Passive Micromixers And Organic Electrochemical Transistors For Biosensor Applications,
2011
Louisiana Tech University
Passive Micromixers And Organic Electrochemical Transistors For Biosensor Applications, Senaka Krishna Kanakamedala
Doctoral Dissertations
Fluid handling at the microscale has greatly affected different fields such as biomedical, pharmaceutical, biochemical engineering and environmental monitoring due to its reduced reagent consumption, portability, high throughput, lower hardware cost and shorter analysis time compared to large devices. The challenges associated with mixing of fluids in microscale enabled us in designing, simulating, fabricating and characterizing various micromixers on silicon and flexible polyester substrates. The mixing efficiency was evaluated by injecting the fluids through the two inlets and collecting the sample at outlet. The images collected from the microscope were analyzed, and the absorbance of the color product at the …
Thickness-Shear And Thickness-Twist Vibrations Of An At-Cut Quartz Mesa Resonator,
2011
University of Nebraska-Lincoln
Thickness-Shear And Thickness-Twist Vibrations Of An At-Cut Quartz Mesa Resonator, Huijing He, Jinxi Liu, Jiashi Yang
Department of Mechanical and Materials Engineering: Faculty Publications
We study thickness-shear and thickness-twist vibrations of an AT-cut quartz plate mesa resonator with stepped thickness. The equations of anisotropic elasticity are used with the omission of the small elastic constant c56. An analytical solution is obtained using Fourier series from which the resonant frequencies, mode shapes, and energy trapping are calculated and examined. The solution shows that a mesa resonator exhibits strong energy trapping of thickness-shear and thickness-twist modes, and that the trapping is sensitive to some of the structural parameters of the resonator.
In Vivo Three-Dimensional Blood Velocity Profile Shapes In The Human Common, Internal, And External Carotid Arteries,
2011
University of Nebraska Medical Center
In Vivo Three-Dimensional Blood Velocity Profile Shapes In The Human Common, Internal, And External Carotid Arteries, Alexey Kamenskiy, Yuris A. Dzenis, Jason N. Mactaggart, Anastasia Desyatova, Iraklis I. Pipinos
Department of Mechanical and Materials Engineering: Faculty Publications
Objective: True understanding of carotid bifurcation pathophysiology requires a detailed knowledge of the hemodynamic conditions within the arteries. Data on carotid artery hemodynamics are usually based on simplified, computer-based, or in vitro experimental models, most of which assume that the velocity profiles are axially symmetric away from the carotid bulb. Modeling accuracy and, more importantly, our understanding of the pathophysiology of carotid bifurcation disease could be considerably improved by more precise knowledge of the in vivo flow properties within the human carotid artery. The purpose of this work was to determine the three-dimensional pulsatile velocity profiles of human carotid arteries. …
Ridge Aperture Antenna Array As A High Efficiency Coupler For Photovoltaic Applications,
2011
Birck Nanotechnology Center, Purdue University
Ridge Aperture Antenna Array As A High Efficiency Coupler For Photovoltaic Applications, Edward C. Kinzel, Pornsak Srisungsitthisunti, Xianfan Xu
Birck and NCN Publications
Weak absorption of light near the absorption band edge of a photovoltaic material is one limiting factor on the efficiency of photovoltaics. This is particularly true for silicon thin-film solar cells because of the short optical path lengths and limited options for texturing the front and back surfaces. Directing light laterally is one way to increase the optical path length and absorption. We investigate the use of a periodic array of apertures originated from bowtie aperture antennas to couple incident light into guided modes supported within a thin silicon film. We show the presence of the aperture array can increase …
Isostaticity Of Constraints In Amorphous Jammed Systems Of Soft Frictionless Platonic Solids,
2011
Birck Nanotechnology Center, Purdue University
Isostaticity Of Constraints In Amorphous Jammed Systems Of Soft Frictionless Platonic Solids, Kyle C. Smith, Timothy Fisher, Meheboob Alam
Birck and NCN Publications
The average number of constraints per particle < C(total)> in mechanically stable amorphous systems of Platonic solids approaches the isostatic limit at the jamming point (< C(total)> -> 12), though average number of contacts are hypostatic. By introducing angular alignment metrics to classify the degree of constraint imposed by each contact, constraints are shown to arise as a direct result of local orientational order reflected in edge-face and face-face alignment angle distributions. With approximately one face-face contact per particle at jamming, chainlike face-face clusters form with finite extent-a signature of amorphous jammed systems.
