Thin-Film Gauges Using Carbon Nanotubes as Composite Layers
01 Oct 2016-Journal of Engineering Materials and Technology-transactions of The Asme (American Society of Mechanical Engineers)-Vol. 138, Iss: 4, pp 041014
About: This article is published in Journal of Engineering Materials and Technology-transactions of The Asme.The article was published on 2016-10-01. It has received 15 citations till now. The article focuses on the topics: Carbon nanotube & Thin film.
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TL;DR: The results establish the aptness of the as-grown CNT film to be used as an active sensing material in thin film temperature sensors.
Abstract: In this paper, we present the fabrication of an efficient thin film temperature sensor utilizing chemical vapor deposited carbon nanotube (CNT) film as the sensing element on Si substrates, with diamond-like carbon (DLC):Ni as a catalyst in assisting CNT growth. The fabricated sensor showed good electrical response with change in temperature. Relative linear change in resistance of 18.4% for an increase in temperature from 22 °C to 200 °C was achieved. Various characterizing techniques, such as scanning electron microscopy (SEM) and Raman spectroscopy, were used to characterize the films. In an effort to study device performance, van der Pauw and Hall measurements were carried out to study the dependence of resistance on temperature and magnetic fields. Temperature coefficient of resistance of the sensor was calculated as 1.03 × 10-3/°C. All implications arising from the study are presented. The results establish the aptness of the as-grown CNT film to be used as an active sensing material in thin film temperature sensors.
20 citations
Cites background from "Thin-Film Gauges Using Carbon Nanot..."
...In previous studies, researchers have confirmed the enhancement of thermal and electrical conduction of a silver thin film sensor by adding small amounts of com ercially available multiwalled carbon nanotubes (MWCNTs) to silver [1]....
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...Previous research has shown the possibility of commercially available carbon nanotubes (CNT) mixed with silver pastes to be used as an active sensing element in TFS [1]....
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...In previous studies, researchers have confirmed the enhancement of thermal and electrical conduction of a silver thin film sensor by adding small amounts of commercially available multiwalled carbon nanotubes (MWCNTs) to silver [1]....
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...The theory states that the ratio of film thickness to substrate thickness should be such that, during the experimental run time, the heat does not have sufficient time to penetrate throughout the substrate [1]....
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TL;DR: In this paper, multi-walled carbon nanotubes (MWCNTs) are mixed with platinum while making the TFHFSs to increase the sensitivity and decrease the temperature coefficient of resistance of the thin film sensors.
Abstract: Surface heat transfer measurement is an important aspect in many research problems. Thin film heat flux sensor (TFHFS) is mostly considered in such situations for heat flux measurement due to its quick response and high accuracy. In the present studies, multi-walled carbon nanotubes (MWCNTs) are mixed with platinum while making the TFHFSs. Such addition is noticed to increase the sensitivity and decrease the temperature coefficient of resistance (TCR) of the thin film sensors. Improved sensitivity by 151% and 119% for Macor and Quartz sensors has led to increase in strength of the temperature response of the sensors during dynamic calibration experiments. Though heat flux recovery is seen to have encouraging agreement for all the sensors, sensitivity enhancement is noticed to be more prominent and advantageous for Macor based sensors. Present studies recommend adequately finished substrate for better adhesion. Further, use of MWCNTs is advisable especially for low heat flux measurement and also for Macor substrate since either situation demands the higher sensitivity to increase the output response.
8 citations
TL;DR: In this paper, the adaptive neural fuzzy inference system (ANFIS) and genetic programming (GP) were used to estimate heat fluxes for three thin film gauges made from Ag, Au, CNT/Ag nano-composite topped on insulating substrate.
7 citations
TL;DR: In this article, the authors developed an Ag-Carbon nanotube (CNT) nanocomposite film as the sensing element of a TFS and compare it with pure Ag TFS, both having Macor as substrate.
7 citations
TL;DR: In this paper, a low pressure chemical vapor deposition system was employed for synthesizing carbon nanotubes (CNT) and nickel on Si (1 0 0) substrates and justifies their use in thin film temperature sensors.
Abstract: This study reports a novel approach for growing multilayer thin films consisting of alternate layers of carbon nanotubes (CNT) and nickel on Si (1 0 0) substrates and justifies their use in thin film temperature sensors. A low pressure chemical vapor deposition system was employed for synthesizing CNT films, while Ni films were deposited by electrodeposition. Porous-Si was used as substrate to increase adhesion between the layers of the multilayer structure. The structure of the multilayer films and the quality of the CNT grown were analyzed using several characterization methods, including scanning electron microscopy, x-ray photoelectron spectroscopy, x-ray auger electron spectroscopy and Raman spectroscopy. The electrical characteristics were investigated using a van der Pauw setup and the effect of the increasing number of CNT layers in the multilayer structure was studied. The sensitivity of the multilayer film was found to increase with increasing number of CNT layers, despite the decrease of the temperature coefficient of resistance. On the other hand, the initial resistance was found to increase. Results indicated that these multilayer structures are appropriate for fabricating highly sensitive thin film gauges that can detect lower heat fluxes with more accuracy.
5 citations
References
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TL;DR: In this paper, the authors measured the effective thermal conductivity of mixtures of Al 2O3 and CuO, dispersed in water, vacuum pump, engine oil, and ethylene glycol.
Abstract: Effective thermal conductivity of mixtures of e uids and nanometer-size particles is measured by a steady-state parallel-plate method. The tested e uids contain two types of nanoparticles, Al 2O3 and CuO, dispersed in water, vacuum pump e uid, engine oil, and ethylene glycol. Experimental results show that the thermal conductivities of nanoparticle ‐e uid mixtures are higher than those of the base e uids. Using theoretical models of effective thermal conductivity of a mixture, we have demonstrated that the predicted thermal conductivities of nanoparticle ‐e uid mixtures are much lower than our measured data, indicating the dee ciency in the existing models when used for nanoparticle ‐e uid mixtures. Possible mechanisms contributing to enhancement of the thermal conductivity of the mixtures are discussed. A more comprehensive theory is needed to fully explain the behavior of nanoparticle ‐e uid mixtures. Nomenclature cp = specie c heat k = thermal conductivity L = thickness Pe = Peclet number P q = input power to heater 1 r = radius of particle S = cross-sectional area T = temperature U = velocity of particles relative to that of base e uids ® = ratio of thermal conductivity of particle to that of base liquid ¯ = .® i 1/=.® i 2/ ° = shear rate of e ow Ω = density A = volume fraction of particles in e uids Subscripts
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TL;DR: A review on fluid flow and heat transfer characteristics of nanofluids in forced and free convection flows is presented in this article, where the authors identify opportunities for future research.
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TL;DR: In this paper, the authors summarized the important published articles on the enhancement of the forced convection heat transfer with nanofluids, including simulations, simulations, and experimental results.
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Abstract: In the laser treatment of a workpiece (9), e.g. for surface hardening, melting, alloying, cladding, welding or cutting, the adverse effect of reflectivity of the surface, when a pure, monochromatic laser (6) is used, is remedied by the simultaneous application of a relatively shorter wavelength beam (1). The two beams (1)(5) may be combined by a beam coupler (4) or may reach the workpiece (9) by separate optical paths (not shown). The shorter wavelength beam (1) improves the coupling efficiency of the higher- powered laser beam (5).
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