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Improved optical enhancement using double-width plasmonic gratings with nanogaps

photonics Research 2016年第5期4卷 173-180页

作者： Ahmad A.Darweesh Stephen J.Bauman Joseph B.Herzog Microelectronics-Photonics Graduate Program University of Arkansas Department of Physics University of Arkansas

Plasmonic grating structures have been shown effective at increasing near-field optical enhancement. A doublewidth plasmonic grating design is introduced, where each period has two alternating metal widths separated by a nanogap. With this new design, analysis has shown that plasmonic resonances couple between each metal section,resulting in even greater optical enhancement compared with single-width gratings. The geometry that gives the greatest optical enhancement has been determined with a computational model. This work demonstrates that the increased enhancement is due to hybridized modes that couple between the two grating segments.

关键词： Improved optical enhancement using double-width plasmonic gratings with nanogaps nm

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Attribution of Fano resonant features to plasmonic particle size, lattice constant, and dielectric wavenumber in square nanoparticle lattices

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photonics Research 2014年第1期2卷 15-23页

作者： Drew DeJarnette Justin Norman D.Keith Roper Microelectronics and Photonics Graduate Program University of ArkansasFayettevilleArkansas 72701USA Department of Chemical Engineering University of ArkansasFayettevilleArkansas 72701USA

Fano resonances between plasmons and diffracted light offer tunable energies and locales,but attribution of Fano resonance features to geometry and physicochemistry of metal nanostructures and adjacent dielectrics has been confounded by complexity and computational *** work shows predictable modal shifts of Fano resonance in square lattices of plasmonic nanostructures can be attributed directly to changes in medium wavenumber,particle size,and lattice constant that alter plasmon polarizability and diffractive *** 45 to 80 nm radius particles,a window of lattice constants that support Fano resonances is identified in a range from 500 to 900 *** constants that support high intensity resonances are determined by individual particle polarizability and medium *** resonance wavelengths redshift from diffracted photon energies as local refractive index(RI)changes due to coupling with particle polarizability in the *** sensitivities for quadrupole,dipole,and Fano resonances are 150,348,and 541 nm,respectively,per RI *** resonance intensity may be enhanced more than tenfold by selecting nanoparticle sizes and lattice *** quantitative effects of such parametric changes are rapidly and intuitively distinguished using a semi-analytic approach,consisting of an exact expression for particle polarizability,a trigonometric description of diffraction,and a semianalytical coupled dipole approximation.

关键词： lattice particle wave

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An enzymatic glucose detection sensor using ZnO nanostructure

An enzymatic glucose detection sensor using ZnO nanostructur...

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作者： Marie, Mohammed Mandal, Sanghamitra Manasreh, Omar Microelectronics and Photonics Graduate Program University of Arkansas FayettevilleAR72701 United States Department of Electrical Engineering University of Arkansas FayettevilleAR72701 United States

Glucose sensor based on ITO/ZnO NRs/GOx/nafion is fabricated and tested under different glucose concentrations. Hydrothermal growth method along with sol-gel technique is used to grow high quality ZnO nanorods that have well-alignment and high density with an acceptable aspect ratio. The as-grown of ZnO nanorods are used to fabricate a working electrode that can be used for glucose detection in blood after a modification process with GOx and nafion membrane. Annealing at 110°C helped in improves the crystallinity of the seed layer and as a result, a high density and well alignment as-grown ZnO nanorods were obtained. High sensitivity and short response time were obtained from the fabricated device with an acceptable lower limit of detection. © Copyright Materials Research Society 2016.

关键词： Sol-gels

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Anomalous, non-Gaussian, viscoelastic, and age-dependent dynamics of histonelike nucleoid-structuring proteins in live Escherichia coli

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Physical Review E 2018年第4期98卷 042411-042411页

作者： Asmaa A. Sadoon Yong Wang Department of Physics Microelectronics-Photonics Graduate Program Cell and Molecular Biology Program University of Arkansas Fayetteville Arkansas 72701 USA

We report our measurements of the dynamics of histonelike nucleoid-structuring (H-NS) proteins, which interact with both proteins and DNA simultaneously, in live Escherichia coli bacteria. The dynamics turn out to differ significantly from other molecules reported previously. A power-law distribution was observed for the diffusion coefficients of individual H-NS proteins. In addition, we observed a distribution of displacements which does not follow the Gaussian, Cauchy, or Laplace distributions but the Pearson Type VII distribution. Furthermore, we experimentally measured the time and frequency dependence of the complex modulus of the bacterial cytoplasm, which deviates from the viscoelasticity of homogeneous protein solutions and shows a glass-liquid transition. Last, we observed that the dynamics of H-NS proteins is cell length and cell age dependent. The findings are expected to fundamentally change the current views on bacterial cytoplasm and diffusional dynamics of molecules in bacteria.