Experimental And Atomistic Theoretical Study Of Degree Of Polarization From Multilayer Inas/Gaas Quantum Dot Stacks,
2011
Tyndall National Institute, Ireland
Experimental And Atomistic Theoretical Study Of Degree Of Polarization From Multilayer Inas/Gaas Quantum Dot Stacks, Muhammad Usman, Tomoya Inoue, Yukihiro Harda, Gerhard Klimeck, Takashi Kita
Birck and NCN Publications
Recent experimental measurements, without any theoretical guidance, showed that isotropic po- larization response can be achieved by increasing the number of QD layers in a QD stack. Here we analyse the polarization response of multi-layer quantum dot stacks containing up to nine quan- tum dot layers by linearly polarized PL measurements and by carrying out a systematic set of multi-million atom simulations. The atomistic modeling and simulations allow us to include cor- rect symmetry properties in the calculations of the optical spectra: a factor critical to explain the experimental evidence. The values of the degree of polarization (DOP) calculated from …
Lifetime Enhanced Transport In Silicon Due To Spin And Valley Blockade,
2011
Kavli Institute of Nanoscience
Lifetime Enhanced Transport In Silicon Due To Spin And Valley Blockade, Gabriel Lansbergen, Rajib Rahman, J. Verdujin, Giuseppe Tettamanzi, Nadine Collaert, Serge Biesemans, Gerhard Klimeck, Lloyd Hollenberg, Sven Rogge
Birck and NCN Publications
We report the observation of Lifetime Enhanced Transport (LET) based on perpendicular valleys in silicon by transport spectroscopy measurements of a two-electron system in a silicon transistor. The LET is manifested as a peculiar current step in the stability diagram due to a forbidden transition between an excited state and any of the lower energy states due perpendicular valley (and spin) configurations, offering an additional current path. By employing a detailed temperature dependence study in combination with a rate equation model, we estimate the lifetime of this particular state to exceed 48 ns. The two-electron spin-valley configurations of all relevant …
Quantitative Analysis Of The Disorder Broadening And The Intrinsic Gap For The V=5/2 Fractional Quantum Hall State,
2011
Purdue University
Quantitative Analysis Of The Disorder Broadening And The Intrinsic Gap For The V=5/2 Fractional Quantum Hall State, N. Samkharadze, J. D. Watson, G. Gardner, Michael J. Manfra, L. N. Pfeiffer, K. W. West, G. A. Csathy
Birck and NCN Publications
We report a reliable method to estimate the disorder broadening parameter from the scaling of the gaps of the even and major odd denominator fractional quantum Hall states of the second Landau level. We apply this technique to several samples of vastly different densities and grown in different molecular beam epitaxy chambers. Excellent agreement is found between the estimated intrinsic and numerically obtained energy gaps for the v = 5/2 fractional quantum Hall state. Furthermore, we quantify the dependence of the intrinsic gap at v = 5/2 on Landau-level mixing.
Nonlinear Thermal Transport And Negative Differential Thermal Conductance In Graphene Nanoribbons,
2011
Birck Nanotechnology Center, Purdue University
Nonlinear Thermal Transport And Negative Differential Thermal Conductance In Graphene Nanoribbons, Jiuning Hu, Yan Wang, Ajit Vallabhaneni, Xiulin Ruan, Yong P. Chen
Birck and NCN Publications
We employ classical molecular dynamics to study the nonlinear thermal transport in graphene nanoribbons (GNRs). For GNRs under large temperature biases beyond linear response regime, we have observed the onset of negative differential thermal conductance (NDTC). NDTC is tunable by varying the manner of applying the temperature biases. NDTC is reduced and eventually disappears when the length of the GNR increases. We have also observed NDTC in triangular GNRs, where NDTC exists only when the heat current is from the narrower to the wider end. These effects may be useful in nanoscale thermal managements and thermal signal processing utilizing GNRs. …
Strain Engineering Via Amorphization And Recrystallization In Si/Ge Heterostructures,
2011
Birck Nanotechnology Center, Purdue University
Strain Engineering Via Amorphization And Recrystallization In Si/Ge Heterostructures, Yumi Park, Winnie Tan, Alejandro Strachan
Birck and NCN Publications
We use molecular dynamics with the reactive potential ReaxFF to study strain relaxation during the amorphization and recrystallization of silicon-germanium epitaxial nanolaminates. Starting with a coherent heterostructure with (010) Si/Ge interfaces and 3D periodic boundary conditions, we use local heating and quenching to amorphize half of the simulation cell with crystal-amorphous interfaces normal to [001]. We find strain relaxation along [001] as the crystalline Ge section expands into the amorphous material and crystalline Si contracts from it. The amount of strain relaxation correlates with the atomic transport from the amorphized Ge to Si section and increases as the periodic width …
