Добірка наукової літератури з теми "Anodized Aluminium Oxide Template (AAOT)"

The Self-Organizing Anodic Aluminium Oxide(AAO) Template Is Widely Used to Construct the Nanomaterials. but the AAO Film Is Very Thin and Brittle, the AAO Templates Are Easily Been Destroied when Widening and Opening the Nanopores. the Nanorods/wires Constructed by this Template Likely Aggregate because of the High Activity of Nano-Surface at Short Range. this Paper Proposed a Novel Image of AAO Template in which Several Nanopores Combined Together to Form a Large Open Holes without Widening the Cells and Opening Barrier Layers. the Electronic Aluminium Foils with 99.99% Purity Is Anodized in Phosphoric Acid by Two-Steps, then Polarized under a Negative Voltage in the Kcl Solution. the Result of Experiment Demostrated the Possibility of the Formation Mechanism of this New Templates.

The use of anodized aluminum oxide (AAO) is vastly being explored in recent years. The application includes molecular separation, sensing, energy storage and template synthesis for various nanostructures. The reason AAO is preferred was because of the ability to control the nanopore structure by manipulating some factors during the anodisation process. This study will investigate the exploitation of voltage and anodisation time during the anodisation process and the effect it has on the nanopore structure of the AAO by examining the structure under Field Emission Scanning Electron Microscope (FE-SEM). The experiment was carried out by anodizing aluminum foil in 0.3 M oxalic acid as electrolyte under the constant temperature of 5 °C. The applied voltage was varied from 40, 60 and 100 V with different anodisation time. The outcome of this study demonstrates that applied voltage has a proportional relationship with the developed pore size. Increasing the applied voltage from 40 to 100 V had increased the pore size of the AAO from 38 nm to 186 nm, respectively. Aluminium oxide anodized at 60 V demonstrates pore size in the range of 76 nm. Prolong anodisation time had improved the pore morphology of anodized aluminium oxide in the case of 40 V, however, the pore wall starts to collapse when anodisation time is more than 4 minutes at 100 V.

The feasibility of surface nanopatterning with TiO2nanotanks embedded in a nanoporous alumina template was investigated. Self-assembled anodized aluminium oxide (AAO) template, in conjunction with sol gel process, was used to fabricate this nanocomposite object. Through hydrolysis and condensation of the titanium alkoxide, an inorganic TiO2gel was moulded within the nanopore cavities of the alumina template. The nanocomposite object underwent two thermal treatments to stabilize and crystallize the TiO2. The morphology of the nanocomposite object was characterized by Field Emission Scanning Electron Microscopy (FESEM). The TiO2nanotanks obtained have cylindrical shapes and are approximately 69 nm in diameter with a tank-to-tank distance of 26 nm. X-ray diffraction analyses performed by Transmission Electron Microscopy (TEM) with selected area electron diffraction (SAED) were used to investigate the TiO2structure. The optical properties were studied using UV-Vis spectroscopy.

Purpose This paper aims to study the anodization of aluminum in a mixture solution of 1,3-propanediol solutions and 0.4 mol l−1 H3PO4 at a low temperature. Design/methodology/approach The morphology and composition of the resulting anodic aluminum oxide (AAO) template was characterized by means of a scanning electron microscope in combination with an energy dispersive spectrometer. Findings Pore density and pore diameter both were found to be dependent on the temperature of anodization. Originality/value The resulting AAO templates exhibited uniform and regular pores with diameters that were significantly smaller than those found in AAO templates anodized at room temperature.

In this paper, we review recent advances in nanotemplate fabrication using anodized aluminum oxide (AAO). In addition to self-ordered AAO nanoarrays, guided AAO self-assembly is of great interest since it can offer highly ordered, vertically aligned nanoporous templates which are suitable for various materials synthesis and alignment of nanosized structures. Moreover, structural modification of AAO nanoarrays by controlling fabrication process parameters are reviewed which can be applicable for advanced micro- and nanosystems. In this aspect, potential applications using AAO will be revealed in the aspects of self-ordered AAO, guided self-assembly of AAO, and biomedical and magnetic applications.