关键词： Anomalous diffusion Viscoelasticity

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Electromechanical properties of one dimensinal carbon chains 9

Electromechanical properties of one dimensinal carbon chains

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9th IEEE International Conference on Nano/Molecular Medicine and Engineering, NANOMED 2015

作者： Salman, Zeina Nair, Arun Tung, Steve Microelectronics and Photonics Graduate Program University of Arkansas FayettevilleAR72701 United States Department of Mechanical Engineering University of Arkansas FayettevilleAR72701 United States

ISBN: (纸本)9781467396714

Carbon based nanostructures such as graphene and carbon nanotubes have received widespread attention due to their unique mechanical and electronic properties. This paper describes a quantum mechanics based study of the electronic band structures and transport properties of one-dimensional (1D) carbon chains, the thinnest nanowires available in nature. The study is based on the application of density functional theory and non-equilibrium Green's function where maximally localized Wannier functions and Landauer formalism are combined to compute the electronic band structures and quantum conductance of the 1D carbon chains. The simulation result indicates that the peak quantum conductance of 1D carbon chains is about five times smaller than that of carbon nanotubes. However, the quantum conductance is also a function of the length and chemical bonds of the carbon chains. When the carbon chains are mechanically strained at 3%, the quantum conductance is reduced by about 50%. This result suggests 1D carbon chains can provide ultra high-resolution electromechanical measurements of important biomolecules such as DNA. © 2015 IEEE.

关键词： Carbon nanotubes

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Plasmon optics and thermal dissipation in nanocomposite thin films

Plasmon optics and thermal dissipation in nanocomposite thin...

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2015 MRS Spring Meeting

作者： Dunklin, Jeremy R. Forcherio, Gregory T. Berry, Keith R. Roper, D.K. Department of Chemical Engineering University of Arkansas FayettevilleAR72701 United States MicroElectronics-Photonics Graduate Program University of Arkansas FayettevilleAR72701 United States

ISBN: (纸本)9781510826427

Optical properties and thermal relaxation dynamics of resonantly excited plasmons are important in applications for optoelectronics, biomedicine, energy, and catalysis. Geometric optics of polydimethylsiloxane (PDMS) thin films containing uniformly or asymmetrically distributed polydisperse reduced AuNPs or uniformly distributed monodisperse solution-synthesized AuNPs were recently evaluated using a compact linear algebraic sum. Algebraic calculation of geometric transmission, reflection, and attenuation for AuNP-PDMS films provides a simple, workable alternative to effective medium approximations, computationally expensive methods, and fitting of experimental data. This approach allows for the summative optical responses of a sequence of 2D elements comprising a 3D assembly to be analyzed Thin PDMS films containing 3-7 micron layers of reduced AuNPs were fabricated with a novel diffusive-reduction synthesis technique. Rapid diffusive reduction of AuNPs into asymmetric PDMS thin films provided superior photothermal response relative to thicker films with AuNPs reduced throughout, with a photon-to-heat conversion of up to 3000°C/watt which represents 3-230-fold increase over previous AuNP-functionalized systems. Later work showed that introduction of AuNPs into PDMS enhanced thermoplasmonic dissipation coincident with internal reflection of incident resonant irradiation. Measured thermal emission and dynamics of AuNP-PDMS thin films exceeded emission and dynamics attributable by finite element analysis to Mie absorption, Fourier heat conduction, Rayleigh convection, and Stefan-Boltzmann radiation. Refractive-index matching experiments and measured temperature profiles indicated AuNP-containing thin films internally reflected light and dissipated power transverse to the film surface. Enhanced thermoplasmonic dissipation from metal-polymer nanocomposite thin films could affect opto- and bio-electronic implementation of these systems. © 2015 Materials Research Society.

关键词： Thin films

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Mechanical-energy-based amplifiers for probing interactions of DNA with metal ions

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Physical Review E 2018年第6期98卷 062403-062403页

作者： Jack Freeland Prabhat Khadka Yong Wang Department of Physics Microelectronics-Photonics Graduate Program Cell and Molecular Biology Program University of Arkansas Fayetteville Arkansas 72701 USA

We report our development of a simple and cost-effective method to amplify and probe the interactions of DNA with metal ions, which are important for various fundamental processes in living systems. This method is based on perturbing energy landscapes using mechanical energy stored in bent DNA molecules. In this proof-of-principle study, the mechanical-energy-based amplifiers were applied to examine the interactions between DNA and Mg2+ ions or Ag+ ions. We demonstrated that interactions between DNA and Mg2+ or Ag+ ions, which are not detectable using gel electrophoresis without amplification, can be easily measured using our molecular amplifiers. In addition, we showed that quantitative details about the DNA-metal interactions can be estimated using our method. Our method is simple, sensitive, and cost-effective. We expect that the developed method will be useful for various applications.