Amorphous Interface Layer In Thin Graphite Films Grown On The Carbon Face Of Sic,
2011
Birck Nanotechnology Center, Purdue University
Amorphous Interface Layer In Thin Graphite Films Grown On The Carbon Face Of Sic, R. Colby, M. L. Bolen, Michael A. Capano, E. A. Stach
Birck and NCN Publications
Cross-sectional transmission electron microscopy (TEM) is used to characterize an amorphous layer observed at the interface in graphite and graphene films grown via thermal decomposition of C-face 4H-SiC. The amorphous layer does not cover the entire interface, but uniform contiguous regions span microns of cross-sectional interface. Scanning transmission electron microscopy (STEM) images and electron energy loss spectroscopy (EELS) demonstrate that the amorphous layer is a carbon-rich composition of Si/C. The amorphous layer is clearly observed in samples grown at 1600 degrees C for a range of growth pressures in argon, but not at 1500 degrees C, suggesting a temperature-dependent formation …
Design Of A Gainp/Gaas Tandem Solar Cell For Maximum Daily, Monthly, And Yearly Energy Output,
2011
Purdue University
Design Of A Gainp/Gaas Tandem Solar Cell For Maximum Daily, Monthly, And Yearly Energy Output, Alexander W. Haas, John R. Wilcox, Jeffery L. Gray, Richard J. Schwartz
Birck and NCN Publications
Solar concentrator cells are typically designed for maximum efficiency under the AM1.5d standard spectrum. While this methodology does allow for a direct comparison of cells produced by various laboratories, it does not guarantee maximum daily, monthly, or yearly energy production, as the relative distribution of spectral energy changes throughout the day and year. It has been suggested that achieving this goal requires designing under a nonstandard spectrum. In this work, a GaInP/GaAs tandem solar cell is designed for maximum energy production by optimizing for a set of geographically-dependent solar spectra using detailed numerical models. The optimization procedure focuses on finding …
Role Of Surface Orientation On Atomic Layer Deposited Al2o3/Gaas Interface Structure And Fermi Level Pinning: A Density Functional Theory Study,
2011
Purdue University, Network for Computational Nanotechnology
Role Of Surface Orientation On Atomic Layer Deposited Al2o3/Gaas Interface Structure And Fermi Level Pinning: A Density Functional Theory Study, Ganesh Hegde, Gerhard Klimeck, Alejandro Strachan
Birck and NCN Publications
We investigate the initial surface reaction pathways in the atomic layer deposition (ALD) of Al2O3 on GaAs (111)A and (111)B substrates using precursors trimethylaluminum (TMA) and water to ascertain the effect of surface orientation on device performance. We find that the condition of the respective substrates prior to deposition of TMA and water has a major impact on the surface reactions that follow and on the resulting interface structure. The simulations explain the atomistic mechanism of the interfacial self-cleaning effect in ALD that preferentially removes As oxides. The electronic structure of the resulting atomic configurations indicates states throughout the bandgap …
Synthesis And Characterization Of Highly Textured Pt–Bi Thin Films,
2011
University of Nebraska - Lincoln
Synthesis And Characterization Of Highly Textured Pt–Bi Thin Films, Xingzhong Li, Parashu Kharel, Shah R. Valloppilly, David J. Sellmyer
Nebraska Center for Materials and Nanoscience: Faculty Publications
Pt–Bi films were synthesized on glass and thermally oxidized silicon substrates by e-beam evaporation and annealing. The structures were characterized using X-ray diffraction (XRD) and transmission electron microscopy/selected area electron diffraction (TEM/SAED) techniques. Single-phase PtBi was obtained at an annealing temperature of 300°C, whereas a higher annealing temperature of 400°C was required to obtain the highly textured γ-PtBi2 phase. TEM/SAED analysis showed that the films annealed at 400°C contain a dominant γ-PtBi2 phase with a small amount of β-PtBi2 and α-PtBi2 phases. Both the PtBi and γ-PtBi2 phases are highly textured in these two kinds of film: the c-axis of …
Ferromagnetic Resonance On Ni Nanowire Arrays,
2011
The University of Texas Rio Grande Valley
Ferromagnetic Resonance On Ni Nanowire Arrays, Mircea Chipara, Ralph Skomski, Roger D. Kirby, David J. Sellmyer
Physics & Astronomy Faculty Publications
Ferromagnetic resonance investigations on Ni nanowires are reported. The angular dependence of the resonance line position is analyzed within a thermodynamic approach that includes shape anisotropy (ellipsoids of revolution), magnetocrystalline anisotropies (cubic and uniaxial), and dipole–dipole interactions. The results are supported by hysteresis loops, obtained on the same sample.
