1,721,053 research outputs found
Electrochemically growth of Pd doped ZnO nanorods on QCM for room temperature VOC sensors
No full textPristine and various palladium (Pd) doped ZnO nanorods have been synthesized on the quartz crystal microbalance (QCM) for volatile organic compound (VOCs) sensors at room temperature. The doping concentrations were varied from 0 mol% to 2.5 mol% by using electrochemical deposition method. The diameters of the fabricated nanorods were in the range of 100-200 nm, and were increased with Pd doping. The tested VOCs included alcohols (ethanol, methanol, isopropyl), ester (ethyl acetate), aromatic (toluene, xylene), ketone (acetone) and chloroform in the different concentrations. The results indicated that the sensitivity of the sensing materials was enhanced with the increasing Pd doping concentrations except for the acetone and chloroform. The undoped ZnO nanorod sensor showed higher sensor response against to acetone and chloroform while exposing high concentration of two analytes due to the absorbing/adsorbing mechanism. All undoped and Pd doped nanorods sensors showed the highest sensitivity to xylene. © 2015 Published by Elsevier B.V
COST action TD1105: New sensing technologies for environmental sustainability in smart cities
No full textThis paper gives a detailed technical overview on some new sensing technologies for environmental sustainability in the context of the smart cities. COST Action TD1105 EuNetAir is the European networking framework to discuss a research roadmap for new sustainable technologies applied to the air quality monitoring, indoor/outdoor energy efficiency, odour monitoring, CO2 detection for industrial applications, and automotive air quality measurements. The main aim of the concerted Action EuNetAir, funded by COST EU program, is to create an international network of world-class experts in a multidisciplinary approach to define challenging research and innovation needs related to the new sensing technologies for air-pollution and environmental sustainability. The key-technologies for supporting environmental sustainability are the low-cost, low-power and accurate sensors to provide pervasive technologies distributed in the smart cities by engaging citizens' community for enhanced awareness in the clean environment and green energy. These efforts impact on future improved quality of life in Europe supporting green-economy and sustainable development. © 2014 IEEE
COST Action TD1105 - European Network on New Sensing Technologies for Air Pollution Control and Environmental Sustainability. Overview and Plans
No full textAbstractThis is a short overview of the COST Action TD1105 EuNetAir - European Network on New Sensing Technologies for Air-Pollution Control and Environmental Sustainability - funded in the framework European Cooperation in the field of Scientific and Technical Research (COST) during the period 2012-2016.The main objective of the Concerted Action is to develop new sensing technologies for Air Quality Control at integrated and multidisciplinary scale by coordinated research on nanomaterials, sensor-systems, air-quality modelling and standardised methods for supporting environmental sustainability with special focus on SMEs. This international Networking, coordinated by ENEA (Italy), includes over 120 big institutions and over 200 international experts from 31 COST Countries (EU-zone) and 7 Non-COST Countries (extra-Europe) to create a S&T critical mass in the environmental issues
Assessment of the Performance of a Low-Cost Air Quality Monitor in an Indoor Environment through Different Calibration Models
Full text linkAir pollution significantly affects public health in many countries. In particular, indoor air quality can be equally, if not more, concerning than outdoor emissions of pollutant gases. However, monitoring the air quality in homes and apartments using chemical analyzers may be not affordable for households due to their high costs and logistical issues. Therefore, a new alternative is represented by low-cost air quality monitors (AQMs) based on low-cost gas sensors (LCSs), but scientific literature reports some limitations and issues concerning the quality of the measurements performed by these devices. It is proven that AQM performance is significantly affected by the calibration model used for calibrating LCSs in outdoor environments, but similar investigations in homes or apartments are quite rare. In this work, the assessment of an AQM based on electrochemical sensors for CO, NO2, and O3 has been performed through an experiment carried out in an apartment occupied by a family of four during their everyday life. The state-of-the-art of the LCS calibration is featured by the use of multivariate linear regression (MLR), random forest regression (RF), support vector machines (SVM), and artificial neural networks (ANN). In this study, we have conducted a comparison of these calibration models by using different sets of predictors through reference measurements to investigate possible differences in AQM performance. We have found a good agreement between measurements performed by AQM and data reported by the reference in the case of CO and NO2 calibrated using MLR (R2 = 0.918 for CO, and R2 = 0.890 for NO2), RF (R2 = 0.912 for CO, and R2 = 0.697 for NO2), and ANN (R2 = 0.924 for CO, and R2 = 0.809 for NO2)
