Optoelectronic Platform Research Articles

Portable optoelectronic biosensing platform for identification of mycobacteria from the Mycobacterium tuberculosis complex

In this paper we report on the fabrication and performance of a portable and low cost optoelectronic platform integrating a double color tuned light emitting diode as light source, an amorphous/nanocrystalline silicon photodetector with a flat spectral response in the wavelength range from 520 nm to 630 nm and integrated electronic for signal acquisition and conditioning constituted by current to voltage converter, a filter and an amplification stage, followed by an analog to digital converter, with appropriate software for full automation to minimize human error. Incorporation of the double color tuned light emitting diode provides for a simple yet innovative solution to signal acquisition independently from the light intensity and/or solution concentration, while considerably decreasing production costs. Detection based on Au-nanoprobes constitutes the biorecognition step and allowed identification of specific sequences of Mycobacterium tuberculosis complex, namely Mycobacterium bovis and M. tuberculosis in biological samples.

Improvements in postural control through a dynamic balance training protocol in older overweight women

Background and Aims: Many studies have reported a greater frequency of falls among older women than men under conditions which stress balance. Previously, we have found an improvement in static balance in older women with an increased support surface area and an equal load redistribution on both feet in response to a dynamic balance training protocol. The aim of the present study was to examine whether the same training program and body composition would have effects on the postural control of older overweight women. Methods: Ten healthy women (68.67 ± 5.50 years; 28.17 ± 3.35 BMI) participated in a five-week physical activity program. This included dynamic balance exercises such as heel-to-toe walking in different directions, putting their hands on their hips, eyes open (EO) or closed (EC), with a tablet on the head, going up and down a step and walking on a mat. Postural stability was assessed before and after the training protocol with an optoelectronic platform and a uni-pedal balance performance test. Body composition of the trunk, upper limbs and lower limbs was measured by a bio-impedence analysis. Results: The mean speed (MS), medial-lateral MS (MS-x), anterior-posterior MS (MS-y), sway path (SP) and ellipse surface area (ESA) of the pressure centre was reduced in the older women after the training protocol. However, only MS; MS-x, MS-y and SP significantly decreased under bipodalic conditions with EO and MS-y also with EC (p Language: en

Theory of Superconductive Traveling-Wave Photodetectors

This paper studies the theory of traveling-wave photodetection in superconductive multilayer optical waveguides, as a general platform for ultrafast, ultrasensitive, and ultralow-noise optoelectronics. The kinetic inductance theory of superconductive thin films and the modified transmission line theory are employed to investigate the distributed photodetection and signal generation mechanisms in superconductive traveling-wave devices. A general model for calculation of the optical responsivity of superconductive traveling-wave photodetectors is developed and operation regimes of interest are highlighted. Moreover, the inclusion of a photoconductive layer in the device structure and some important loading schemes are discussed and their effects on the device performance, such as quantum efficiency and electrical bandwidth, are addressed.

Multi-functional SiC/Al Composites for Aerospace Applications

Multi-functional Al-matrix composites with high volume fraction (55%-57%) of SiC particles are produced with the new pres-sureless infiltration fabrication technology. X-ray detection and microscopic observation display the composites which are macroscopi-cally homogeneous without porosity. The investigation further reveals that the SiC/Al composites possess low density (2.94 g/cm3), high elastic modulus (220 GPa), prominent thermal management function as a result of low coefficient of thermal expansion (8×10−6 K−1) and high thermal conductivity (235 W/(m·K)) as well as unique preventability of resonance vibration. By adopting a series of developed techniques, the multi-functional SiC/Al composites have managed to be made into near-net-shape parts. Many kinds of precision components of space-based optomechanical structures and airborne optoelectronic platform have been turned out. Of them, several typical products are being under test in practices.

On-Chip Surface Plasmon Resonance Sensor

A novel on-chip micro SPR (surface plasmon resonance) sensor based on an optoelectronic platform has been developed. This research aims for a fully integrated SPR sensor system to achieve a miniaturized, high throughput sensor system. A novel method for design and fabrication of the solid state SPR sensor device has been investigated. The generation and detection of the SPR sensor signal from the proposed platform has been proved using a simulated binding experiment.

Identification of unamplified genomic DNA sequences using gold nanoparticle probes and a novel thin film photodetector

This paper describes a novel colorimetric method for detection of nucleic acid targets in a homogeneous format with improved sensitivity by means of a system based on the combination of a tunable monochromatic light source and an amorphous/nanocrystalline silicon photodetector that detects color and light intensity changes undergone by samples/assays containing tailored gold nanoparticles probes. This new low cost, portable, fast and simple optoelectronic platform, with the possibility to be re-used, permits detection of at least 400 fentomole of specific DNA sequences without target or signal amplification and was applied to the rapid detection of human pathogens in large variety of clinical samples such as Mycobacterium tuberculosis.

