Materials and Applications for Sensors and Transducers

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作者: Saci Messaadi, Mosbah Daamouche, Abderrahim Guittoum, Hadria Medouer, Noureddine Fenineche, Ibtissem Zidani
摘要: The aim of this work is to understand the early stages in the growth mechanism of invar (Fe64Ni34) alloys and also to study the influence of potential on the evolution of their crystalline structures. Fe64Ni34 layers were deposited onto copper substrates under optimal conditions using the electrochemical method of cyclic voltammetry (CV) and chronoamperometry (CA). The influence of the potential is examined and the nucleation kinetics is discussed. In this purpose, the obtained experimental data was interpreted by applying useful theoretical methods developed by Scharifker and Hills. X-ray diffraction experiments were performed on all samples in order to follow the structural evolution of Fe64Ni34 layers as a function of the potential.
作者: Sie Chin Tjong
摘要: Poly (vinylidene fluoride)/graphite nanoplatelets (PVDF/GNP) and PVDF/clay nanocomposites were prepared by means of solution mixing and compression molding processes. The effects of graphite and clay nanoplatelet additions on dielectric behavior of PVDF were studied. The results showed that both clay and GNP additions were beneficial in enhancing permittivity of PVDF. However, conducting graphite platelets were more effective than nonconducting clay sheets in this aspect. This was due to the formation of mini-capacitors in the matrix of PVDF/GNP nanocomposites.
作者: Robert Olejnik, Petr Slobodian, Petr Saha
摘要: Multiwall carbon nanotubes (MWCNT) network “Buckypaper” was made by the vacuum filtration method of MWCNT aqueous suspension. The sensitivity of multi-wall carbon nanotube (MWCNT) networks of randomly entangled pure nanotubes to various organic solvent vapors (tetrahydrofuran, methyl ethyl ketone, and ethanol) has been investigated by resistance measurements. The results demonstrate that the network electrical resistance increases when exposed to organic solvent vapors, and a reversible reaction is observed when the sample is removed from the vapors. The investigated MWCNT networks could be potentially used as sensing elements for sensitive and selective organic vapor detection.
作者: Fardad Azarmi, Ghodrat Karami
摘要: Recently, there has been a huge interest in application of thermal spraying processes to apply a protective layer on the surface of engineering components. Thermal spraying as a near net shape forming technique has also found applications in manufacturing of advanced engineering components. Spraying methods such as High Velocity Oxygen Fuel (HVOF), Vacuum Plasma Spraying (VPS), and Air Plasma Spraying (APS) are among the most commonly used deposition techniques. Coatings are built up from impact of molten particles on the substrate surface and their flattening and solidification (splat formation). Deposition of millions of individual splats connected to each other at different layers will result in a lamellae type structure. This is a typical example of an anisotropic microstructure. The microstructural features such as porosity, oxide layers define the physical and mechanical properties of coating material. This study investigates the influence of substrate temperature on microstructural characteristics of APS deposited superalloy 625 on steel substrate. The coatings were deposited on substrates at different temperatures. The porosity level was measured using prosimetry. Both image analysis technique and Electron Probe Microanalysis (EPMA) was used to measure the amount of oxide phase. The results indicated that lower substrate temperature results in lower oxide in microstructure. There has been no significant change in porosity level due to substrate temperature.
作者: Mehdi Mohamadzade Lajvardi, Faramarz Hossein-Babaei, Farhad Akbari Boroumand
摘要: A UV-sensitive Schottky diode of Ag-rutile-Ti structure is fabricated on a thermally oxidized titanium chip. The junction is formed by the thermal evaporation of silver in vacuum and a subsequent controlled annealing process. Applying a biasing voltage of-300 mV, the reverse current of the fabricated silver-rutile-titanium structure increases five orders of magnitude under 50 µW/mm2 UV illumination ( λ=355 nm). The device is visible-blind and its operation is described based on the photoelectric mechanism in the carrier-depleted oxide layer. The dominance of the photoelectric, rather than photoconductive, mechanism along with the dense rutile layer are responsible for the fast transient times observed. The response and recovery times of the device are 800 µs and 7 ms, respectively.The device is stable and extremely cost effective.
作者: Marina C. Terzi, Damianos P. Sakas, Dimitrios Vlachos
摘要: The paper considers the role of Integrated Marketing Communication in enhancing the brand awareness of high-tech laboratories. By acknowledging the great interaction of public and private laboratories with high-tech companies, the study is aimed at developing a simulation model to be incorporated in the marketing strategy of laboratories. The comprehensive dynamic simulation model that was developed highlights the emphasis that should be placed when B2B marketing activities are the matter of concern. Marketing Dynamic Simulation Modelling is based on the principles of Integrated Marketing. It has been tested in both private and public laboratories, concluding that marketing in the private sector receives more attention than in the public sector. The proposed model incorporates all the components for successfully marketing laboratories by taking their budget restrictions into consideration.
作者: Jing Jing Yang, Ming Huang, Jun Sun, Jun Dong Yang
摘要: Sensor utilizing metamaterials have opened up a new field of considerable interest. We extend here the works of our group about metamaterial sensor based on Whispering Gallery Mode (WGM), which is constructed with a microring resonator sensor coated with metamaterial layer. We demonstrate that our sensor possesses higher sensitivity than the traditional sensor since the amplification and penetration of evanescent wave by metamaterials.
作者: Radwa R. Abdel Chafy, Mustafa H. Arafa, Amal M. K. Esawi
摘要: Carbon Nanotubes (CNTs) have shown remarkable electrical, piezoresistive properties as well as other physical properties. The aim of this study is to investigate the potential of CNT-polymer composites in strain sensing using low density polyethylene (LDPE) polymer. Different CNT loadings were used (0, 1, 2, 3.5, 5, 6.5 and 8 weight %). CNT/LDPE composite films of 1mm thickness were fabricated using compression molding. The electrical resistance at no load condition was measured and the percolation behavior was obtained. The percolation threshold was found to be in the range of (2-5) wt%, where a decrease in resistivity by 5 orders of magnitude was observed. The sensitivity (gauge factor – GF) of the films was evaluated by correlating the strain applied with the simultaneously measured resistance. For a strain range of up to 320 µε, a gauge factor of 200 was achieved at a CNT loading of 5 wt%.
作者: Vittorio Elia, Elena Napoli
摘要: This work presents some experimental results on the variation of the physico-chemical properties of pure, twice distilled water, when subject to a procedure of iterative filtrations through Pyrex glass filters (Büchner funnels). The study involves the determination of electrical conductivity. After the filtrations, electrical conductivity increases three times. Part of those increases, about 10-30%, is to be attributed to impurities released by the glass filters. The hypothesis is that the remaining 70-90% of the increases comes from variations in the super-molecular structure of water. The iterative filtration procedure involves a flux of energy and material in an open system. The energy flux is partially dissipated as heat permitting the formation of “dissipative structures”. Water, the main ingredient of living systems, exhibits an extraordinary auto-organization potentiality triggered by several kinds of perturbations, including mechanical ones.