Evaluation of gas-sensing properties of ZnO nanostructures electrochemically doped with Au nanophases
No full textA one-step electrochemical method based on sacrificial anode electrolysis (SAE) was used to deposit stabilized gold nanoparticles (Au NPs) directly on the surface of nanostructured ZnO powders, previously synthesized through a sol-gel process. The effect of thermal annealing temperatures (300 and 550 °C) on chemical, morphological, and structural properties of pristine and Au-doped ZnO nancomposites (Au@ZnO) was investigated. Transmission and scanning electron microscopy (TEM and SEM), as well as X-ray photoelectron spectroscopy (XPS), revealed the successful deposition of nanoscale gold on the surface of spherical and rodlike ZnO nanostructures, obtained after annealing at 300 and 550 °C, respectively. The pristine ZnO and Au@ZnO nanocomposites are proposed as active layer in chemiresistive gas sensors for low-cost processing. Gas-sensing measurements towards NO2 were collected at 300 °C, evaluating not only the Au-doping effect, but also the influence of the different ZnO nanostructures on the gassensing properties. © 2016 Dilonardo et al
Tetra-tert-butyl copper phthalocyanine-based QCM sensor for toluene detection in air at room temperature
No full textThe sensing properties of tetra-tert-butyl copper phthalocyanine (ttb-CuPc) toward toluene at room temperature are reported in this manuscript. Thin films of ttb-CuPc were obtained by thermal evaporation. The similarities between powdered and layered material have been con.rmed by FTIR analysis. Taking into consideration the interactions involved between material and the target gas, Quartz Crystal Microbalance (QCM) was chosen as transducer. The key role of tertiary butyl groups grafted at the periphery of the phthalocyanine ring on toluene sensitivity has been firstly established. Despite reproducible frequency shifts for toluene exposures at the same concentration, sensor drifts were observed and attributed to temperature effects on quartz crystal. Such thermal in.uence on sensor responses has been minimized by short exposure times and temperature compensation on sensor signal. The strong affinity of ttb-CuPc to toluene as compared to other phthalocyanines, the repeatability of sensor responses, the reversibility of involved gas/material interactions, a resolution higher than 10 ppm and a threshold of detection lower than 35 ppm have been established from experiments. The partial selectivity has been also highlighted toward others gases like CO, NO2, H2S and xylene. At last, the relevance of metallo-phthalocyanine thin films as sensitive coatings on QCM devices to detect volatile organic compounds in real-time situation will be discussed. © 2015 Elsevier B.V. All rights reserved
Design and Development of a Flexible, Plug-and-Play, Cost-Effective Tool for on-Field Evaluation of Gas Sensors
Full text linkAtmospheric pollution is one of the biggest concerns for public health. Air quality monitoring is currently performed by expensive and cumbersome monitoring stations. For this reason, they are sparse, and therefore, inadequate to provide enough accurate information on the personal exposure to pollutant gases. The current worldwide trend to address this issue consists in the use of low-cost small gas sensors, already available on the market, with a wide range of costs and performances. However, the performance of these sensors is heavily affected by the environmental conditions of the specific location used for their deployment. For this reason, it is of fundamental importance to test them in real-world scenarios. Field evaluation of sensor performance could be a challenging task because, on the one hand, they have heterogeneous output signals, and on the other hand, there is no widely shared evaluation protocol. The SentinAir system has been designed and developed to facilitate this task. It can carry out performance evaluations for any type of sensor thanks to its configurable and adaptable sensing capability, multiple wireless sensor network compatibility, flexibility, and