Superior Antireflection Coating for a Silicon Cell with a Micronanohybrid Structure

The object of this paper is to develop a high antireflection silicon solar cell. A novel two-stage metal-assisted etching (MAE) method is proposed for the fabrication of an antireflective layer of a micronanohybrid structure array. The processing time for the etching on an N-type high-resistance (NH) silicon wafer can be controlled to around 5 min. The resulting micronanohybrid structure array can achieve an average reflectivity of 1.21% for a light spectrum of 200–1000 nm. A P-N junction on the fabricated micronanohybrid structure array is formed using a low-cost liquid diffusion source. A high antireflection silicon solar cell with an average efficiency of 13.1% can be achieved. Compared with a conventional pyramid structure solar cell, the shorted circuit current of the proposed solar cell is increased by 73%. The major advantage of the two-stage MAE process is that a high antireflective silicon substrate can be fabricated cost-effectively in a relatively short time. The proposed method is feasible for the mass production of low-cost solar cells

A Novel Contact Resistance Model of Anisotropic Conductive Film for FPD Packaging

In this research, a novel contact resistance model for the flat panel display (FPD) packaging based on the within layer parallel and between layers series resistance concepts was proposed. The FJ2530 anisotropic conductive films (ACF) by Sony Inc. containing the currently smallest 3micron conductive particles was used to conduct the experiments to verify the accuracy of the proposed model. Calculated resistance of the chip-on-glass (COG) packaging by the proposed model is 0.163\Omega. It is found that the gold bump with 0.162\Omega resistance play the major role of the overall resistance. Although the predicted resistance by the proposed model is only one third of the experimentally measured value, it has been three-fold improvement compared to the existing models.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

A NOVEL CHLOROPLASTMIMIC PHOTOVOLTAICS WITH FULL VISIBLE SPECTRUM OPERATION

ABSTRACT A novel and very simple chloroplastmimic photovoltaic scheme, in which water is photolyzed by a new photocatalyst fabricated by depositing a thin film of TiO 2 on an array of carbon nanotubes (CNT), has been made. Multiple reflections within the photocatalyst extend the optical response from the ultraviolet range to the full visible range. Hydrogen ions with various concentrations are separated by an artificial thylakoid membrane, resulting in a transmembrane chemiosmotic potential, generating ion-diffusion-induced electricity. Experimental results demonstrate that the proposed simple chloroplastmimic photovoltaics can produce a photocurrent directly from visible light. 1 INTRODUCTION Chloroplasts are regarded as the most effective energy conversion plants of sunlight. Chloroplasts seize the energy of sunlight to produce the free energy stored in adenosine 5'-triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADP) via photosynthesis. Photosynthesis is an important biochemical process in which plants transform light energy from the sun into chemical energy. During photosynthesis, the ATP is synthesized by an ATP synthase enzyme by using the chemiosmotic potential across the thylakoid membranes of the chloroplasts. The hydrogen ions that are formed by the products of the photolysis of water by chlorophyll contribute to the transmembrane chemiosmotic potential. The rate at which solar radiation reaches the earth's surface is 1,020 W/m². For centuries, human beings have attempted to mimic the conversion mechanisms of chloroplasts by harnessing the energy of sunlight. The conversion mechanism of the chloroplast represents a promising new energy resource. Conventional solar cells exploit the photovoltaic effect of semiconductors to produce electricity directly from sunlight. Despite the great major progress made over the last decade, the use of silicon-based solar cells remains more expensive than traditional electricity generation. One promising approach for reducing costs even further involves dye-sensitized solar cells (DSSC) [1-4] that photosensitize wide-band-gap mesoporous oxide semiconductors. Michael Graetzel et al. 1 developed DSSC in 1991. The structure of a DSSC comprises of two electrodes and an electrolyte that contains iodide. One electrode is dye-absorbed nanoporous titanium dioxide (TiO 2 ) that is deposited on a transparent electrically conducting substrate -usually made of indium tin oxide (ITO). The other is only a transparent electrically conducting substrate. When sunlight passes through ITO, any dyes adsorbed on it are photo-excited. One of the electrons in the dye jumps from the valence band to the conduction band in TiO 2 . The electron then diffuses across the porous film of TiO 2 , arriving at ITO, and through the iodidecontaining electrolyte, returning the oxidized dye molecules to their initial state. Since the DSSC uses the redox reaction of the electrolyte, it has been compared to the photosynthesis of chloroplasts. The performance of DSSC can be further improved using TiO 2 nanotube arrays, as demonstrated by recent works that water can be split using carbon-doped TiO 2 nanotube array

Electrochemical impedimetric biosensor based on a nanostructured polycarbonate substrate

This study integrates the techniques of nanoelectroforming, hot-embossing, and electrochemical deposition to develop a disposable, low-cost, and high sensitivity nanostructure biosensor. A modified anodic aluminum oxide barrier-layer surface was used as the template for thin nickel film deposition. After etching the anodic aluminum oxide template off, a three-dimensional mold of the concave nanostructure array was created. The fabricated three-dimensional nickel mold was further used for replica molding of a nanostructure polycarbonate substrate by hot-embossing. A thin gold film was then sputtered onto the polycarbonate substrate to form the electrode, followed by deposition of an orderly and uniform gold nanoparticle layer on the three-dimensional gold electrode using electrochemical deposition. Finally, silver nanoparticles were deposited on the uniformly deposited gold nanoparticles to enhance the conductivity of the sensor. Electrochemical impedance spectroscopy analysis was then used to detect the concentration of the target element. The sensitivity of the proposed scheme on the detection of the dust mite antigen, Der p2, reached 0.1 pg/mL

Fabrication of Nanostructured PLGA Scaffolds Using Anodic Aluminum Oxide Templates

