array of nanostructured and polymer based sensors is exposed to several NO2-NH3-RH mixtures in order to built a suitable data set for testing its real time concentration estimation capabilities. TD-SVM performance depends on both SVM and TD lines parameters. The partial knowledge about their mutual relationships and availability of a GRID infrastructure made a brute force approach on performance optimization feasible. Results indicate that while it is not advisable to optimize SVM and TD lines parameters separately, for this problem a region of quasi optimality is detectable for SVM parameters.

The stress in porous silicon during exposition to a liquid is investigated by an approach based on Raman scattering. When the porous silicon structure is exposed to isopropanol or ethanol, a reversible blue shift of the Raman spectra is observed. The blue shift of Raman scattering is ascribed to the contraction induced by the liquids that fill the pores.

A porous silicon based hydrogen filter has been designed in STMicroelectronics R&D centers with the purpose to increase hydrogen permeation in systems where high purity gaseous hydrogen is required.

The use of Pd alloy membranes is quite well established when hydrogen separation from other gases is needed, as, for example, in hydrogen generation systems like electrolysers.

However, such kind of membrane efficiency is very low at room temperature; so a working temperature ranging between 200 and 500°C is requested to obtain proper flow rates. Moreover, the cost of Pd alloy membranes as purifiers is quite high, due to the thickness of the Pd alloy foil able to withstand at high permeation pressure gradients.

In order to improve the performance of a device like that described above, in the STMicroelectronics it has been proposed a new design in which a very thin Pd layer (500 nm) on a porous silicon substrate (200 μm thick) allows to obtain high flow rates using a very small amount of the precious metal (Pd), with no mechanical filter robustness degradation. The thickness of the porous substrate, as well as the design of the polymer sustain, will be evaluated.

RF MEMS switches are currently considered for isolation and transmission of RF signals as the ideal next generation devices with respect to PIN diodes, because of the very low losses, high reliability, no signal distortion and no power consumption. In this work, RF MEMS shunt switches in coplanar waveguide (CPW) configuration have been designed, realized and tested for wideband isolation purposes. SU-8 negative resist technology has been introduced for improving the bridge mechanics and the RF performances of the device. The polymeric material is used to elevate the ground planes of the CPW structure, with minor consequences on the electrical matching and an improvement in the bridge ends definition. The EM design has been followed by a six-step photo-lithographic process on a 4" oxidized high resistivity silicon wafer, up to the release of the bridge by using a plasma etching technique.

This paper presents the experimental results obtained on a digital phase shifter based on RF MEMS coplanar shunt switches for radar, beam forming applications. A new design approach is proposed for the design of digital distributed MEMS phase shifters, and the image parameter representation of two port networks is used to develop an analytic model for this component. Vector Network Analyzer measurements have been performed by recording the scattering (S) parameters of the reflected and transmitted signals, and they have been elaborated to get the signal phase shift around the frequency F = 13.7 GHz used for the design. Actually, good performances of the phase shifter have been obtained with respect to the expected ones.

The accelerometer calibration at low frequencies and low acceleration values requires a specific instrument not easy to find on the market.

To solve this problem a system based on a pendulum has been realized in order to reach frequencies less than 1 Hz and low acceleration values down to 0.01ms⁻².

The system does not require a reference accelerometer, as traditional calibration systems need. The fundamental equation of a physical pendulum is used to obtain the reference acceleration values, which are function only of the angle ϑ (between the gravity direction and the rod).

Nano porous silicon (PS) membranes, obtained by electrochemical etch in fluoridric acid, were used to study the release characteristics of biomolecules through nanochannels. The release of dextrans biomolecules from the nanoporous membranes was deeply affected by material structure parameters, as well as molecular chemistry and concentration.

First results on fabrication of a Transdermal Drug Delivery device are presented. Device consists of two regions with different functions: one used for scrabbling the stratum comeum and injecting the drug and the other one used as drug reservoir. Device is manufactured starting from a silicon substrate where a porous silicon layer is obtained. Silicon substrate permits the integration of our device with a future electronic controller while biodegradable porous silicon is a good choice as drug reservoir. In order to test the device as drug delivery system, L-Ascorbic Acid impregnation has been evaluated by means of FTIR and BET analysis.

