PORTABLE DYNAMIC SET-UP WITH DIFFUSION TYPE GAS SOURCE FOR THE CALIBRATION OF GAS SENSORS AND ANALYTIC INSTRUMENTS.
A. Sokolov,** A. Lagutin,** A.Vasiliev,* A. Laptev*
* “PGS-Analytic” (Russia)
** NRC “Kurchatov Institute” (Russia),
Portable dynamic set-up is designed for the calibration of gas sensors and gas analytical instruments “in situ”, that is in the place, where these sensors or instruments are installed (laboratory, factory, ecological monitoring system etc.). The set up uses ambient air for the preparation of calibration gas mixture and is equipped with air pump, catalytic filter removing undesirable impurities from ambient air, and diffusion source of target gas. Using this setup, calibration gas mixture with compounds, which could be liquefied at normal temperature (NH3, NO2, CI2, HCI, formaldehyde, …), are prepared with precision of 1 – 4 %. The set-up powered by rechargeable battery enables the operation during at least 4 hours.
Sensors and Actuators B: Chemical
Volume 173, October 2012, pages 555-561
EFFECT OF CAMELINA OIL OR LIVE YEATS (Saccharomyces cerevisiae) ON RUMINAL METHANE PRODUCTION, RUMEN FERMENTATION, MILK PRODUCTION, AND MILK FATTY ACID COMPOSITION IN LACTING COWAS FED GRASS SILAGE DIETS.
A.R. Bayat,* P. Kairenius,* T. Stefanski,* H. Leskinen,* S. Comtet-Marre,** E. Forano,** F. Chaucheyras-Durand,**, *** K.J. Shingfield*,****
* Animal Production Research, MTT, FI 31600, Jokioinen, Finland
** INRA, Microbiology unit UR454, CR Clermont Ferrand/Theix, 63122 St Genes Champanelle, France
*** Lallemand Animal Nutrition, 19 rue des Briquetiers, BP59, 31702 Blagnac Cedex, France
**** Current address: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, SY23 3EB, United Kingdom
The potential of dietary supplements of two live yeast strains (Saccharomyces cerevisiae; designated as treatment A and B) or camelina oil to lower ruminal methane (CH4) and carbon dioxide (CO2) production and associated effects on intake, rumen fermentation, rumen microbial populations, nutrient digestibility, energy and nitrogen metabolism, milk production, and milk fatty acid (FA) composition of cows fed grass silage-based diets were examined. Four Finnish Ayrshire cows in early-lactation (53 ± 7 DIM) fitted with rumen cannula were used in a 4 × 4 Latin Square with four 42-d periods comprising 23 d of adaptation, 5 d of sample collection, and 14 d of washout. Cows received a control TMR (control treatment) with a 50:50 forage:concentrate ratio (on a DM basis) containing grass silage (Festuca arundinacea) with an in vitro OM digestibility of 686 g/kg DM. Cows on treatments A and B received the control TMR supplemented with one of two live yeasts A or B administered directly in the rumen at 1010 cfu/d. Dietary supplements of 60 g camelina oil/kg diet DM replaced concentrate ingredients in the control TMR (treatment CO). Relative to the control, treatments A and B had no effects on DMI, rumen fermentation and apparent total tract nutrient digestibility coefficients. In contrast, treatment CO lowered DMI and ruminal CH4 and CO2 production, responses associated with non-significant decreases in total tract OM digestibility, in the absence of alterations in rumen fermentation characteristics and the total numbers of rumen bacteria, methanogens, protozoa and fungi. Compared with the control, treatment CO decreased the yields of milk, energy-corrected milk, milk fat, lactose, and protein. Relative to treatment B, treatment CO increased the efficiency of nitrogen utilization due to a lower CP intake. Treatment A had no influence on milk FA composition, while strain B increased cis-9 10:1 and decreased 11-cyclohexyl 11:0 and 24:0 concentrations. Treatment CO decreased milk fat 8:0 to 16:0 and total saturated FA and increased 18:0, 18:1, 18:2, conjugated linoleic acid, 18:3n-3, and trans FA concentrations. Decreases in ruminal CH4 production to treatment CO were related, at least in part to lowered DMI, with no differences between treatment CO and other treatments in ruminal CH4 emission intensity (g/kg of DMI, digestible OM or NDF, g/kg of milk or as a percentage of gross energy intake). Results indicated that live yeasts studied in this experiment had no influence on milk yield, rumen fermentation, apparent total tract digestibility, ruminal CH4 and CO2 production or energy and nitrogen utilization in cows fed diets based on grass silage. Dietary inclusion of 60 g camelina oil /kg diet DM decreased ruminal CH4 and CO2 production in lactating cows, but animal performance was compromised due to lower feed intake.