usability. In order to evaluate SentinAir capabilities and functionalities, the performances of CO2, NO2, and O3 sensors were tested in real-world scenarios against reference instruments. To the best of our knowledge, there is no previous study providing information about the performance of SP-61 (O3 sensor), IRC-A1 (CO2 sensor), and TDS5008 (CO2 sensor) achieved during on-field tests. On the contrary, results obtained by OXB431 (O3 sensor) and NO2B43F (NO2 sensor) are consistent with the ones shown in previous studies carried out in similar conditions. During validation tests, we have found R2=0.507 for the best performing NO2 sensor, and R2=0.668 for the best O3 sensor. Concerning the indoor experiment, the best CO2 sensor performance showed an excellent R2=0.995. In conclusion, the effectiveness of this tool in evaluating the performance of heterogeneous gas sensors in different real-world scenarios has been demonstrated. Therefore, we anticipate that the use of SentinAir will facilitate researchers to carry out these challenging tasks
Sensing properties of MWCNTs layers electrodecorated with metal nanoparticles for detection of aromatic hydrocarbon compounds
No full textAn electrophoretic process is proposed to deposit electrochemically-preformed Au or Pd NPs, with controlled size, directly on MWCNTs-based chemiresistors to improve the detection of aromatic pollutants, compared to pristine ones. The sensing properties of pristine and functionalized MWCNTs were evaluated at an operating temperature of 40°C towards various concentrations of one aromatic pollutant, belonging to the dangerous BTEX class of compounds, m-Xylene. The sensing performance was related to the metal used in the functionalization process. Metal-doped MWCNTs sensors exhibited a very high gas sensitivity to m-Xylene even at low (80 ppb) concentration at low operating temperature (40°C), good reversibility and repeatability, with the sensing properties controlled by the type of deposited metal catalyst. The results indicate that Metal-modified MWCNT-based chemiresistive gas sensors has good potential in practical applications, due to its remarkable performance, low power consumption, and facile synthesized methods. © 2017 Materials Research Society
Enhanced gas sensing properties of chemiresistors based on ZnO nanorods electrodecorated with Au and Pd nanoparticles
No full textColloidal Au and Pd nanoparticles (NPs) were directly electrochemically synthesized, by sacrificial anode electrolysis (SAE), on hydrothermal ZnO nanostructures, previously desiccated; further, the functionalized ZnO nanostructures were subjected to thermal annealing at 550°C to obtain stable ZnO nanorods (NRs), superficially decorated by naked metal NPs. The both pristine and metal functionalized ZnO NRs were proposed as active layer in chemiresistive sensors for environmental monitoring to detect pollutant gases (e.g. NO2, C4H10). The effect of the presence and of the chemical nature of the deposited metal NPs on the performance of ZnO NRs-based gas sensor (e.g. sensitivity, selectivity and recovery) was evaluated, comparing the sensing results with those of pristine ZnO NRs. In particular, the gas sensing properties of pristine and metal-functionalized ZnO NRs were studied at an operating temperature of 300°C towards a various range of concentration of different gaseous pollutants. © 2017 Materials Research Society
Sensitive detection of hydrocarbon gases using electrochemically Pd-modified ZnO chemiresistors
No full textPristine and electrochemically Pd-modified ZnO nanorods (ZnO NRs) were proposed as active sensing layers in chemiresistive gas sensors for hydrocarbon (HC) gas detection (e.g., CH4, C3H8, C4H10). The presence of Pd nanoparticles (NPs) on the surface of ZnO NRs, obtained after the thermal treatment at 550 °C, was revealed by morphological and surface chemical analyses, using scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. The effect of the Pd catalyst on the performance of the ZnO-based gas sensor was evaluated by comparing the sensing results with those of pristine ZnO NRs, at an operating temperature of 300 °C and for various HC gas concentrations in the range of 30-1000 ppm. The Pd-modified ZnO NRs showed a higher selectivity and sensitivity compared to pristine ZnO NRs. The mean sensitivity of Pd-modified ZnO NRs towards the analyzed HCs gases increased with the length of the hydrocarbon chain of the target gas molecule. Finally, the evaluation of the selectivity revealed that the presence or the absence of metal nanoparticles on ZnO NRs improves the selectivity in the detection of specific HCs gaseous molecules. © 2017 Dilonardo et al
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