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Oct 2009

Volume 80, Issue 10, Articles (10xxxx)

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Rev. Sci. Instrum. 80, 101101 (2009); http://dx.doi.org/10.1063/1.3236681 (22 pages)

David D. Nolte

Biodisks are lab-on-a-chip device that spin. The two major types of biodisks are centrifugal microfluidic disks and BioCDs. The microfluidic disks use noninertial forces to pump and switch fluids. The BioCDs use lasers and high-frequency optical sampling to rapidly measure target analytes bound to recognition molecules.

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A microfluidic oscillating tube densitometer

Chloé Marion Coléou, Philip Dryden, and Christopher Harrison

Rev. Sci. Instrum. 80, 105101 (2009); http://dx.doi.org/10.1063/1.3226668 (6 pages)

Online Publication Date: 8 October 2009

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This article discusses a microfluidic oscillating tube densitometer with an internal volume of approximately 20 μl. Accuracy better than +/−0.5% in density is demonstrated over a range of temperatures (50 °C–150 °C) and pressures (150–15 000 psi) by prior calibration with air and water. The flexibility of the tubing facilitates use of a novel actuation and detection system that greatly simplifies the fabrication. Two simple and automated calibration methods are discussed using measurements performed with an evacuated and a water-filled tube. Measurements show that the effective spring constant of the tube is strongly affected by temperature and is largely insensitive to pressure. The tube volume, on the other hand, is strongly affected by pressure.
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47.85.Np Fluidics

Long term thermoelectric module testing system

Jonathan D’Angelo and Timothy Hogan

Rev. Sci. Instrum. 80, 105102 (2009); http://dx.doi.org/10.1063/1.3247901 (3 pages) | Cited 1 time

Online Publication Date: 16 October 2009

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Thermoelectric generators can be used for converting waste heat into electric power. Significant interest in developing new materials in recent years has led to the discovery of several promising thermoelectrics, however, there can be considerable challenges in developing the materials into working devices. Testing and feedback is needed at each step to gain valuable information for identification of difficulties, quality of the materials and modules, repeatability in fabrication, and longevity of the devices. This paper describes a long-term module testing system for monitoring the output power of a module over extended testing times. To evaluate the system, we have tested commercially available thermoelectric modules over a one month time period.
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84.60.Rb Thermoelectric, electrogasdynamic and other direct energy conversion

Deterministic fabrication of carbon nanotube probes using the dielectrophoretic assembly and electrical detection

Donghyun Lim, Soongeun Kwon, Jonghyun Lee, Hyung Cheoul Shim, Hyung Woo Lee, and Soohyun Kim

Rev. Sci. Instrum. 80, 105103 (2009); http://dx.doi.org/10.1063/1.3223348 (5 pages)

Online Publication Date: 16 October 2009

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We report the controlled dielectrophoretic assembly for the deterministic fabrication of carbon nanotube (CNT) probes. Electrical detection was applied to the dielectrophoretic assembly of CNT probes. Dielectrophoretic manipulation with an ac electric field of 5 MHz was used to form the CNT bridge across oppositely aligned tungsten tips (W-tips). A dc electric field was simultaneously applied to monitor the direct current flowing through the gap. The detected nanocurrent reveals that the CNT bridge is formed between W-tips in real time. We compared current data with bundle diameter of CNT probes in field emission scanning electron microscopy (FE-SEM) images. As the number of assembled CNTs increased, current was increased. With the obtained linear relationship, the number of the attached CNTs can be estimated without confirmation of the FE-SEM image. This combined use of the current detection method with dielectrophoretic manipulation will provide a reliable process for the fabrication of CNT probes.
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81.16.-c Methods of micro- and nanofabrication and processing
82.45.-h Electrochemistry and electrophoresis
73.63.Fg Nanotubes
81.07.De Nanotubes
85.35.Kt Nanotube devices

Improvement of spatial resolution for local Seebeck coefficient measurements by deconvolution algorithm

K. H. Wu, C. I. Hung, P. Ziolkowski, D. Platzek, G. Karpinski, C. Stiewe, and E. Mueller

Rev. Sci. Instrum. 80, 105104 (2009); http://dx.doi.org/10.1063/1.3246815 (8 pages) | Cited 4 times

Online Publication Date: 19 October 2009

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A potential Seebeck microprobe apparatus is described such that a profile of Seebeck coefficients can be detected on a material sample surface for thermopower investigations. Due to its spatially resolved limit on detecting small inhomogeneities of dopants or composition changes, we here propose a constructive combination of numerical modeling and practical measurement to improve the spatial resolution by deconvolution algorithm. The relevant transfer function, obtained from numerical calculations, was successfully applied on real measurement data. Besides, an improvement in detecting the 1.5 μm inhomogeneity has been achieved by applying one transfer function of the known tip setup on a set of Seebeck line scan signals, obtained with 6 μm tip-sample contact length, 3 μs signal capture time after contact, and 0.75 μm scan period. The result showed that a system theoretical approach in terms of deconvolution algorithm could theoretically enhance the spatial resolution anyway, but is practically limited by the systemic preconditions (tip size, signal capture time, and scan period) and the signal to noise ratio of the captured thermovoltages. Therefore, we provide a clear understanding of systemic preconditions and their impacts on the detection of small inhomogeneities and thus the performance in the thermopower analysis.
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72.15.Jf Thermoelectric and thermomagnetic effects
71.10.-w Theories and models of many-electron systems
84.32.Hh Inductors and coils; wiring

Original use of a direct injection high efficiency nebulizer for the standardization of liquid fuels spray flames

R. Lemaire, M. Maugendre, T. Schuller, E. Therssen, and J. Yon

Rev. Sci. Instrum. 80, 105105 (2009); http://dx.doi.org/10.1063/1.3249561 (8 pages) | Cited 4 times

Online Publication Date: 28 October 2009

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It is of practical importance to lead laboratory-scale experiments allowing a better understanding of the impact of commercial fuels composition on the formation of combustion residues such as soot particles. To this end, a hybrid burner has been designed recently to burn high-speed sprays of small liquid fuel droplets. It consists of a Holthuis (previously McKenna) burner originally equipped with a direct injection high efficiency nebulizer for the atomization of liquid hydrocarbons. A detailed description of this original setup is given in this paper. A priori estimations of atomization and evaporation times and length scales are then proposed and compared with experimental data. Droplet-size distribution measurements obtained in nonreacting conditions using a Malvern Spraytec particle sizer are presented and compared with values estimated by calculation. Cold sprays contours and liquid jet lengths in flames determined by Mie scattering at 532 and 1064 nm, respectively, are also presented. The results discussed in this work indicate that the hydrodynamic characteristics of the sprays generated with our system are relatively independent of the physical properties of fuels leading to comparable flames with identical liquid jet lengths, dimensions, and global structure. This feature facilitates an accurate comparison of flames burning various liquid hydrocarbons, which is of interest to emphasize differences in pollutants emissions and to highlight chemical effects for soot formation analysis.
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82.33.Vx Reactions in flames, combustion, and explosions
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
47.70.Pq Flames; combustion
47.55.D- Drops and bubbles
47.70.Fw Chemically reactive flows
64.70.fm Thermodynamics studies of evaporation and condensation
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