INFLUENCE OF DIETARY LIPID SUPPLEMENTS ON METHANOGENESIS, DIGESTION AND MILK PRODUCTION IN DIARY COWS.
A.R. Bayat*, H. Leskinen*, I. Tapio**, J. Vilkki**, K.J. Shingfield*
*Animal Production Research FI-31600 Jokioinen, Finland
**Animal Genomics, MTT Agrifood Research Finland
Five Finnish Ayrshire cows in early lactation fitted with rumen cannulae were used in a 5×5 Latin Square with 28 d experimental periods. Treatments comprised a control diet, or the same diet supplemented with 50 g/kg diet DM of myristic acid (MA), rapeseed (RO), safflower (SO) or linseed (LO) oils. Diets were based on grass silage (0.60 diet DM), barley and rapeseed meal. Samples of rumen fluid (n=8) were collected during d 23 of each period. Enteric methane (CH4) production was determined using the SF6 (Sulphur Hexafluoride) technique from d 16 to 21. Data were analyzed using a model that included the fixed effects of period and treatment and random effect of cow. Compared with the control, all lipid supplements lowered DM intake (P<0.01), with MA causing the largest decrease (21.8, 15.0, 19.1, 20.4 and 20.1 kg/d for control, MA, RO, SO and LO, respectively). Yields of milk (28.7, 22.1, 29.0, 29.6 and 28.6 kg/d for control, MA, RO, SO and LO, respectively), energy corrected milk, protein and lactose were lower (P<0.01) for MA compared with other treatments. Lipid supplements had no influence on rumen fermentation, other than an increase (P<0.01) in ammonia-N concentration on MA compared with other treatments. Daily enteric CH4 production was lowest (P<0.01) for MA and highest on the control (614, 403, 475, 488 and 484 g/d for control, MA, RO, SO and LO, respectively). All lipid supplements decreased (P<0.01) g CH4 production/kg energy corrected milk (22.7, 18.8, 17.5, 17.5 and 17.5 for control, MA, RO, SO and LO, respectively), but did not affect (P>0.05) CH4 production per unit of total organic matter digested. Treatments had no influence (P>0.05) on organic matter or fibre digestion. Dietary supplements of plant oils can be used to lower enteric CH4 production of dairy cows, without compromising milk production or diet digestibility. Even though MA lowered CH4 production, the decrease was accompanied by adverse effects on intake and animal performance.
14 th International Meeting on Chemical Sensors – IMCS 2012
2012-05-20 – 2012-05-23
Nürnberg / Nuremberg, Germany Pages 1195 – 1198
ELETRONIC NOSES CALIBRATION PROCEDURE IN THE CONTEXT OF A MULTICENTRE MEDICAL STUDY.
M. Santonico*, G. Pennazza**, R. Capuano***, C. Falconi*, T.J. Vink****, H.H. Knobel****,
M.P. Van der Schee*****, P.J. Sterk*****, P. Montuschic, A. D’Amico*
* Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy
** Center for Integrated Research – CIR, Unit of Electronics for Sensor Systems, Università Campus Bio-Medico di Roma, Via Alvaro del Portillo 21, 00128 Rome, Italy
*** Department of Pharmacology, Faculty of Medicine, Catholic University of the Sacred Heart, Rome, Italy
**** Philips Research Laboratories, Eindhoven, The Netherlands
***** Department of Respiratory Medicine, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
An overview of the scientific literature in the medical field tells us that a large part of electronic nose applications is devoted to breath analysis. A network based study can help testing the validity of this strategy when using many different devices based on identical or different technologies, in view of a use in real clinical practice.
