Skin-Inspired Tactile Sensor on Cellulose Fiber Substrates with Interfacial Microstructure for Health Monitoring and Guitar Posture Feedback.

Skin-inspired flexible tactile sensors, with interfacial microstructure, are developed on cellulose fiber substrates for subtle pressure applications. Our device is made of two cellulose fiber substrates with conductive microscale structures, which emulate the randomly distributed spinosum in between the dermis and epidermis layers of the human skin. The microstructures not only permit a higher stress concentration at the tips but also generate electrical contact points and change contact resistance between the top and bottom substrates when the pressure is applied.

Au-Based Thin-Film Metallic Glasses for Propagating Surface Plasmon Resonance-Based Sensor Applications.

We deposited Au-Cu-Si, an Au-based thin-film metallic glass (TFMG) of ∼50 nm thickness, as the activation layer for propagating surface plasmon resonance (PSPR)-based sensors on a BK7 glass substrate to substitute the commonly used gold layer. The film composition was tuned to yield the maximum Au content (∼65 at %), while the structure remained amorphous. The results showed that the Au-based TFMG could support surface plasmon resonance and gave rise to the extinction in the angle-resolved reflection spectrum.

Structural and Optical Properties of Textured Silicon Substrates by Three-Step Chemical Etching.

We implemented the fabrication of hybrid structures, including pyramids, etching holes, and inverted pyramidal cavities on silicon substrates, by three-step chemical etching. To achieve this, we utilized anisotropic wet etching as the first-step etching to form pyramids of various sizes. Subsequently, metal-assisted chemical etching was performed to develop aligned etching holes on the pyramidal structure.

Effects of Al Addition on Microstructures and Mechanical Properties of CoCrFeMnNiAl High Entropy Alloy Films.

CoCrFeMnNiAl ( = 0, 0.07, 0.3, 0.

Surface plasmons excited by multiple layer grating.

The surface plasmons that are excited by the multiple layer grating structures on the gold thin film are studied using the finite-difference time-domain method in this paper. The structure parameters' effects on the coupling enhancement of surface plasmons are examined, and the structure design guidelines are given. It is found that the distance between the grating layers and the distance between the gratings and gold thin film are the key structure parameters for better cavity resonances.

Far-field and near-field monitoring of hybridized optical modes from Au nanoprisms suspended on a graphene/Si nanopillar array.

The optical hybridization of localized surface plasmons and photonic modes of dielectric nanostructures provides us wide arenas of opportunities for designing tunable nanophotonics with excellent spectral selectivity, signal enhancement, and light harvesting for many optical applications. Graphene-supported Au nanoprisms on a periodic Si nanopillar array will be an ideal model system for examining such an optical hybridization effect between plasmonic modes and photonic modes. Here, through the measurement of the reflectance spectra as well as graphene phonons by surface-enhanced Raman scattering (SERS), we investigated both the far-field and near-field properties of these optically hybridized modes.

Gold-rich ligament nanostructure by dealloying Au-based metallic glass ribbon for surface-enhanced Raman scattering.

A new method to fabricate an Au-rich interconnected ligament substrate by dealloying the Au-based metallic glass ribbon for surface-enhanced Raman scattering (SERS) applications was investigated in this study. Specifically, three substrates, Au film, Au-based metallic glass ribbon, and dealloyed Au-based metallic glass ribbon, were studied. The dealloyed surface showed ligament nanostructure with protruding micro-islands.

Effects of the rotation angle on surface plasmon coupling of nanoprisms.

We studied the effects of relative orientation of bowtie nanostructures on the plasmon resonance both experimentally and theoretically in this work. Specifically, we fabricated gold bowtie nanoantennas with rotated nanoprisms, measured the near-field and the far-field resonance behaviors using Raman spectroscopy and scattering microspectroscopy, and simulated the effects of the rotation angle on the localized surface plasmonic resonance using finite-difference time-domain simulations. In addition to the widely-discussed dipolar resonance in regular bowtie nanostructures, defined as tip-mode resonance in the present study, the excitations of edge-mode resonance were discovered under certain rotation angles of nanoprisms.

Electric field enhancement and far-field radiation pattern of the nanoantenna with concentric rings.

The optical antennas have the potential in various applications because of their field enhancement and directivity control. The directivity of a dipole antenna can be improved by directivity-enhanced Raman scattering structure, which is a combination of a dipole antenna and a ring reflector layer on a ground plane. The concentric rings can collect the light into the center hole.

Optical control of fluorescence through plasmonic eigenmode extinction.

We introduce the concept of optical control of the fluorescence yield of CdSe quantum dots through plasmon-induced structural changes in random semicontinuous nanostructured gold films. We demonstrate that the wavelength- and polarization dependent coupling between quantum dots and the semicontinuous films, and thus the fluorescent emission spectrum, can be controlled and significantly increased through the optical extinction of a selective band of eigenmodes in the films. This optical method of effecting controlled changes in the metal nanostructure allows for versatile functionality in a single sample and opens a pathway to in situ control over the fluorescence spectrum.

PRAP: an ab initio software package for automated genome-wide analysis of DNA repeats for prokaryotes.

Motivation: Prokaryotic genome annotation has been focused mainly on identifying all genes and their protein functions. However, <30% of the prokaryotic genomes submitted to GenBank contain partial repeat features of specific types and none of the genomes contain complete repeat annotations. Deciphering all repeats in DNA sequences is an important and open task in genome annotation and bioinformatics.

Resonance modes, cavity field enhancements, and long-range collective photonic effects in periodic bowtie nanostructures.

The discovery of single-molecule sensitivity via surface-enhanced Raman scattering on resonantly excited noble metal nanoparticles has brought an increasing interest in its applications to the molecule detection and identification. Periodic gold bowtie nanostructures have recently been shown to give a large enhancement factor sufficient for single molecule detection. In this work, we simulate the plasmon resonance for periodic gold bowtie nanostructures.

High tunability of the surface-enhanced Raman scattering response with a metal-multiferroic composite.

We demonstrate active control of the plasmonic response from Au nanostructures by the use of a novel multiferroic substrate-LuFe(2)O(4) (LFO)-to tune the surface-enhanced Raman scattering (SERS) response in real time. From both experiments and numerical simulations based on the finite-difference time-domain method, a threshold field is observed, above which the optical response of the metal nanostructure can be strongly altered through changes in the dielectric properties of LFO. This offers the potential of optimizing the SERS detection sensitivity in real time as well as the unique functionality of detecting multiple species of Raman active molecules with the same template.

Free-standing optical gold bowtie nanoantenna with variable gap size for enhanced Raman spectroscopy.

We describe plasmonic interactions in suspended gold bowtie nanoantenna leading to strong electromagnetic field (E) enhancements. Surface-enhanced Raman scattering (SERS) was used to demonstrate the performance of the nanoantenna. In addition to the well-known gap size dependence, up to 2 orders of magnitude additional enhancement is observed with elevated bowties.

Analyses of multilayered dental ceramics subjected to biaxial flexure tests.

Objectives: The purpose of this study was to formulate explicitly the equation to relate the biaxial strength of multilayered dental ceramics to the fracture load for multilayered discs subjected to biaxial flexure tests.

Methods: Analytical modeling showed that the solutions for multilayered discs subjected to biaxial flexure tests could be obtained from the existing solutions for monolayered systems by replacing the neutral surface position and the flexural rigidity of monolayers with those of multilayers. Finite element analyses were performed on porcelain/zirconia bilayered discs subjected to piston-on-ring and ring-on-ring tests to verify the analytical results.