1,118 research outputs found
SiC Foams Decorated with SnO2 Nanostructures for Room Temperature Gas Sensing
No full textSberveglieri, Giorgio/0000-0003-0080-8117; Ponzoni, Andrea/0000-0001-9955-5118; Comini, Elisabetta/0000-0003-2559-5197; Vakifahmetoglu, Cekdar/0000-0003-1222-4362Cell walls of the commercial silicon carbide (SiC)-based foams were decorated by one-dimensional tin dioxide (SnO2) nanostructures. Thermal evaporation of SnO2 powder with the assistance of a Au catalyst in inert atmosphere caused the formation of SnO2 nanobelts on the pore surfaces. The room temperature (RT) ammonia (NH3) and nitrogen dioxide (NO2) gas sensing behaviors were investigated systematically in both dry and humid air atmosphere with/without UV activation. The results were compared to those for bare SnO2 and SiC. It was shown that SiC/SnO2 composite was efficient to detect low concentration of NH3 (10-50 ppm) and NO2 (1-5 ppm) under humid air and UV activation at RT.TUBITAK (The Scientific and Technological Research Council of Turkey)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [CAYDAG-113Y533]The author wishes to express sincere appreciation to Prof. Gian Domenico Soraru and his team in University of Trento for the N2 adsorption and desorption data. C. V. gratefully acknowledge the support of TUBITAK (The Scientific and Technological Research Council of Turkey) under the project Grant No. CAYDAG-113Y533
"Nanosensors" - Editorial
No full textNowadays we rely heavily on sensors for a lot of activities in our life. For example, sensors in our mobile phone detect our position, movements, environmental conditions such as humidity level, recognize our intentions and do things on our behalf..
Integration of Metal Oxide Nanowires in Flexible Gas Sensing Devices
No full textMetal oxide nanowires are very promising active materials for different applications, especially in the field of gas sensors. Advances in fabrication technologies now allow the preparation of nanowires on flexible substrates, expanding the potential market of the resulting sensors. The critical steps for the large-scale preparation of reliable sensing devices are the elimination of high temperatures processes and the stretchability of the entire final device, including the active material. Direct growth on flexible substrates and post-growth procedures have been successfully used for the preparation of gas sensors. The paper will summarize the procedures used for the preparation of flexible and wearable gas sensors prototypes with an overlook of the challenges and the future perspectives concerning this field
Metal oxide nano-crystals for gas sensing
No full textThis review article is focused on the description of metal oxide single crystalline nanostructures used for gas sensing. Metal oxide nano- wires are crystalline structures with precise chemical composition, surface terminations, and dislocation-defect free. Their nanosized dimension generate properties that can be significantly different from their coarse-grained polycrystalline counterpart. Surface effects appear because of the magnification in the specific surface of nanostructures, leading to an enhancement of the properties related to that, such as catalytic activity or surface adsorption. Properties that are basic phenomenon underlying solid-state gas sensors.
Their use as gas-sensing materials should reduce instabilities, suffered from their polycrystalline counterpart, associated with grain coalescence and drift in electrical properties. High degree of crystallinity and atomic sharp terminations make them very promising for better understanding of sensing principles and for development of a new generation of gas sensors. These sensing nano-crystals can be used as resistors, in FET based or optical based gas sensors. The gas experiments presented confirm good sensing properties, the possibility to use dopants and catalyser such in thin film gas sensors and the real integration in low power consumption transducers of single crystalline nanobelts prove the feasibility of large scale manufacturing of well-organized sensor arrays based on different nanostructures. Nevertheless, a greater control in the growth is required for an application in commercial systems, together with a thorough understanding of the growth mechanism that can lead to a control in nano-wires size and size distributions, shape, crystal structure and atomic termination
Metal oxide nanowire chemical sensors: innovation and quality of life
No full textMetal oxides are emerging as important active materials for applications
such as sensors. Recent advances in the preparation of metal oxide
materials offer unique possibilities for their integration into devices
with new capabilities, for example, wearable/flexible devices, smart
textiles for well-being and health monitoring in everyday life, or with
innovative sensing architectures such as work function, surface
ionization, magnetic, self-heating, and Schottky-based devices. This
review presents the author's opinion on innovations and challenges in
the field of metal oxide nanowire chemical sensors
Metal oxide nanowires as chemical sensors
No full textIt is almost a decade since the first presentation of metal oxide nanowires as chemical sensors. Significant advances have been made both in
terms of preparation procedures and their integration into functional sensing devices, whilst the progress in their fundamental understanding
of functional properties has been slow. In fact, the full integration still remains a challenge that has been wisely approached in different ways. In this article we review the most recent developments in bottom up and top down approaches for applications of chemical sensors
Investigation on the O-3 sensitivity properties of WO3 thin films prepared by sol-gel, thermal evaporation and r.f. sputtering techniques
No full textWO3 thin films have been deposited on alumina substrates provided with platinum interdigital electrodes by sol-gel (SG), r.f. sputtering (RFS), and vacuum thermal evaporation (VTE) techniques and annealed at temperatures between 500 degrees C and 600 degrees C for 1 to 30 h in static air. The morphology, crystalline phase and chemical composition of the films have been characterised using SEM, glancing XRD and XPS techniques. The electrical response has been measured exposing the films to O-3 (10-180 ppb), NO2 (0.2-1 ppm), NOx (27 ppm NO and 1 ppm NO,) at different operating temperatures ranging between 200 and 400 degrees C and humid air at 50% R.R. SG prepared films have shown bigger responses (S = I-Air/I-gas) with respect to VTE and RFS for all the investigated gases and operating temperatures. RFS prepared has resulted to be less sensitive, but faster in the response and more stable in terms of signal reproducibility. The response to O-3 has been found to be at maximum at 400 degrees C. At this temperature the response to 80 ppb of ozone has been: S = 35 (SG), S = 18 (VTE) and S = 5 (RFS). The NO2 and NOx response reached the maximum at 200 degrees C and becomes negligible at 400 degrees C. Improvements on the O-3 gas sensitivity and selectivity can be achieved by fixing the operating temperature of the films at 400 degrees C. (C) 2000 Elsevier Science S.A. All rights reserved. RI Faglia, Guido/E-6991-2010; Sberveglieri, Giorgio/A-5030-2010; li , yongxiang/C-5059-2009; Comini, Elisabetta/C-6721-200
Thermally oxidized zinc oxide nanowires for use as chemical sensors
No full textZinc oxide (ZnO) mat-based conductometric devices were fabricated using a thermal oxidation technique. A metallic zinc layer was deposited on the alumina transducer and then oxidized in a controlled atmosphere, in order to obtain ZnO nanostructures. Two different batches of sensors have been prepared, and their sensing performances have been evaluated towards oxidizing and reducing gases. Functional measurements showed very good sensing performances towards ethanol and acetone at 500°C, and NO2 at 200°C, indirectly confirming the n-type behaviour of the material. The influence of the humidity on the response has been explored. In practical conditions the interference of humidity is very small, and could be neglected in many applications. Simultaneous measurements on different devices from the same batch confirm the high reproducibility of the response within the batch. © 2013 IOP Publishing Ltd
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