The first step is the instrument calibration using a set of key-compounds. In this work a gas sensor array based on quartz microbalance transducers functionalized with metalloporphyrins (ROTV e-nose), and a Cyranose is used simultaneously in a calibration experiment with three ad hoc selected compounds: ethanol, hexane and ethyl acetate, at concentration levels around 1 ppm. These tests have demonstrated that limits of detection down to tens of ppb are possible. Moreover, a mapping between the two instruments has been performed through the calculation of a model based on Cyranose data, and applied to the ROTV e-nose data, for the prediction of compound concentrations. This test has shown a good ability in concentrations prediction, with an error lower than 10 ppb.
In conclusion, this study provides the first step toward quality assurance of e-nose data in the medical setting.
Sensors and Actuators B: Chemical
Volume 163, Issue 1, 1 March 2012, pages 61-68
HIGHLY SENSITIVE AMMONIA RESITIVE SENSOR BASED ON ELECTROSPUN V2O5 FIBERS.
V. Modafferi*, G. Panzera*, A. Donato*, P.L. Antonucci*, C. Cannilla**, N. Donato***, D. Spadaro****,
* Department of Mechanics and Materials, University of Reggio Calabria, Loc. Feo di Vito, 89100 Reggio Calabria, Italy
** CNR-ITAE “Nicola Giordano”, Salita S. Lucia sopra Contesse 5, 98126 Messina, Italy
*** Department of Matter Physics and Electronics Engineering, University of Messina, Salita Sperone 31, 98166 Messina, Italy
****Department of Industrial Chemistry and Materials Engineering, University of Messina, Salita Sperone 31, 98166 Messina, Italy
A simple sol–gel based electrospinning method has been applied for the synthesis of vanadium oxide/polyvinyl acetate (V2O5/PVAC) fibers for gas sensing applications. The pure phase V2O5 has been subsequently obtained by removing the polymer phase via annealing of the composite fibers in air. The as-spun V2O5/PVAC composite fibers and related products of annealing have been widely studied to characterize their morphological and microstructural properties by TG-DSC, XRD, DRIFT and SEM investigations.
The application of the produced V2O5 fibers as high performance ammonia resistive sensors has been demonstrated. Reversible electrical changes have been observed by exposing V2O5 fibers deposited on interdigited electrodes to sub-ppm concentrations of ammonia gas. The fabricated V2O5 sensor has shown the highest response to ammonia gas at 200–250 °C, with a response and recovery time of about 50 and 350 s, respectively. A linear dependence of the response value on the ammonia concentration has been observed in the range of 0.85–8.5 ppm, with an estimated lower detection limit of about 100 ppb.
Sensors and Actuators B: Chemical
Volume 157, Issue 2, 20 October 2011, pages 473-481
LOW TEMPERATURE GAS SENSING APPLICATIONS USING COPIER GRADE TRASPARENCY SHEETS AS SUBSTRATES.
G. Scandurra*, A. Arena*, C. Ciofi* A. Gambadoro*, F. Barreca**, G. Saitta*, G. Neri***
*Dipartimento di Fisica della Materia e Ingegneria Elettronica, Università di Messina, Italy
** Advanced and Nano Materials Research s.r.l., Viale F. Stagno d’Alcontres, 31, 98166 Messina, Italy
*** Dipartimento di Chimica Industriale e Ingegneria dei Materiali, Università di Messina, Italy
Transparency sheets, coated with copper on both sides by means of thermal evaporation in vacuum, are patterned by direct chemical etching to realize sensing platforms having copper heaters on the backside, and resistances having calibrated temperature coefficient on the topside. The mechanical and thermal stability of these structures was demonstrated up to 70 °C. Bending tests also show that the metallic patterns do maintain unaltered performances after more than 104 bending cycles. Resistance measurements show that the resistance on the patterned copper structures linearly increases with the temperature in the range between room temperature and 70 °C, while above this temperature an irreversible damage occurs. Experimental investigations demonstrate that the heaters on the backside of the sensing platforms allow to obtain a quite uniform temperature distribution on the top side over an area larger than 1 cm2.
