Ordered Anodic Porous Alumina Research Articles

Fabrication of Ideally Ordered Anodic Porous Alumina on Glass Substrates by Stamping Process Using Flexible Stamps

Establishing a process to fabricate anodic porous alumina with an ordered array of uniform-sized pores on a substrate is an important challenge of fabricating various functional devices. In this study, ordered anodic porous alumina was fabricated on glass substrates by a stamping process using a flexible stamp. This process enables the formation of a resist mask at a low pressure on the sample surface to pattern the starting point for pore generation during anodization. Therefore, it is possible to pattern samples without breaking the glass substrate, and subsequent anodization can generate ordered anodic porous alumina on the substrate. The stamping process using flexible stamps can be applied regardless of the roughness of the Al film on a substrate because the stamp deforms according to the Al surface shape, even when there is a protruding structure on the Al surface. In addition, it was shown that this process could be used to form ordered anodic porous alumina even on Al surfaces with three-dimensional curvatures, such as convex lenses.

Highly Ordered Anodic Porous Alumina Prepared by Anodization of Al in Extremely Dilute H2SO4

Highly ordered anodic porous alumina with a period of ca. 90–160 nm was prepared by anodization using extremely dilute sulfuric acid. The hole period of anodic porous alumina was controllable in the range of 90–160 nm by changing the anodization voltage. The thickness of the oxide film obtained by the anodization of Al in extremely dilute sulfuric acid was nonuniform. However, we found that the addition of a small amount of phosphoric acid to the electrolyte improved the uniformity of the thickness of the oxide film obtained. The ordered anodic porous alumina obtained in this study is expected to be a starting material for fabricating various functional devices.

Preparation of Ideally Ordered Anodic Porous Alumina by Prepatterning Process Using a Flexible Mold

Ideally ordered anodic porous alumina with controlled interpore distances was formed by fabricating a resist mask using a flexible mold and subsequent anodization. Prior to forming the resist pattern on the surface of an Al substrate, Al was pre-anodized at 10 V to prepare the fine porous structure, which acts as a resist adhesive layer. After the formation of the resist mask using a flexible mold, an arranged array of cavities with Al exposed at the bottom was formed by the selective dissolution of the oxide layer at resist openings. The subsequent anodization of the sample with the cavity array generated ideally ordered anodic porous alumina because alumina holes were formed at the bottom of cavities during anodization. This process allows the preparation of ideally ordered anodic porous alumina even on a curved Al surface owing to the flexibility of the mold. In addition, this process can also be applied to the preparation of an ideally ordered anodic porous alumina with a large sample area because the Al substrate can be patterned without high pressure. The obtained sample can be used for various applications requiring an ideally ordered hole array structure.

Ideally Ordered Anodic Porous Alumina on Si Substrate Prepared by Anodization of Sputtered Al–Mg Thin Film

Anodic porous alumina with an ideally ordered hole arrangement was formed on a Si substrate by nanoimprinting and subsequent anodization. In this process, the arrayed shallow dimples formed by nanoimprinting using a mold act as initiation sites of hole development during the anodization. To realize the precise transfer of the mold patterns to the Al surface during nanoimprinting, we used sputtered Al alloy film as a starting material. This is because the Al alloy with appropriate impurities as a sputtering target can suppress the crystal grain growth during sputtering and allow the formation of Al alloy films with smooth surfaces on the substrate. Dimple arrays with 100 nm intervals could be formed on the flat surface of the Al–Mg film on the Si substrate. Ideally ordered anodic porous alumina with an interpore distance of 100 nm was successfully obtained by subsequent anodization. A Co/alumina composite was also obtained by the electrodeposition of Co into the alumina holes. The obtained samples are expected to be applied to various functional devices requiring an ideally ordered structure on a substrate.

Preparation of Ordered Anodic Porous Alumina with Single-Nanometer-Order-Size Holes by Atomic Layer Deposition.

Ordered anodic porous alumina with controlled-size holes on the order of a single-nanometer scale was obtained by the atomic layer deposition (ALD) of Al2O3 or TiO2. The thin metal oxide layers of uniform thickness were formed successfully on the inner wall of the hole of the ordered anodic porous alumina with high aspect ratios by ALD. The hole diameter of the ordered anodic porous alumina could be controlled precisely by adjusting the number of cycles of ALD. The obtained anodic porous alumina with an ordered hole arrangement of reduced holes will be applied to various application fields requiring uniform-sized holes on the order of a single-nanometer scale, such as the starting material for preparing various types of quantum effect devices.