Films of CdS and ZnS nanoparticles embedded in a COC polymer matrix were prepared by spin coating cadmium and zinc thiolate precursors dispersed in the polymer solutions. Thermal annealing of the spin coated films at temperatures between 200 and 300°C induces the growth of the nanoparticles in the polymer. The nanoparticle structural and optical properties show a simple dependence on the annealing temperature. This effect can be of interest for sensing and electronic devices based on nanostructured materials.

Two different packaging solutions for integrated thermal gas flow sensors are proposed. The sensors are based on the differential temperature configuration and are made up of two heaters placed between an upstream and a downstream temperature probe. The chip was designed using a commercial CMOS process and thermal insulation of heaters and temperature probes from the substrate was obtained by means of a post-processing technique. The two packaging solutions, corresponding to placing the whole chip inside the flow channel or adapting the pipe to a part of the chip itself, have been compared in terms of device sensitivity increase.

Working a Single cells represents an important type of analysis for the study of the living organism, so new technologies and new methodologies have been developed in these years with this aim. In this work, electrochemical impedance spectroscopy (EIS) measurements are used to detect the presence of a cell above a biochip microelectrode used for single-cell electroporation, thus allowing fully automatic, multisite single cell, electroporation.

The flow cytometer is a useful instrument for a selective, fast and accurate analysis of cells or particles [l]. It is widely used in several application fields ranging from cell biology, medicine, toxicology and environmental monitoring [2]. To this aim, a cell suspension is injected in a laminar flow and hydro-dynamically focused in a single cell flow that is illuminated by a monochromatic light. Scattered or emitted fluorescence light is collected and analyzed providing information for cell classification. In the last years several research groups have been involved in the development of micro flow cytometers. Micro flow cytometers have been demonstrated making use of using plastic (PDMS) or glass materials [3-5]. In this paper we propose the characterization of a novel micro flow cytometer based on silicon integrated hollow core AntiResonant Reflecting Optical Waveguides (ARROWS) [6]. ARROW geometry allows one to use the same channel to guide both the sample stream and the fluorescence excitation light, permitting to rearrange the detection system so as to increase the signal-to-noise ratio. The integrated micro flow cytometer has been characterized by using biological samples marked with standard fluorochromes. The experimental investigation confirms the success of the proposed microdevice in the detection of cells.

In this communication we present the fabrication and characterization of oxidized porous silicon (Psi) micropatterns, obtained by direct laser writing, and chemically functionalized for biological applications. The laser local oxidation technique is a good alternative to the traditional photolithographic process since this approach allows the development of micropatterned biosensors. In fact, from a technological point of view, the standard masking of Psi by means of photoresist presents remarkable difficulties because of the low resistance to the electrochemical process. The micropatterned Psi oxidized surfaces can be properly fnnctionalized by a specific chemical linker. The modified surface is able to link the carboxylic or aminic groups of biological probes. The binding between the functionalized surface and the biological matter has been tested by directly spotting on the Psi local oxide a fluorescent labelled antibody. The device has been characterized by FT-IR measurements and fluorescence macroscopy.

The aim of this work is to explore the prospect to grow carbon nanotubes (CNTs) directly on an interdigitated structure to realize a gas sensor. In order to realize a complete device, we start optimizing CNT growth in a Hot wire chemical vapour deposition (HWCVD) reactor on different Ni-coated substrates, finding best pretreatment conditions, and then varying the total pressure, the substrate temperature and the composition of the gases during CNTs synthesis. The material was morphologically and structurally characterized through scanning electron microscopy and Raman spectroscopy, and for some samples by synchrotron X-ray diffraction. Parallelly, with the view to test sensing properties of the CNTs, a gas sensor, obtained dispersing a CNT solution on gold electrode on glass substrate, was prepared. The device was exposed to different analytes. The results are extremely encouraging and make us really confident on the possibility to realize by direct CNTs growth a sensor in perfect working order.