Coating the flexible sensing platform by doped polyaniline and carbon nanotubes embedded in a polymer host, a chemoresistive system operating at low temperature is developed, which allows to perform tests at constant temperature, with the temperature being set and monitored by using the heater and the patterned resistance, respectively. The sensing performances of the films are evaluated by means of electrical measurements performed while exposing the samples to different relative humidity levels, and to calibrate ammonia pulses.
Journal of Nanoparticle Research
Volume 13, Number 8, 3327-3334, DOI: 10.1007/s11051-011-0246-x
MICROWAVE-ASSISTED SYNTHESIS, CHARACTERIZATION AND AMMONIA SENSING PROPERTIES OF POLYMER-CAPPED STAR-SHAPED ZINC OXIDE NANOSTRUCTURES.
T. Krishnakumar & Nanotechnology Laboratory,* R. Jayaprakash,** D. Sathya,** N. Pinna,*** V. N. Singh & Thin Film Laboratory,**** A. R. Phani,***** G. Neri******
* Department of Physics, VMKV Engineering College, Vinayaka Mission University, Salem, Tamilnadu 636 308, India e-mail: email@example.com
** Raj Nanotechnology Laboratory, Department of Physics, Sri Ramakrishna Mission Vidyalaya College of Arts
and Science, Coimbatore, Tamilnadu 641 020, India
***Department of Chemistry, CICECO, University of Aveiro, 3810-193 Aveiro, Portugal
****Department of Physics, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India
*****Nano-RAM Technologies, Vijayanagar, Bangalore 560040, India
******Department of Industrial Chemistry and Materials Engineering, University of Messina, 98166 Messina, Italy
Zinc oxide nanostructures were prepared by microwave-irradiation technique in the presence of polyvinyl pyrrolidone as a shape modifier. The synthesized nanostructures were analyzed using scanning and transmission electron microscopy, selected-area electron diffraction, X-ray diffraction, and Fourier transform infrared spectroscopy (FT-IR).
Characterization techniques revealed the formation of crystalline ZnO with a star-like shaped morphology, having the crystal structure of wurtzite. The microwave irradiated samples were further investigated to exploit their electrical and sensing properties. The good sensitivity and relatively short response and recovery times of chemoresistive sensors based on star-like ZnO thick Films in the monitoring of low concentration of ammonia gas in air were related to the peculiar nanostructure of the sensing layer.
Sensors and Actuators B: Chemical
In Press, Corrected Proof – Note to
CARBON NANOTUBES MODIFIED WITH PORPHYRIN UNITS FOR GASEOUS PHASE CHEMICAL SENSING.
L. Lvova,*&** M. Mastroianni,* G. Pomarico,* M. Santonico, *** G. Pennazza,**** C. Di Natale, *** R. Paolesse,* A. D’Amico***
* Department of Chemical Science and Technologies, University Tor Vergata, Rome, Italy
** Faculty of Biology and Soil Science, Saint-Petersburg University, St. Petersburg, Russia
***Department of Electronic Engineering, University Tor Vergata, Rome, Italy
**** University Campus Biomedico, Rome, Italy
In the present work the single wall carbon nanotubes (SWCNTs) were modified with porphyrin units and applied as sensing materials in quartz microbalance (QMB) sensors with an integrated preconcentration unit. Two strategies have been adopted for CNT–porphyrin composites formulation. In the first approach the electropolymerization of pyrrole or pyrrole-substituted porphyrin monomers occurred via formation of conjugated positively charged polypyrrole (PPy) backbone, while negatively charged carbon nanotubes functionalized with carboxylic groups (SWCNT-COOH) acted as a polymer dopant. In the second case the SWCNT–porphyrin composites were chemically synthesized via the interaction between glycyl-substituted porphyrin and non-modified CNTs and then entrapped in PPy/SWCNT-COOH film. The application of CNT–porphyrin composite, both as the preconcentrator adsorbing phase and QMB coating, permitted a substantial sensitivity improvement as far as the possibility to measure volatile organic compounds, such as 1-butanol, in concentrations close to the odor threshold.