Preparation of Monodisperse Nanoparticles by Membrane Emulsification Using Ordered Anodic Porous Alumina and Its Application to Batteries

Preparation of Monodisperse Nanoparticles by Membrane Emulsification Using Ordered Anodic Porous Alumina and Its Application to Batteries

Preparation of Polymer Nanofibers with Controlled Diameters by Continuous Spinning Using Ordered Anodic Porous Alumina as Spinneret

Polymer nanofibers with controlled diameters were formed by continuous spinning using ordered anodic porous alumina as a spinneret. The diameter of the polymer nanofibers could be controlled by cha...

Preparation of Ordered Anodic Porous Alumina and Its Functional Applications

Preparation of Ordered Anodic Porous Alumina and Its Functional Applications

(Invited) Preparation of Ordered Anodic Porous Alumina Through-Hole Membrane and Its Applications

Anodic porous alumina, which is a typical self-ordered nanohole array material formed by anodization of Al in an appropriate acid solution, has recently attracted increasing interest as a key material for the fabrication of functional devices1,2). For the various applications of ordered anodic porous alumina, the preparation of through-hole membranes is important. The fabrication process for porous alumina through-hole membranes has been investigated for a long time3). However, a facile and reliable process that does not require special techniques has not yet been established. To overcome this problem, we have been developing a new high-throughput process for fabricating through-hole alumina membranes4). This process is based on the new finding that through-hole membranes can be easily obtained by dissolving a two-layered sample in an appropriate etchant, which was formed by a first anodization under standard anodizing conditions and a subsequent anodization in concentrated H2SO4. This is because the oxide layer formed in the concentrated H2SO4 can be easily dissolved in an appropriate etchant. After the detachment of the membrane, the residual Al substrate could be repeatedly used for the preparation of ordered through-hole membranes. In this report, recent results of the preparation of ordered anodic porous alumina through-hole membranes and its applications will be presented. References 1) T. Yanagishita and T. Hidaka, M. Suzuki, and H. Masuda, J. Vac. Sci. Technol. B, 34, 021804 (2016). 2) H. Masuda and K. Fukuda, Science, 268, 1466 (1995). 3) H. Masuda and M. Satoh, Hpn. J. Appl/ Phys., 35, L126 (1996). 4) T. Yanagishita and H. Masuda, Electrochim. Acta, 184, 80 (2015).

(Invited) Fabrication of Highly Ordered Anodic Porous Alumina and Its Applications to Functional Nanodevices

The anodic porous alumina, which is formed by anodization of Al in an acidic electrolyte, has attracted much interest as the starting materials for various types of functional nanodevices due to its unique geometrical structures.1) It has been reported that long-range-ordered anodic porous alumina with an ideally ordered hole arrangement can be obtained under appropriate anodization conditions.2-4) Such ordered structures are useful for the preparation of the functional nanodevices, which require the ordered nano- structures. The control of hole intervals and hole sizes of anodic porous alumina while retaining the long-range ordered hole arrangement is very important for expanding the application fields of the anodic porous alumina. As an example of the expansion of the range of the hole intervals and hole sizes with long-range ordered hole arrangement, we have shown the formation of long-range-ordered anodic porous alumina with reduced hole intervals and hole sizes. In this process, highly ordered anodic porous alumina with reduced hole interval of ~25 nm can be obtained by the appropriate anodizing condition5,6). In the present report, the formation of the highly ordered anodic porous alumina with various hole intervals and hole sizes will be presented. In addition, the template synthesis of the ordered nanostructures with reduced dimensions will be also reported. 1. T. Yanagishita, T. Hidaka, M. Suzuki, and H. Masuda, J. Vac. Sci. Technol. B, 34, 021804 (2016). 2. H. Masuda and K. Fukuda, Science, 268, 1466 (1995). 3. H. Masuda, F. Hasegawa, and S. Ono, J. Electrochem. Soc., 144,L127 (1997). 4. H. Masuda, K. Yada, and A. Osaka, Jpn. J. Appl. Phys., 37, L1340 (1998). 5. H. Masuda, M. Nagae, T. Morikawa, and K. Nishio, Jpn. J. Appl. Phys., 45, L406 (2006). 6. H. Masuda, K. Takenaka, T. Ishi, and K. Nishio, Jpn. J. Appl. Phys., 43, L1165 (2006).