PLGA (poly(lactic-co-glycolic acid)) is one of the most used biodegradable and biocompatible materials. Nanostructured PLGA even has great application potentials in tissue engineering. In this research, a fabrication technique for nanostructured PLGA membrane was investigated and developed. In this novel fabrication approach, an anodic aluminum oxide (AAO) film was use as the template ; the PLGA solution was then cast on it ; the vacuum air-extraction process was applied to transfer the nano porous pattern from the AAO membrane to the PLGA membrane and form nanostures on it. The cell culture experiments of the bovine endothelial cells demonstrated that the nanostructured PLGA membrane can double the cell growing rate. Compared to the conventional chemical-etching process, the physical fabrication method proposed in this research not only is simpler but also does not alter the characteristics of the PLGA. The nanostructure of the PLGA membrane can be well controlled by the AAO temperate.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838

Sb 2

We propose a novel quantum-dot sensitized solar cell (QDSSC) structure that employs a quantum dot/semiconductor silicon (QD/Si) coaxial nanorod array to replace the conventional dye/TiO2/TCO photoelectrode. We replaced the backlight input mode with top-side illumination and used a quantum dot to replace dye as the light-absorbing material. Photon-excited photoelectrons can be effectively transported to each silicon nanorod and conveyed to the counter electrode. We use two-stage metal-assisted etching (MAE) to fabricate the micro-nano hybrid structure on a silicon substrate. We then use the chemical bath deposition (CBD) method to synthesize a Sb2S3 quantum dot on the surface of each silicon nanorod to form the photoelectrode for the quantum dot/semiconductor silicon coaxial nanorod array. We use a xenon lamp to simulate AM 1.5 G (1000 W/m2) sunlight. Then, we investigate the influence of different silicon nanorod arrays and CBD deposition times on the photoelectric conversion efficiency. When an NH (N-type with high resistance) silicon substrate is used, the QD/Si coaxial nanorod array synthesized by three runs of Sb2S3 deposition shows the highest photoelectric conversion efficiency of 0.253%. The corresponding short-circuit current density, open-circuit voltage, and fill factor are 5.19 mA/cm2, 0.24 V, and 20.33%, respectively

DESIGN AND FABRICATION OF A HIGH EFFICIENCY PIEZOELECTRIC VIBRATION-INDUCED MICRO POWER GENERATOR

ABSTRACT To fulfill the increasing self-power demanding of the embedded and remote microsystems, theoretical and experimental study of a piezoelectric vibration-induced micro power generator that can convert mechanical vibration energy into electrical energy is presented. A complete energy conversion model regarding the piezoelectric transducer is discussed first. To verify the theoretical analysis, two clusters of transducer structures are fabricated. The piezoelectric lead zirconate titanate (PZT) material that has better energy conversion efficiency among the piezoelectric materials is chosen to make of the energy conversion transducer. The desired shape of the piezoelectric generator with its resonance frequency in accordance with the ambient vibration source is designed by finite element analysis (FEA) approach. Conducting wires and load resistor are soldered on the electrodes to output and measure the vibration induced electrical power. Experimental results shows that the maximum output voltages are generated at the first mode resonance frequencies of the structure. It is also found from the experimental results that the induced voltage is irrelevant to the width of the structure but is inverse proportion to the length of the structure. It takes 7 minutes to charge a 10,000 µF capacitors array to a 7 V level. The total amount of electricity and energy stored in the capacitors are 0.7 Coulomb and 0.245 J, respectively. The experimental results are coincidence with the theoretical analysis

Special Issue on “MEMS/NEMS Fabricated Tissue Scaffolding Devices”

Over the past decade, tissue engineering in the field of medicine has proven to provide alternative therapies for tissue or organ implants, especially providing a functional implantation and avoiding immune rejection of tissues and organs. [...

A Glucose Biosensor Based on a 3D Nanostructured Gold Electrode

In this study, we investigated a simple glucose biosensor based on a 3D nanostructured gold electrode. The nanostructured goldelectrode was fabricated by electrochemical deposition using bulk gold dissolved in aqua regia as the nanogold precursor. Potassiumferricyanide and glucose oxidase were then sequentially coated onto the prepared nanostructure for glucose detection. For thenanostructured electrode, the polarization overpotential for glucose detection was 0.17 V, which is much smaller than that for a planeelectrode. An applied potential of 0.7 V was sufficient to generate peak cathodic currents. The peak cathodic and anodic currents forthe nanostructured electrode are three orders of magnitude larger than those for a plane gold electrode. The nanostructured electrodeshows a fast response time of 1 s

Highly sensitive glucose biosensor based on Au–Ni coaxial nanorod array having high aspect ratio

An effective glucose biosensor requires a sufficient amount of GOx immobilizing on the electrode surface. An electrode of a 3D nanorod array, having a larger surface-to-volume ratio than a 2D nanostructure, can accommodate more GOx molecules to immobilize onto the surface of the nanorods. In this study, a highly sensitive Au-Ni coaxial nanorod array electrode fabricated through the integration of nano electroforming and immersion gold (IG) method for glucose detection was developed. The average diameter of the as-synthesized Ni nanorods and that of the Au-Ni nanorods were estimated to be 150 and 250 nm, respectively; both had a height of 30 μm. The aspect ratio was 120. Compared to that of a flat Au electrode, the effective sensing area was enhanced by 79.8 folds. Actual glucose detections demonstrated that the proposed Au-Ni coaxial nanorod array electrode could operate in a linear range of 27.5 μM-27.5mM with a detection limit of 5.5μM and a very high sensitivity of 769.6 μA mM(-1)cm(-2). Good selectivity of the proposed sensing device was verified by sequential injections of uric acid (UA) and ascorbic acid (AA). Long-term stability was examined through successive detections over a period of 30 days