Characterization of optoelectronic platform using an amorphous/nanocrystalline silicon biosensor for the specific identification of nucleic acid sequences based on gold nanoparticle probes

Nanotechnology is having a positive impact on nearly every industry, and in particular in healthcare, where it is extending the limits of molecular diagnostics to the nanoscale—nanodiagnostics. Here we describe an innovative optoelectronic platform for the colorimetric detection of nucleic acids based on oligonucleotide-derivatized gold nanoparticles. The device integrates an amorphous/nanocrystalline biosensor and a light emission source with a gold nanoprobe for specific DNA detection. This low cost, fast and simple optoelectronic platform permits detection of few picomole of nucleic acid without target or signal amplification making it suitable for application in population diagnostics and in point-of-care hand-held devices.

Heteroepitaxy of AlGaN on bulk AlN substrates for deep ultraviolet light emitting diodes

The authors report the growth of AlGaN epilayers and deep ultraviolet (UV) light emitting diodes (LEDs) on bulk AlN substrates. Heteroepitaxial nucleation and strain relaxation are studied through controlled growth interruptions. Due to a low density of preexisting dislocations in bulk AlN, the compressive strain during AlGaN heteroepitaxy cannot be relieved effectively. The built-up of strain energy eventually induces either an elastic surface roughening or plastic deformation via generation and inclination of dislocations, depending on the stressor interlayers and growth parameters used. AlGaN LEDs on bulk AlN exhibit noticeable improvements in performance over those on sapphire, pointing to a promising substrate platform for III-nitride UV optoelectronics.

A novel method for fabrication of a hybrid optoelectronic packaging platform utilizing passive-active alignment

We present a novel fabrication method for a hybrid optoelectronic packaging platform using a combination of passive and active alignment. V-grooves on a silicon optical bench facilitate coarse passive alignment, while on-board thin-film heaters enable final active alignment. The passive-active alignment technique ensures /spl sim/50% peak-coupling efficiency from a semiconductor laser diode with a single-mode conically lensed fiber, making it a low-cost packaging solution appropriate for a variety of optoelectronic modules.

Design and fabrication of thin film resistive heaters for hybrid optoelectronic packaging

This paper presents the technology for the design and fabrication of planar resistive heaters made from vacuum deposited nichrome thin films on a quartz substrate. These heaters are suitable as isolated local heat sources for melting solder to attach discrete components on a hybrid optoelectronic integration platform. Numerical simulations are performed using the Finite Element Method (FEM) to determine the geometry of the heaters in order to deliver adequate thermal performance. Multiple heater elements are batch processed on a 3.0 in polished fused quartz wafer using standard photolithographic techniques. Use of polyimide as a reliable insulation layer between the nichrome thin film and the solder has improved the thermal uniformity over the heater surface. Individual heaters can reach temperatures close to 300/spl deg/C drawing 7.1 W of power on an uncooled alumina platform and 12.0 W on an uncooled copper platform. This temperature is high enough to melt gold-tin (AuSn) solder (with eutectic melting point of 280/spl deg/C), typically used for attaching different optoelectronic components on a substrate.

Energy transfer at optical frequencies to silicon-based waveguiding structures.

For decades, crystalline silicon (Si) has been the semiconductor of choice for the majority of applications in microelectronics. Recent advances in material science have focused attention on the silicon-on-insulator (SOI) platform, a submicrometer-thick layer of single crystal Si resting on an insulating silicon dioxide (SiO2) layer. Here we calculate the lifetime of an electric dipole moment oscillating in the cover region of several canonical Si waveguiding structures. We show that the vicinity just above SOI produces the most dramatic changes to the radiative lifetime and thus the power spectrum of the emitting dipole. We demonstrate that SOI stands apart from other Si-based optoelectronic platforms in its ability to transport energy, in the form of light, away from an oscillating electric dipole via highly localized, optical- and IR-frequency guided waves.

Applications of Silicon-Based Optoelectronics

Silicon-based optoelectronics is a diversified technology that has grown steadily but not exponentially over the past decade. Some applications—such as smart-pixel signal processing and chip-to-chip optical interconnects—have enjoyed impressive growth, whereas other applications have remained quiescent. A few important applications such as optical diagnosis of leaky metal-oxide-semiconductor-field-effect-transistor circuits, have appeared suddenly. Over the years, research and development has unveiled some unique and significant aspects of Si-based optoelectronics. The main limitation of this technology is the lack of practical silicon light sources—Si lasers and efficient Si light-emitting devices (LEDs)—though investigators are “getting close” to the LED.Silicon-based optoelectronics refers to the integration of photonic and electronic components on a Si chip or wafer. The photonics adds value to the electronics, and the electronics offers low-cost mass-production benefits. The electronics includes complementary-metal-oxide semiconductors (CMOS), very large-scale integration (VLSI), bipolar CMOS, SiGe/Si heterojunction bipolar transistors, and heterostructure field-effect transistors. In this discussion, we will use a loose definition of optoelectronics that includes photonic and optoelectronic integrated circuits (PICs and OEICs), Si optical benches, and micro-optoelectromechanical (MOEM) platforms. Optoelectronic chips and platforms are subsystems of computer systems, communication networks, etc. Silicon substrates feature a superior native oxide, in addition to excellent thermal, mechanical, and economic properties. Silicon wafers “shine” as substrates for PICs and OEICs.