Surface Enhanced Raman Spectroscopy (SERS) has become a powerful method for detection of diverse analytes ranging from solution of picomolar concentration to single molecule and single cell analysis. The distinctive nature of SERS technique comes from the resonance of surface plasmons of metal nanostructure due to oscillating electric field of the incident laser. Surface plasmon resonance results in enhanced electric field or hotspots in the vicinity of metal structure which results in amplified Raman signal. Optimum hotspots on SERS substrate are achieved by fabricating appropriate metal nanostructures. Efficacy of the nanostructures depends on efficient excitation of plasmon resonance and interaction of the plasmons with its adjacent environment. Hence, substrate with favorable optical property would aid in pushing the limits of detection. Recent development in biosensors for qualitative and quantitative detection using SERS technique involves precise engineering in fabrication of SERS substrates. The requirement of a fixed SERS platform, instead of conventional metal nanoparticle colloid, is preferred in a Lab-on-a-chip (LOC) system. This thesis focuses on exploring substrate effects on surface plasmon resonance of metal nanostructure. In the process, large area SERS substrates have been fabricated for detection of various analytes. One of such substrates has been integrated with centrifugal microfluidic (CMF) system. In this work, plasmon-substrate interaction has been studied elaborately using analytical models and computational tools. Silver nanoparticles have been fabricated on Si substrate by sputtering. Optical properties of the substrate have been modified by depositing SiO2, HfO2 and Si3N4 films of varying thickness. Non-radiative and radiative interactions have been observed prominently in SERS spectra which correlate with the optical property of the substrate. The most effective interaction has been the energy transfer between the plasmons and the polarization charges of the base Si substrate. These serve as guidelines to fabricate, modify and improve large area SERS substrates. Anodized Aluminum Oxide Template (AAOT) and Germanium Nanowire (GeNW) have been fabricated and subsequently coated with thin silver film for application in SERS as large area substrate. Anodization of Al thin film has been studied with varying fabrication parameters. Resulting nanopores have been coated with Ag and the evolution of silver film on the template has been observed. Optimized Ag structures show enhanced performance depending on the location of the hotspots on these substrates. Extensive experiments have been carried out to understand vapour-liquid-solid (VLS) growth of Si and Ge nanowires using plasma enhanced chemical vapour deposition (PECVD) technique with precise control over the length of the NWs. GeNWs with dielectric shell were coated with Ag film and AgNPs. Subsequently, the efficacy of the SERS substrates was compared. Aforementioned plasmon-substrate interactions have been observed in the characterization results of the large area substrates. However, tuning of these substrates for a specific wavelength is extremely complex. This brings the requirement of an ideal substrate possessing the following properties: i. Scalable fabrication process ii. Ease of tunability for any wavelength iii. High shelf life Hence, silver nano-buds have been fabricated to address the issues. Silver structures are fabricated on the tip of GeNWs through galvanic displacement reaction. An optimization technique has been developed to tune the substrate to any wavelength in real time. The analytical enhancement factors remain close to 105 for a wide range of wavelengths which is comparable to some of substrates fabricated by e-beam lithography. GeNW substrates do not require any specific packaging and silver can be formed easily on the substrates on demand. This substrate also addresses the most important issue of shelf life. Ag nano-bud substrate has been subsequently used in an integrated SERS microfluidic system for analysis of blood components. Centrifugal microfluidic (CMF) devices have been developed for plasma and cell separation from whole blood. A valving mechanism was developed to manipulate fluid flow on the same CMF disc which enables integration of multiple microfluidic networks. Later, soft lithography process has been modified to incorporate silver nano-bud SERS substrate in the CMF disc. Thus, a complete integrated CMF-SERS device has been fabricated. This does not require fabrication of SERS active site either on PDMS or on glass. Prefabricated SERS substrate has been used to accomplish this which has drastically reduced the process steps and complexity as compared to other methods reported in literature. As a proof-of-concept, SERS substrate has been integrated with plasma separation device and SERS spectrum has been obtained for plasma.

In this work, the interaction between the size effect and the thermomechanically induced phase transformation for SMAs composed of Indium-Thallium (InTl) is analyzed. An In-21at%Tl alloy is first fabricated, from which In-21at%Tl nanowires are subsequently produced. Using the mechanical pressure injection system, the bulk alloy is pressed into pores of an Anodized Aluminum Oxide (AAO) template to fabricate the nanowires. The diameter of these nanowires can be altered by changing the anodization parameters of the AAO templates (≈20nm–750nm). The critical diameter for which nanowires show a similar phase transformation behavior to the bulk alloy is experimentally determined to lie between 280nm and 750nm.

Template based chemical vapor deposition (CVD) is a process of effectively fabricating nanostructures such as Carbon nanotube arrays (CNT). During this process, a carbon-carrying precursor gas is used to deposit a layer of solid carbon on the surface of a template within a furnace. Template-based CVD using porous anodized aluminum oxide (AAO) membranes as the template has been applied to efficiently mass-produce CNT arrays which have shown promise for use in gene transfection applications. These AAO membranes are incredibly fragile, making them prone to cracks during handling which can compromise their performance. In order to ease handling of the CNT devices, three-dimensional (3D) printing has been applied to create a support structure for the fragile membranes. The work presented here focuses on the use of 3D printing as a means of integrating CNT arrays into nanofluidic devices, both increasing their useful application and preventing damage to the fragile arrays during handling. 3D printing allows the CNT arrays to be completely encapsulated within the fluidic device by printing a base of material before inserting the arrays. Additionally, 3D printing has been shown to create an adequate seal between the CNT arrays and the printed device without the need for additional adhesives or sealing processes. For this work, a commercially available, fused deposition modeling (FDM) 3D printer was used to print the devices out of polylactic acid (PLA) plastic. This approach has been shown to be effective and repeatable for nanofluidic device construction, while also being cost effective and less time consuming than other methods such as photolithography. Cell culture and has been demonstrated using HEK293 cells on the devices and was found to be comparable to tissue culture polystyrene.