Sensors and Actuators B: Chemical
Volume 146, Issue 2, 29 April 2010, Pages 539-544
Selected Papers from the 13th International Symposium on Olfaction and Electronic Nose – ISOEN 2009
ANALYSIS OF THE DYNAMIC FEATURES OF METAL OXIDE SENSORS IN RESPONSE TO SPME FIBER GAS RELEASE.
A. Šetkus,* A. Olekas,* D. Senuliene,* M. Falasconi,** M. Pardo,** G. Sberveglieri**
* Sensors Laboratory, Semiconductor Physics Institute, A. Goštauto 11, Vilnius LT01108, Lithuania
** SENSOR Laboratory, CNR-INFM & University of Brescia, Via Valotti 9, 25133 Brescia, Italy
In this study a metal oxide sensor array is exposed to a time-dependent amount of gas inside the sensor chamber of negligible “dead” volume. Special parameters of the response kinetics are used for multi-parametric featuring of volatile organic compounds (VOCs). The composition of the atmosphere in the chamber varies due to the time-dependent release of the VOCs from a solid phase micro-extraction (SPME) fiber into the flow of synthetic air. Four types of volatile compounds, namely acetone, acetic acid, acetaldehyde and butyric acid, that are known being frequently emitted from infected wounds, are tested in this study. The explorative data analysis (EDA) of the features is performed for the sensor outputs obtained at different carrying gas flow rates and the VOC amounts. Influence of specific aspects of the SPME based sampling on the sensor outputs is estimated. It is demonstrated by the PCA results that the target compounds cannot be distinguished below 3–4 ppm if only the sensor outputs based on the signal magnitudes are used for the featuring of VOCs (static-compatible features). The dynamic features add significant information and allow a better discrimination of the volatile compounds. The classification of the target volatile compounds can additionally be improved by precise control of the VOCs expansion in the chamber in the dynamic exposure approach.
Sensors and Actuators B: Chemical
Volume 145, Issue 1, 4 March 2010, Pages 488-494
FLEXIBLE ETHANOL SENSORS ON GLOSSY PAPER SUBSTRATES OPERATING AT ROOM TEMPERATURE.
A. Arena,* N. Donato,* G. Saitta,* A. Bonavita,** G. Rizzo,** G. Neri**
*Dept. of Matter Physics and Electronic Engineering, Univ. of Messina, Salita Sperone 31, I-98166 Messina, Italy
** Dept. of Industrial Chemistry and Materials Engineering, Univ. of Messina, 98166 Messina, Italy
Flexible sensors for the detection of ethanol at room temperature have been developed by depositing sensitive layers consisting of ITO nanopowder dispersed into poly-diallyldimethylammonium chloride (PDDAC), on the top of interdigitated electrodes based on conductive carbon nanotubes, previously printed onto flexible glossy paper substrates. The morphology and the microstructure of the interdigitated electrodes together with organic–inorganic sensing layer have been investigated by means of SEM, XRD and FT-IR. The electrical behaviour of the developed sensors at room temperature in response to low ethanol concentrations has been discussed as object of our research. The good ethanol sensing properties exhibited at room temperature by the composite film was supposed to originate from the electrostatic interaction occurring between the positively charged PDDAC polyelectrolyte and negatively charged ITO particles.
Vol.6, 1–6, 2008
TUNGSTEN OXIDE NANOWIRES-BASED AMMONIA GAS SENSORS.
