Search results for "electronics"

High Quality Factor Silicon Membrane Metasurface for Intensity-Based Refractive Index Sensing

2021

We propose a new sensing device based on all-optical nano-objects placed in a suspended periodic array. We demonstrate that the intensity-based sensing mechanism can measure environment refractive index change of the order of 1.8×10−6, which is close to record efficiencies in plasmonic devices.

Efficient Polymer Light‐Emitting Diode Using Air‐Stable Metal Oxides as Electrodes

2009

Poly(phenylenevinylene)‐based organic light‐emitting diodes (OLEDs) are fabricated using air‐stable metal oxides as electrodes, producing very efficient and bright electroluminescent devices. Efficiencies of 8 cd A−1 and luminances above 20000 cd m−2 are obtained, comparable to the values reported for classic OLED structures using reactive metals as cathodes.

Radiation-induced defects in antiferroelectric thin films

2003

Abstract Radiation effects on highly oriented antiferroelectric (AFE) PbZrO3 (PZ) films with a thickness of approximately 400 nm are investigated in view of their possible application as a temperature sensitive element in a new bolometer system for fusion devices like ITER. The films were prepared by pulsed laser deposition (PLD). The dielectric constant was measured in the frequency range from 1 to 250 kHz in a stepwise cooling mode (∼2 °C min−1) from 400 °C to room temperature before and after irradiation to a fast neutron fluence of 2×1022 m−2 (E>0.1 MeV). After irradiation, the films were annealed in several steps up to ∼400 °C to remove the radiation-induced defects. The results are di…

Combination of Confocal Raman Spectroscopy and Electron Microscopy on the Same Individual Bundles of Single-Walled Carbon Nanotubes

2002

We report a method to investigate the same individual single-walled carbon nanotube (SWNT) bundles with both transmission electron microscopy (TEM) and Raman spectroscopy. Free-standing individual bundles are obtained by depositing a solution of suspend SWNTs on a carbon film with a regular pattern of holes, which can be localized by TEM and also by confocal Raman microscopy. While most of the TEM images predict that the bundles consist of tubes with a similar diameter, we will show that occasionally a certain tube diameter can be associated with a particular radial breathing mode frequency of the Raman spectrum. Single-walled carbon nanotubes (SWNTs) are one-dimensional molecular structure…

Reconstruction Problem of Reinforced Concrete Beams under Harmonic Excitations

2007

A damage detection method based on harmonic structural vibrations has been applied to reconstruct realistic damage patterns of reinforced concrete beams. It was shown that the application of a hybrid method (genetic algorithm and Levenberg-Marquardt minimization technique) makes it possible to effectively reconstruct the flexural stiffness drops as small as 10-20% with the maximum error of 4%. The error increases to about 7 to 9% with the presence of 1% measurement noise.

Effect of driving method on the degradation of organic light emitting diodes

2003

Abstract Lifetime testing results are reported for organic light emitting diodes (OLEDs) having the structure ITO (anode)/ N , N ′-diphenyl- N , N ′-bis(3-methylphenyl)-1,1′-diphenyl-4,4′-diamine (TPD)/tris-(8-hydroxyquinoline)aluminum (AlQ)/Al (cathode) and operated using dc and pulsed waveforms for comparison. In ambient atmosphere non-encapsulated devices show a lifetime of about 70 h in pulsed operation at an initial luminance of 500 cd/m 2 , almost four times longer than in dc operation. A fast initial decay of luminance is observed for dc operation. It is most probably due to a combination of Joule heating and mobile ionic impurities migration within the OLED structure under the conti…

An Investigation of the Thermal Effects in Orthogonal Cutting Associated with Multilayer Coatings

2001

Abstract This paper deals with an experimental and analytical investigation into the tool-chip interface behaviour, influencing the temperature and heat transfer at the multilayered coated-tool rake face during orthogonal cutting of carbon and stainless steels. New methodology for assessing the amount of thermal energy generated when machining with a coated tool insert with natural and restricted contact coupled with a metallic chip, using thermophysical properties of the sliding materials is developed in this study. It was proven, based on the heat flux analysis, that the use of advanced coatings with an intermediate Al 2 O 3 layer can substantially improve the heat flow into the chip at d…

Model network architectures in vitro on extracellular recording systems using microcontact printing

2001

A PDMS stamp is used to transfer a synthetic peptide in a given pattern to any suitable surface. Using this method two-dimensional neuronal model networks could be formed on glass substrates as well as on electronic devices and adjusted to the given microelectronic structure. The present work focuses on the mechanism of neurite guidance under simplified in vitro conditions, using in vitro guidance cues and outline the incorporation of these interfacial methods into microelectronic sensor devices.

Oxygen-Induced Blinking of Single CdSe Nanocrystals

2001

A new gas sensor electronic interface with generalized impedance converter

2008

A new gas sensor conditioning circuit that allows a direct resistance-to-frequency conversion, as well as the procedure for the design, is presented. The generalized impedance converter (GIC) proposed is configured as a variable capacitor connected with the capacitor timing terminal of an astable multivibrator implemented by a PSoC (programmable system on chip) microcontroller device. The GIC effective input impedance, which is controlled by the gas sensor resistance, controls the astable output frequency. Good correlation of the experimental output frequency, which depends on the gas concentration, is achieved. The circuit is a simple gas sensor digital interface with frequency output.