Rehabilitation And Exercise Machine,
2011
Madonna Rehabilitation Hospital
Rehabilitation And Exercise Machine, Judith M. Burnfield, Yu Shu, Adam P. Taylor, Thad W. Buster, Carl Nelson
Department of Mechanical and Materials Engineering: Faculty Publications
An improved rehabilitation and exercise machine is provided which allows a person with physical limitations, disabilities or chronic conditions to use the machine in order to rehabilitate their muscles, improve joint flexibility, and enhance cardiovascular fitness.
Development Of Dehydrogenase-Based Bioanode Using Poly(Phenosafranin)-Functionalized Swcnt Nanocomposites And Its Application To Ethanol Biosensor,
2011
Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
Development Of Dehydrogenase-Based Bioanode Using Poly(Phenosafranin)-Functionalized Swcnt Nanocomposites And Its Application To Ethanol Biosensor, S. Saleh Farhana, Okajima Takeyoshi, Lanqun Mao, Takeo Ohsaka
Journal of Electrochemistry
A New type of dehydrogenase-based amperometric ethanol biosensor was constructed using alcohol dehydrogenase (ADH) which was immobilized on the edge-plane pyrolytic graphite (EPPG) electrode modified with poly(phenosafranin)-functionalized single-walled carbon nanotube (PPS-SWCNT). The PPS-SWCNT modified EPPG electrode was prepared by electropolymerization of phenosafranin on the EPPG electrode which was previously coated with SWCNT. The performance of the ADH/PPS-SWCNT/EPPG electrode was evaluated using cyclic voltammetry and amperometry in the presence of ethanol. The fabricated ethanol biosensor provided a reasonable sensitivity of 2.0 μA cm–2 mM–1 and a low detection limit (36 μM) for the electrocatalytic oxidation of ethanol with a linear concentration …
Study On The Fluorescent Carbon Nanodots With Electrochemical Methods,
2011
College of Chemistry and Molecular Seiences, Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), and Wuhan Institute of Biotechnology, Wuhan University, Wuhan 430072, China
Study On The Fluorescent Carbon Nanodots With Electrochemical Methods, Bao-Ping Qi, Yan-Min Long, Lei Bao, Cui Liu, Zhi-Ling Zhang, Dai-Wen Pang
Journal of Electrochemistry
Carbon nanodots are a new class of fluorescent nanoparticles with a carbon-based core, which possess wavelength-tunable luminescence, high photostability, resistance to photobleaching, water-solubility, and ease of bioconjugation. Owing to their attractive merits, carbon nanodots like other carbon nanomaterials such as fullerene, carbon nanotubes and graphene, have attracted much attention. In addition, carbon nanodots can be inexpensively produced by electrochemical methods with simple post-processing under mild conditions. Electrochemical approaches have unique advantages in the analysis of surface structures and luminescence mechanism of materials. In this review, recent advances in electrochemical methods used for the synthesis and luminescence mechanism of fluorescent carbon …
Study On The Electrochemical Behaviors Of Gc Electrode Modified With Carbon Nanotube-Polyelectrolytes And Its Application For Rutin Detection,
2011
Chemistry Department, Shanghai Normal University, Shanghai 200234, China
Study On The Electrochemical Behaviors Of Gc Electrode Modified With Carbon Nanotube-Polyelectrolytes And Its Application For Rutin Detection, Liang Hua, Xia-Qin Wu, Rong Wang
Journal of Electrochemistry
The electrochemical behaviors of rutin and ascorbic acid at single-wall carbon nanotube and polyelectrolytes (dimethyl-diallylammonium chloride, PDDA) film modified glassy carbon electrode was investigated. The cyclic voltammetric results showed that electron transfer of rutin at PDDA/SWCNTs/GC modified electrode is an adsorption-controlled process. The separation of oxidation peak potentials of rutin and ascorbic acid was more than 200 mV. The rutin concentration in the presence of AA were detected by differential pulse voltammetry (DPV). The experimental results indicated that the PDDA/SWCNTs/GC modified electrode can be used for the detection of rutin in the presence of high concentration of AA. The DPV …
Surface Diffusion Of Adsorptive Species On Gold Nanoelectrodes,
2011
State Key Laboratory of Physical Chemistry of Solid Surfaces, and Department of Chemistry, Collegeof Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
Surface Diffusion Of Adsorptive Species On Gold Nanoelectrodes, Bao-Fa Su, Wei Wang, Dong-Ping Zhan, Bin Ren, Zhong-Qun Tian
Journal of Electrochemistry
Gold nanoelectrodes were prepared successfully by a programmed laser puller. The Faraday adsorptions of oxygen and iodine, and the underpotential deposition of lead on the gold nanoelectrodes were investigated. The results showed that the active areas of nanoelectrodes were dramatically higher than their appearant geometry areas, which is caused by the surface diffusion of adsorptive species from the nanoscale gold/electrolyte interface to the adjacent gold surface.