(Invited) Preparation of Ordered Anodic Porous Alumina Through-Hole Membrane and Its Applications

The preparation of highly ordered anodic porous alumina through-hole membranes by two-layer anodization using concentrated sulfuric acid solution is described in detail. After the formation of a porous alumina layer in an oxalic acid solution, a highly soluble alumina layer was formed at the lower part of the first alumina layer by second anodization in a concentrated sulfuric acid solution. A porous alumina through-hole membrane was then obtained by selective dissolution of the second alumina layer in an appropriate etchant. The residual Al could be reused for the preparation of the ordered anodic porous alumina because an ordered concave array corresponding to the hole arrangement of the detached porous alumina membrane was maintained at the surface of the residual Al even after the etching treatment. The present process allows the high-throughput preparation of ordered anodic porous alumina through-hole membranes.

高規則性アノード酸化ポーラスアルミナにおける最近の機能化研究

高規則性アノード酸化ポーラスアルミナにおける最近の機能化研究

Preparation of Monodisperse Hydrogel Particles by Membrane Emulsification Using Highly Ordered Anodic Porous Alumina

Abstract Monodisperse hydrogel particles were prepared by membrane emulsification using ordered anodic porous alumina. The size of the obtained hydrogel particles could be controlled by changing the pore size in the anodic porous alumina. The average diameter of the obtained hydrogel particles showed a good linear relationship with the pore size of anodic porous alumina used for membrane emulsification. The process is simple and allows for the high-throughput preparation of monodisperse hydrogel particles with controlled sizes.

Nanoimprinting Process Using Highly Ordered Anodic Porous Alumina

An anodic porous alumina with precisely controlled size and depth of holes was prepared and used for nanoimprinting of a polymer. As a typical application of nanoimprinting, antireflection (AR) structures of polymer were prepared. The obtained AR structure with optimized geometrical structures exhibited a low reflectance of less than 0.2 %. The present process allows the high throughput production of polymer AR structures with large sizes.

Nanoimprinting Process Using Highly Ordered Anodic Porous Alumina

not Available.

Fabrication of Metal–Polymer Nanocomposite with Beaded Structures Using Ordered Anodic Porous Alumina Template

Abstract The fabrication of nanocomposites consisting of uniform-sized metal nanoparticles arranged at uniform intervals in a fibrous polymer matrix is described. The combined process of metal deposition into periodic holes in anodic porous alumina and polymer injection into the holes yielded metal (Au, Ag)–polymer composite structures. In the obtained composition, metal nanoparticles are arranged at equal spaces in a fibrous polymer matrix.

Preparation of Uniform-sized Polymer Nanofibers by Extrusive Spinning Using Ordered Anodic Porous Alumina

Abstract Uniform-sized polymer nanofibers were fabricated by the extrusive spinning of a photocurable monomer under UV irradiation using ordered anodic porous alumina as a nozzle for the spinning. The size of the resulting polymer nanofibers could be controlled by adjusting the pore size of the anodic porous alumina membrane.

Fabrication of Monodisperse Polymer Nanoparticles by Membrane Emulsification Using Ordered Anodic Porous Alumina

Uniformly sized droplets of photocurable monomer were obtained through membrane emulsification using highly ordered anodic porous alumina as a membrane. Subsequent polymerization of the monomer generated polymer particles, whose sizes could be controlled by changing the size of the pores in anodic porous alumina. The size distribution was very narrow owing to the uniformity of pore size in the anodic porous alumina used for the emulsification.

Nanoimprinting Using Highly Ordered Anodic Porous Alumina with Reduced Hole Periods

Nanoimprinting Using Highly Ordered Anodic Porous Alumina with Reduced Hole Periods

Functional Biosensor Using Nanodisk Electrode Array Prepared by Ideally Ordered Anodic Porous Alumina

not Available.