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Jul 2007

Volume 78, Issue 7, Articles (07xxxx)

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Apparatus to study the onset of free convection about vertical and inclined hot wires

Valter Giaretto, Elio Miraldi, and Marco F. Torchio

Rev. Sci. Instrum. 78, 074901 (2007); http://dx.doi.org/10.1063/1.2754401 (6 pages) | Cited 1 time

Online Publication Date: 10 July 2007

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This article describes a methodology and an apparatus used to evaluate the onset time of free convection in hot-wire experiments. The evaluation of the onset time is useful to obtain a measurement interval that is suitable to estimate the thermal properties of a fluid. If a pure conduction regime is present, the hot-wire temperature increment versus time is a straight line in a semilog plot, whereas the convection effect induces a deviation from this trend. An algorithm based on the F test is proposed to evaluate the onset time of free convection. The experimental facility has the particular feature of allowing an easy change of the hot-wire inclination angle up to 118.3 mrad. The wire is kept in a tilted position by a permanent horseshoe magnet, and the tilting angle from the vertical is measured by a theodolite. Some testing results using water are discussed for vertical and inclined wires. A good agreement between the experimental onset times and the theoretical ones is found in the case of a vertical wire.
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47.80.Fg Pressure and temperature measurements
47.55.pb Thermal convection
07.20.Dt Thermometers

Laser scanning thermoreflectance imaging system using galvanometric mirrors for temperature measurements of microelectronic devices

S. Grauby, A. Salhi, J.-M. Rampnoux, H. Michel, W. Claeys, and S. Dilhaire

Rev. Sci. Instrum. 78, 074902 (2007); http://dx.doi.org/10.1063/1.2757473 (8 pages) | Cited 3 times

Online Publication Date: 25 July 2007

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We present a thermoreflectance imaging system using a focused laser sweeping the device under test with a scanner made of galvanometric mirrors. We first show that the spatial resolution of this setup is submicrometric, which makes it adapted to microelectronic thermal measurements. Then, we studied qualitative temperature variations on two dissipative structures constituted of thin (0.35 μm) dissipative resistors, the distance between two resistors being equal to 0.8 or 10 μm. This technique combines sensitivity and speed: it is faster than a point classical thermoreflectance technique and, in addition, more sensitive than a charge-coupled device thermoreflectance imaging technique.
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07.20.Dt Thermometers
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology
85.60.Gz Photodetectors (including infrared and CCD detectors)

Quartz crystal microbalance based on torsional piezoelectric resonators

W. Bücking, B. Du, A. Turshatov, A. M. König, I. Reviakine, B. Bode, and D. Johannsmann

Rev. Sci. Instrum. 78, 074903 (2007); http://dx.doi.org/10.1063/1.2756740 (8 pages) | Cited 5 times

Online Publication Date: 26 July 2007

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A quartz crystal microbalance (QCM) is described, which is based on a torsional resonator, rather than a conventional thickness-shear resonator. Typical applications are measurements of film thickness in the coating industry and monitoring of biofouling. The torsional QCM is about a factor of 100 less sensitive than the conventional QCM. On the other hand, it can probe film thicknesses in the range of hundreds of microns, which is impossible with the conventional QCM due to viscoelastic artifacts. Data acquisition and data analysis proceed in analogy to the conventional QCM. An indicator of the material’s softness can be extracted from the bandwidth of the resonance. Within the small-load approximation, the frequency shift is independent of whether the sample is applied to the face or to the side of the cylinder. Details of the geometry matter if the viscoelastic properties of the sample are of interest.
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06.30.Dr Mass and density
07.10.Lw Balance systems, tensile machines, etc.
77.65.Fs Electromechanical resonance; quartz resonators
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
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