G. Neri,* G. Micali,* A. Bonavita,** S. Ipsale,* G. Rizzo,* M. Niederberger,*** N. Pinna****
* Department of Industrial Chemistry and Materials Engineering, University of Messina,
Contrada di Dio, Vill. S. Agata, 98166 Messina, Italy
** Department of Chemical Science and Technology, University of Rome “Tor Vergata,”
Via della Ricerca Scienti?ca 1, 00133 Rome, Italy
***Laboratory for Multifunctional Materials, Department of Materials, ETH Zürich,
Wolfgang-Pauli-Strasse 10, CH-8093 Zürich, Switzerland
****Department of Chemistry, CICECO, University of Aveiro, 3810-193 Aveiro, Portugal
The application of tungsten oxide nanowires synthesized by a simple soft-chemistry route in the presence of deferoxamine mesylate (DFOM) for ammonia gas sensing is reported. The crystalline tungsten oxide nanowires are self-assembled into bundles with typical lengths of 200 to 1000 nm and width around 20 nm. For sensing tests, tungsten oxide nanowires suspended in water were deposited onto alumina substrates by drop-coating and subsequently calcined at 500 °C in air. The sensors were tested at different temperatures to evaluate the best working conditions for ammonia gas monitoring (1–10 ppm) in terms of sensitivity, selectivity and response time. These sensors have proven to detect ammonia gas with remarkably higher sensitivity than other sensors based on tungsten oxides. The response and recovery times are fast (in the order of 2min). All in all, these features make these sensors promising candidates for healthcare applications.
Sensors and Actuators B 130 (2008) 100–104
BREAD BAKING AROMAS DETECTION BY LOW-COST ELECTRONIC NOSE.
A. Ponzoni,* A. Depari,* M. Falasconi,* E. Comini,* A. Flammini,** D. Marioli,** A. Taroni,** G. Sberveglieri*
* CNR-INFM Sensor Laboratory, and University of Brescia, Department of Chemistry and Physics, Via Valotti 9, 25133 Brescia, Italy
** University of Brescia, Department of Electronics for Automation and INFM, Via Branze 38, 25123 Brescia, Italy
In this work we propose a low-cost electronic nose based on a resistance to period converter readout system, suitable to handle a wide range of resistance values (from k? up to tens of G?) with high accuracy (<1%). An array composed of four metal oxide based gas sensors, with baseline resistance spreading on the above range has been used to validate the system. The electronic nose has been applied to the detection of key aromas peculiar of different stages of the bread baking process has been chosen as target application, revealing the suitability of the proposed electronic nose to distinguish these volatiles in an ordered manner re?ecting the different baking step they represent.
Sensors and Actuators B 131 (2008) 5–9
Copyright © 2008 Elsevier B.V. All rights reserved.
DEVELOPMENT OF CONDUCTING POLYMER SENSOR ARRAYS FOR WOUND MONITORING.
A. Bailey,* A.M. Pisanelli,* K.C. Persaud*
*School of Chemical Engineering and Analytical Science, Faraday Building, The University of Manchester, PO Box 88, Sackville Street, Manchester M60 1QD, UK
A study of conducting polymer sensors for use in monitoring the headspace of metabolites produced from superficial wounds and burns is in progress. Gas chromatography–mass spectrometry (GC–MS) headspace analysis of the most common bacterial species found to be present in wounds has been achieved to determine the key volatile markers for sensor detection.
A preliminary study of sensor arrays using seven pure volatiles known to be produced from the bacteria studied is reported [R.A. Allardyce, V.S. Langford, A.L. Hill, D.R. Murdoch, Detection of volatile metabolites produced by bacterial growth in blood culture media by selected ion how tube mass spectrometry (SIFT-MS), J. Microbiol. Methods 65 (2) (2006) 361–365; R.J. Wiggins, M. Wilks, S. Tabaqchali, Analysis by gas liquid chromatography of production of volatile fatty acids by anaerobic bacteria growth on solid medium, J. Clin. Pathol. 38 (1985) 933–936]. The sensors used were based on an existing sensor array, previously used in a smart are detection system [E. Scorsone, A.M. Pisanelli, K.C. Persaud, Development of an electronic nose for detection, Sens. Actuators B: Chem. 116 (2006) 55–61], and a sensor array developed from the same design and conguration has given stable results, especially towards butyric acid and ethanol.
CARBONYL SULPHIDE (COS) MONITORING ON MOS SENSORS FOR BIOMEDICAL APLLICATIONS.