关键词： Biomechanics DNA

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Plasmon optics and thermal dissipation in nanocomposite thin films

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MRS Online Proceedings Library (OPL) 2015年第1期1788卷 23-28页

作者： Jeremy R. Dunklin Gregory T. Forcherio Keith R. Berry Jr. D.K. Roper Department of Chemical Engineering University of Arkansas Fayetteville AR 72701 MicroElectronics-Photonics Graduate Program University of Arkansas Fayetteville AR 72701

Optical properties and thermal relaxation dynamics of resonantly excited plasmons are important in applications for optoelectronics, biomedicine, energy, and catalysis. Geometric optics of polydimethylsiloxane (PDMS) thin films containing uniformly or asymmetrically distributed polydisperse reduced AuNPs or uniformly distributed monodisperse solution-synthesized AuNPs were recently evaluated using a compact linear algebraic sum. Algebraic calculation of geometric transmission, reflection, and attenuation for AuNP-PDMS films provides a simple, workable alternative to effective medium approximations, computationally expensive methods, and fitting of experimental data. This approach allows for the summative optical responses of a sequence of 2D elements comprising a 3D assembly to be analyzed. Thin PDMS films containing 3-7 micron layers of reduced AuNPs were fabricated with a novel diffusive-reduction synthesis technique. Rapid diffusive reduction of AuNPs into asymmetric PDMS thin films provided superior photothermal response relative to thicker films with AuNPs reduced throughout, with a photon-to-heat conversion of up to 3000°C/watt which represents 3-230-fold increase over previous AuNP-functionalized systems. Later work showed that introduction of AuNPs into PDMS enhanced thermoplasmonic dissipation coincident with internal reflection of incident resonant irradiation. Measured thermal emission and dynamics of AuNP-PDMS thin films exceeded emission and dynamics attributable by finite element analysis to Mie absorption, Fourier heat conduction, Rayleigh convection, and Stefan-Boltzmann radiation. Refractive-index matching experiments and measured temperature profiles indicated AuNP-containing thin films internally reflected light and dissipated power transverse to the film surface. Enhanced thermoplasmonic dissipation from metal-polymer nanocomposite thin films could affect opto- and bio-electronic implementation of these systems.

关键词： polymer Au film

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Creating an industrial work group atmosphere in technology graduate programs: An unexpected impact on minority success in graduate school

Creating an industrial work group atmosphere in technology g...

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113th Annual ASEE Conference and Exposition, 2006

作者： Vickers, Ken Foster, Ron Salamo, Greg University of Arkansas United States Department of Physics University of Arkansas United States Interdisciplinary Microelectronics-Photonics Graduate Program Basore Endowed Department of Physics University of Arkansas United States Optical Society of America United States

The interdisciplinary graduate program in microelectronics-photonics (microEP) was created at the University of Arkansas in the fall of 1998 to merge traditional graduate research and educational excellence with specific training in operational effectiveness methods, intra and entrepreneurial skills, and teaming and group dynamics practice. The stated goal of this approach was to create a graduate program that emulates the industrial work group environment, with the group objective being that every graduate student achieves the highest academic training of which he or she is capable. In the seven years since the microEP grad program was started, this educational experiment in creating a graduate program centered in a natural work group culture has proven beneficial to its students - and has even been largely adopted by the UA Physics graduate program1. What was not expected is that this natural work group approach also created a graduate community that has acted to bridge minority students from the heavily supportive MSI atmosphere to the generally impersonal atmosphere found in white majority research intensive grad programs. Including the fall 2005 entering microEP Cohort 8 students, one hundred and three students are currently enrolled or graduated. This includes seventeen minority students, a percentage half again as high as the national average of graduating minority PhD students2and much higher than the current enrollment in the traditional UA science and engineering graduate programs. Two African-American men have completed their PhD microEP degrees, with one joining Virginia Commonwealth University as a tenure track faculty member, and the second currently enrolled in the University of Alabama Birmingham Medical School. In this paper the authors will first discuss methods that have been used to locate students in communities underrepresented in science and engineering that would be well served by the microEP research and educational training. The authors wil

关键词： Engineering education

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AFM based Topography Characterization of Smooth, Nanotextured, and Microtextured Surfaces

AFM based Topography Characterization of Smooth, Nanotexture...

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IEEE International Conference on Micro/Nano Sensors for AI, Healthcare, and Robotics

作者： Uchechukwu C. Wejinya Guangyi Shi Abayomi Omolewu Department of Mechanical Engineering University of Arkansas Peking University Shenzhen Graduate School Microelectronics-Photonics Graduate Program University of Arkansas

ISBN: (纸本)9781538694091;9781538694084

Surface topography is important to the function of many kinds of industrial products and is constantly growing with the increase advancement of technology. It is important to understand surface topography measurement and how to control it effectively. Surface roughness is an important parameter of topography characterization and is quantified by the vertical deviations of a real surface from its ideal form. Therefore, depending on the application it may be desirable to have either a rough surface or a very smooth surface. Rough surfaces can be desirable for cell adhesion and plays a great role in biological or biomedical application. Smooth surfaces can be desirable in applications where there are two interacting surfaces and minimal wear between the two is needed. This work addresses the surface topography characterizing of a smooth, nanotextured, and microtextured surface.

关键词： Rough surfaces Surface roughness Surface topography Surface texture Surface treatment Response surface methodology

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