In this work we present Metal Cladding leaky Waveguides (MCLWs) for chemical and biosensing applications. In particular, we show that MCLW can be used as a basic tool for the realization of liquid, gas and fluorescence sensors. The applications of the device are related to different sensing mechanism, and it is possible to obtain, with a suitable design in according to the application selected, a good sensitivity.

Micro-structured fiber Bragg gratings (MSFBGs) – FBGs in which the cladding layer is locally stripped – exhibit attractive spectral features, exalted by their sensitivity to changes in the optical properties of the external medium. In this work, we propose a novel MSFBGs fabrication technique, based on polymeric coatings and UV laser micromachining, as technological assessment to develop tailorable MSFBGs for specific applications. Finally, the technological improvement in the fabrication process enables the development of MSFBG based photonic devices with multifunction properties.

A new laser scanning flow cytometer system (CLASS) has been here employed for the characterization of real marine one-celled organisms. Our system has been able to measure simultaneously size, refractive index, depolarization and fluorescence of phytoplankton cells, giving both morphological and biological information. Hence, CLASS has proved to be a valuable non-destructive tool for the in-vivo recognition and classification of different microorganisms.

We present an optical probe for the measurement of the turbine inlet temperature (TIT) in gas turbine plants. The probe carries out spectroscopic photometric measurements of the IR radiation emitted in a selected wavelength band by the CO₂ molecules present in the combustion gases. It is mechanically robust and potentially compatible with operating gas turbines. The system has been installed and tested on a full scale combustor test bed.

In this work, Hollow-core Optical Fibers (HOF) functionalized with Single Walled Carbon NanoTubes (SWCNTs) are proposed for volatile organic compounds (VOCs) detection. The sensing probe is composed by a piece of HOF with a termination coated and partially filled by SWCNTs. The infiltration of the SWCNTs inside the HOF holes has been accomplished by means of the Langmuir-Blodgett technique. Far field transmission characteristics have been carried out within the HOF bandwidth. Finally the sensing capability of the proposed sensors has been investigated by exposure in a proper designed test chamber to traces of toluene. The experimental results obtained demonstrate the success of the SWCNTs partial filling within the HOF holes and the sensor capability to perfom VOCs detection with a good sensitivity and fast response times.

We present a novel non intrusive optical system for the on-line characterization of coal fired power plants flue gases. The system carries out both real time particle sizing of solid particles (in the range 0.1 – 10 μm) and concentration measurements of chemical species (as small as few ppm) downstream the electrostatic precipitators. The principle of operation relies on a multi-wavelength extinction technique based on the measurement of the extinction coefficient as a function of the illuminating wavelength.

A portable optical device, for an in-shop integrity assessment of gas turbines ceramic coatings, is described. The main features of the optical scheme are reported together with the description of the miniaturised probe shaped to extend the PLPS detection also at the leading edge. Measurements performed both on specimens aged in laboratory conditions and on operated components are presented and compared with the initial condition. The important meaning of the obtained results is shown with the help of metallographic analyses performed on sections of specimens and components. Finally limits and future perspective of the technique are evidenced.

In this paper, a methodology for the analysis of a resonant cavity enhanced (RCE) photodetector, based on internal photoemission effect and working at 1.55 μm, is reported. In order to quantify the performance of photodetector, quantum efficiency including the image force effect, and its dependence from the inverse voltage applied, are calculated. We propose a comparison among three different Schottky barrier Silicon photodetectors, having as metal layers gold, silver or copper respectively. We obtain that the highest efficiency (0.2%) is obtained with metal having the lowest barrier (Copper). The device fabrication is completely compatible with standard silicon technology.

Non Ionizing Radiation monitoring in wide areas or built environments is a challenging task, as the electromagnetic fields are largely variable over space and time. In this paper we review several NIR sensing instruments and some standard procedures adopted in environmental monitoring activities for the Province of Naples. Moreover we propose electronic and optical sensors which can be massively adopted for fast detection of electromagnetic fields, and a no-perturbation inducing device suitable to locally monitor the telecommunication infrastructures.