G. Neri,* A. Bonavita,** S. Ipsale,* G. Micali,* G. Rizzo,* N. Donato***
* Dept. of Industrial Chemistry and Materials Engineering, University of Messina, C/da di Dio,
Vill. S. Agata, 98166 Messina, Italy, *e-mail – firstname.lastname@example.org
** Dept. of Chemical Science and Technologies, University of Rome “Tor Vergata”
00133 Rome, Italy
*** Dept. of Matter Physics and Advanced Physical Technologies, University of Messina, Italy
Resistive metal-oxide semiconductor (MOS) sensors have been tested in the monitoring of carbonyl sulphide (COS), a biomarker for acute rejection (AR) in lung transplanted patients. COS concentration in the breath of these patients (about 0.5 ppm) is in fact more higher than that found in healthy peoples, making possible the real time diagnosis of this pathology by breath analysis. In2O3-based MOS resistive sensors have been therefore tested at different temperatures and COS concentrations in order to optimize the sensor response and response/recovery time. The ultimate aim of this work is to develop a simple and cost-effective breath test for the acute rejection in lung transplanted patients.
ISIE 2007 – IEEE International Symposium on Industrial Electronics, June 4-7, 2007, Vigo, Spain.
WO3 NANOWIRE-BASED AMMONIA GAS SENSORS FOR BREATH ANALYSIS IN HEALTHCARE APPLICATIONS.
G. Neri, G. Micali, A. Bonavita, S. Ipsale, G. Rizzo, M. Niederberger, N. Pinna
Breath analysis of ammonia gas by means of MOS sensors has promising applications in healthcare, allowing for example the easy diagnosis of uremia or determination of dialysis time. This is possible because of the correlation between exhaled ammonia and nitrogen compounds (i.e. urea and creatinine) in the blood. However, ammonia concentrations to be detected are in the range 100 ppb-2 ppm and highly sensitive and selective sensors are needed. Here we report on the application of WO3 nanofibers for reversible ammonia gas sensing. Nanotubes/fibers can contribute to the development of novel gas sensors from these materials with high performances as consequence of their high surface-to-volume ratio. We report a simple soft-chemistry route to crystalline tungsten oxide nanowires self-assembled into bundles, starting from tungsten isopropoxide in benzyl alcohol to provide a versatile reaction system for the nonaqueous preparation of these nanowires. Nanowires obtained are crystalline with a length ranging typically from 300 to 1000 nm and width between 20 and 100 nm. For the gas-sensing tests, a suspension of the tungsten oxide nanowires in ethanol was deposited onto alumina substrates by drop-coating and subsequently calcined at 500 °C in air. The sensors were tested at different temperature to evaluate the best working conditions for ammonia gas monitoring (1-10 ppm) in term of sensitivity, stability and response time. WO3-nanofiber-based sensors have proven capable of detecting ammonia gas with high sensitivity, remarkably higher than that obtained on previous sensors based on bulk WO3 materials. The response time is rapid (a few seconds) and the recovery time is also fast (in the order of 2–3 min), making the sensor promising candidate for healthcare applications.
E-MRS 2007 Spring Meeting will be held in Strasbourg (France), from May 28 to June 1, 2007
DETERMINATION OF HYDROGEN SULFIDE AND VOLATILE THIOLS IN AIR SAMPLES BY MERCURY PROBE DERIVATIZATION COUPLED WITH LIQUID CHROMATOGRAPHY-ATOMIC FLUORESCENCE SPECTROMETRY.
E. Bramanti,* L.D’Ulivo,* C.Lomonte,** M.Onor,* R.Zamboni,*** G.Raspi,* A. D’Ulivo*
* Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa, Italy
** Ambiente s.c.r.l., Via Frassina 21, 54033, Carrrara, Massa, Italy
*** Department of Chemistry and Industrial Chemistry, University of Pisa, Via Risorgimento 35, 56126 Pisa, Italy
A new procedure is proposed for the sampling and storage of hydrogen sulphide (H2S) and volatile thiols (methanethiol or methyl mercaptan, ethanethiol and propanethiol) for their determination by liquid chromatography. The sampling procedure is based on the trapping/pre-concentration of the analytes in alkaline aqueous solution containing an organic mercurial probep-hydroxymercurybenzoate, HO–Hg–C6H4–COO− (PHMB), where they are derivatized to stable PHMB complexes based on mercury–sulfur covalent bonds. PHMB complexes are separated on a C18 reverse phase column, allowing their determination by liquid chromatography coupled with sequential non-selective UV–vis (DAD) and mercury specific (chemical vapor generation atomic fluorescence spectrometry, CVGAFS) on-line detectors. PHMB complexes, S(PHMB)2CH3S-PHMB, C2H5S-PHMB and C3H7S-PHMB, are stable alt least for 12 h at room temperature and for 3 months if stored frozen (−20 °C).
The best analytical figures of merits in the optimized conditions were obtained by CVGAFS detection, with detection limits (LODc) of 9.7 μg L−1 for H2S, 13.7 μg L−1 for CH3SH, 17.7 μg L−1 for C2H5SH and 21.7 μg L−1 for C3H7SH in the trapping solution in form of RS-PHMB complexes, the relative standard deviation (R.S.D.) ranging between 1.0 and 1.5%, and a linear dynamic range (LDR) between 10 and 9700 μg L−1. Conventional UV absorbance detectors tuned at 254 nm can be employed as well with comparable R.S.D. and LDR, but with LODc one order of magnitude higher than AFS detector and lower specificity. The sampling procedure followed by LC–DAD-CVGAFS analysis has been validated, as example, for H2S determination by a certified gas permeation tube as a source of 3.071 ± 0.154 μg min−1 of H2S, giving a recovery of 99.8 ± 7% and it has been applied to the determination of sulfur compounds in real gas samples (biogas and the air of a plant for fractional distillation of crude oil).
Analytica Chimica Acta
Volume 579, Issue 1, 2 October 2006, Pages 38-46
Copyright © 2006 Elsevier B.V. All rights reserved.
IVESTIGATION OF PERMEATION TUBES FOR TEMPERATURE-COMPENSATED GAS-SENSOR CALIBRATORS.
G.Neri, A.Bonavita, G.Rizzo, G. Micali, N. Donato, S.Ipsale,
Ethanol permeation tubes have been proposed for a possible use in temperature-compensated gas-sensor calibrators. Two commercial tubes with a different geometric configuration of the polymeric membrane (wafer- and EL-type) have been tested. First, their permeation characteristics have been evaluated and, subsequently, their performances tested in an apparatus simulating programmed temperature cycles. Both tubes have shown a linear permeation rate in the range of temperature investigated and a low permeation temperature coefficient, with the EL-type tube showing also a very fast response to temperature variation. The integration of this latter tube with a flow-compensation controller has lead to the realization of a temperature-compensated calibrator device, allowing to maintain the ethanol concentration constant at the calibrator outlet by simply modulating the carrier flow through the permeation tube to compensate the temperature fluctuation. Results obtained in the generation of calibrated gas-phase ethanol concentrations, in the range from 1 to 500 ppm, suggest a promising use of these temperature-compensated permeation tubes as calibrators in portable gas-sensor devices.
Sensors Journal, IEEE
Volume: 6 Issue: 5 Oct. 2006
Page(s): 1120- 1125
Digital Object Identifier 10.1109/JSEN.2006.881347
TEMPERATURE-INDEPENDENT PERMEATION TUBES FOR GAS SENSOR CALIBRATORS.
S.Galvagno,* G.Neri,* A.Bonavita,* G.Rizzo,* G. Micali,* N. Donato,* S.Ipsale*
*Dept. of Ind. Chem. & Mater. Eng., Messina Univ., Italy;
A new temperature-independent set-up for gas sensors calibration making use of permeation tubes is proposed. The control of the output gas-phase concentration from the calibrator was made modulating the carrier flow through the permeation tube as a function of the temperature and dynamic of the tube by an entirely computer-controlled system. The study and results related to generation of calibrated gas-phase ethanol concentrations (from 1 to 500 ppm) and the calibration of a MOS (metal oxide semiconductor) gas sensor by this apparatus have been reported.
Sensors, 2004. Proceedings of IEEE
Publication Date: 24-27 Oct. 2004
On page(s): 734- 737 vol.2