Advanced IR emitters and sensors are under development for high detection probability, low false alarm rate and identification capability of toxic gases. One of the most reliable techniques for gas identification is Absorption Spectroscopy, especially in the Mid- and Far Infra-Red, where most molecules exhibit their strongest roto-vibrational absorption bands. A compact non dispersive infrared multi-spectral system is here presented, designed and developed for security and environmental monitoring applications. It utilizes a few square millimeters thermal source, a novel design multipass cell, and a smart architecture micro-bolometric sensor array coupled to a linearly variable spectral filter to perform toxic gases detection and identification. Preliminary tests for sensitivity and selectivity are undergoing using mixtures of ammonia and ethylene. Detection capability down to tens of ppm has been demonstrated. Possible improvements through the implementation of open path and hollow-fiber based sensors are discussed.

Optical fiber sensor technology based on intra-core Bragg Gratings can be used to measure many different parameters including strain, temperature, pressure, displacement etc. In this work the mechanical deformation of a piezoelectric cap is characterized by means a Fiber Bragg Grating (FBG) at frequencies up to 200kHz. We applied to the piezoelectric material a sinusoidal voltage and we calculated the consequent longitudinal cap's deformation. At the resonance frequency of f_RES = 1.5kHz the measured strain ΔL/L is 2.87·10⁻⁴.

Aflatoxin M1 (AFM1) is classified as hazardous food contaminant occurring in several dairy products. A portable and easy-to-handle fluorometer for the AFM1 rapid detection is presented. The system is intended to be used as an “early warning system” so as to quickly single out risk or alarm situations. The addition of cyclodextrin (CD) to the AFM1 solution is investigated, as a tool to enhance the fluorescence signal, in order to increase the system sensitivity. Preliminary results are reported which show that succinyl-β-CD can be successfully used to improve the overall sensitivity.

In this work, magnetic field sensors based on the integration of a Fiber Bragg Grating (FBG) with giant magnetostrictive materials (Terfenol-D rod and Magnetic Shape Memory Alloy, MSMA) are presented. Moreover, the influence of the pre-stress in the magnetic responses have been investigated. This dependence can be exploit to optimize the design of sensor for a successive use in specific application.

Italian extra virgin olive oils bearing labels of certified area of origin were considered. Their multispectral digital signature was measured by means of absorption spectroscopy in the 200-1700 nm spectral range. The instrumentation was a fiber optic-based, cheap, and compact device. The spectral data were processed by means of multivariate analysis and plotted on a 2D classification map. The map showed sharp clusters according to the geographic origin of the oils, thus demonstrating the potentials of UV-VIS-NIR spectroscopy for optical fingerprinting. Then, the spectral data were correlated to the content of the most important fatty acids. The good fitting achieved, demonstrated that the optical fingerprinting can be used also for predicting nutritional and chemical parameters.

This paper presents a preliminary evaluation of the new Multi-Pixel Photon Counter (MPPC) by Hamamatsu Photonics for single-event fast scintillation readout in the nanoseconds range. The MPPC is a segmented high-gain avalanche photodiode realized using cutting-edge semiconductor technology. Each pixel integrates the resistance for avalanche quenching allowing the operation in Geiger-mode at pixel level. Because of the adequate time resolution of the S10361-11 series, LaBr₃, LaCl₃, GSO and YAP Ce-doped fast scintillators were selected for investigating the respective scintillation decays. Single-event voltage signals were analyzed by a LeCroy digital sampling oscilloscope in single-shot mode. Both the MPPC and the oscilloscope are fast enough to perform good sampling of the signal along the exponential decay of light emission.

In this paper, porous silicon layers of different porosity and thickness have been investigated by Raman spectroscopy. The spectral characteristics of the first order Raman scattering (line shape and peak position) were analyzed according to the phonon confinement model in order to estimate the size of the crystallite and evaluate the built-in strain in porous silicon.

Metal-diamond-metal structures were realized and tested under continuous X-ray irradiation. Photocurrent versus applied voltage curves were used to evaluate the mobility-lifetime product of collected charges at different beam intensities. μτ values in the order of 6×10⁻⁶ cm²/V were estimated. As the X-ray source is not monochromatic, Bremsstrahlung contribution was removed and the detector response to Kα copper radiation was evaluated.

The frequency response of integrated thermal gas velocity detectors is estimated by means of 2-Dimensional finite element simulations. The study is devoted to examine the possibility to extend the application field of simple integrated flow meters to the detection of acoustic waves. An original approach for taking into account non negligible heat conduction paths along the third axis is described. The role of the thermal mass of the active elements is highlighted.

Robots operating in harsh and hostile environments need reliable multisensorial systems able to automatically acquire as much information as possible. Sensory data from a range of disparate and independent multiple sensors have to produce an improved model or estimate of the domain of interest. Therefore the automated intelligent combination of data from multiple sensors can derive less ambiguous/uncertain information about the desired state. ENEA, the Italian National Agency for New Technologies, Energy and the Environment, is therefore developing a multisensorial layout for robots operating in hostile environments.

We look at an innovative method for the strain, stress measurement on surface. Our project is a simple imaging technique illuminating a polymer (PDMS) grid, attached on specimen, with a large spectra light source, and recording, with a ccd camera, the grid image obtained by diffracting light. Image acquired under stress is subtracted from one without stress giving a colour map of the surface correlated to the stress intensity. This technique arises from asserted optical techniques. Moreover, taking in account the technological progress (polymer, ccd, LEDs), we make the hardware setup very simple because it doesn't need coherent light source and the detector may be a commercial colour ccd.

In this paper we present an uncalibrated CMOS fully-integrable interface, based on oscillating topology, for wide-range resistive gas sensor applications. The proposed circuit is a low-voltage, low-cost and very simple front-end, able to reveal with good linearity and precision more than six decades of resistance variation and, at the same time, to estimate the sensor parasitic capacitance up to 50 pF. Moreover, the interface has also been designed, at transistor level, in a standard CMOS technology (AMS 0.35μm). In this case, no external resistors or capacitors are required, since passive component values are all integrable. This integrated solution has been developed so to be powered with a low supply voltage (2V) and to have characteristics independent both from supply variations and temperature drifts. This makes the proposed circuit suitable for portable applications. Preliminary experimental results, performed through a discrete element board fabricated with commercial components, have demonstrated the validity of the proposed interface and a good agreement between experimental results and theoretical values.

In this paper we propose a low supply voltage integrated lock-in amplifier, completely designed at transistor level and suitable for those sensor applications where the signal to be measured is buried into noise. The proposed system has been designed for operating with a 77 Hz reference signal and all its blocks have been internally designed, at transistor level and supplied at 2V, in a standard CMOS technology (AMS 0.35μm), so to have a completely integrated solution. Waiting for the chip fabrication, we have also developed and fabricated a lock-in system through a discrete element board with commercial components, for preliminary analysis. It has been proved that the system is able to recover with success signal from noise till to 0.1 S/N ratios without performance degradation: this corresponds to the detection of very small quantities of gas.

In this paper we propose a low-voltage low-power application of a quasi-ideal second generation current conveyor (CCII) as resistive sensor interface. The proposed architecture, which has been implemented using a standard CMOS 0.35μm process, consists of a single block oscillating circuit performing a resistance to period conversion. The same topology could be also used for capacitive sensor interfacing.

The widest deployment of wireless sensors may take advantage from the integration of an antenna realized directly on chip [1], [2].

In this paper a new wireless temperature sensor made with a standard 0.8 μm VLSI process, with an on-chip antenna, is presented. An on-chip antenna allows the elimination of external components, which are usually placed on an additional PCB. As a result, extreme system miniaturization is obtained. On the other hand, system efficiency is degraded by the antenna low Q factor in the practical transmission frequency ranges.

The realised chip includes a 3-stage ring oscillator structure which transforms the silicon substrate temperature variation into a frequency modulation. The signal is transmitted by a small loop antenna structure which is realized by aluminium deposition on the top surface of the chip. The antenna is connected between the input and output pins of the ring oscillator.