Preparation of Ni micropillar arrays with high aspect ratios using anodic porous alumina template and their application to molds for imprinting

Yanagishita, Takashi; Hayakawa, Tomohiro; Kondo, Toshiaki; Masuda, Hideki

doi:10.1039/d0ra09729b

Cited by 4 publications

(4 citation statements)

References 19 publications

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“…The alumina layer at the resist openings was completely dissolved, not only on the surface but also in the depth direction, exposing the Al substrate at the bottom of the micrometer-sized pores. This is because the etchant penetrated the bottom of the pore of anodic porous alumina during etching, resulting in uniform dissolution from the top to the bottom of the pore …”

Section: Resultsmentioning

confidence: 99%

“…As the thickness of the resulting anodic porous alumina corresponds to that of the framework layer, the thickness of the framework was controlled in the range of 30–100 μm by varying the anodization time. A resist mask was formed on the ordered anodic porous alumina using a poly(dimethylsiloxane) (PDMS) stamp with a square array of micrometer-sized convex patterns (Figure (b)). , The PDMS stamp was prepared by molding an original pattern fabricated by electron beam lithography as a template. To form the resist film on the surface of the PDMS stamp, the stamp was immersed in a toluene solution containing 0.5 wt % polychloroprene at 30 °C, held for 10 s, and then pulled up at a constant speed of 0.5 mm s –1 using a desktop dip coater (DC4200, Aiden, Japan).…”

Section: Experimental Sectionmentioning

confidence: 99%

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Preparation of Alumina Membrane Filters with Framework Structures by Al Anodization

Boushi,

Yanagishita

2024

Langmuir

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Alumina membrane filters consisting of a thin filter layer (200−700 nm in thickness) supported by a framework (30−100 μm in thickness) were fabricated on the basis of the anodization of an Al substrate. The solution permeability of alumina membrane filters with tubular pores of uniform size and shape varies with membrane thickness; therefore, membrane filters with a filter layer thickness of less than 1 μm showed high solution permeability. Although the filter layer is thin, it is reinforced by a thick framework, enabling the fabrication of large freestanding membrane filters (2.5 × 2 cm 2 in size). The pore size of the anodic porous alumina formed by the anodization of Al can be controlled in the range from 10 nm to ca. 2 μm by varying the preparation conditions. The alumina membrane obtained by this method is therefore useful as a membrane filter that can efficiently separate particles of various sizes, including microplastics, viruses, and bacteria. This method enables the fabrication of membrane filters with uniform pore size, high solution permeability, and sufficient mechanical strength for handling as freestanding membranes, which have been difficult to achieve with the reported preparation processes for membrane filters. The obtained membrane filters with frameworks can be applied to efficient microfiltration.

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Section: Resultsmentioning

confidence: 99%

Section: Experimental Sectionmentioning

confidence: 99%

Preparation of Alumina Membrane Filters with Framework Structures by Al Anodization

Boushi,

Yanagishita

2024

Langmuir

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“…First, anodic porous alumina with hierarchical structures was prepared by an integrated process composed of anodization and selective patterning. 27,28 Next, polymer negatives of anodic porous alumina with the hierarchical structures were formed, and nally, the exible mold was obtained by molding using the polymer negative as a mold. This process can effectively form high-aspect-ratio micropillars with nanopillar arrays at their tips on curved surfaces.…”

Section: Introductionmentioning

confidence: 99%

Micro-nano hierarchical pillar array structures prepared on curved surfaces by nanoimprinting using flexible molds from anodic porous alumina and their application to superhydrophobic surfaces

2022

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“…This process is based on the previously reported technique using a resist mask for selective etching with a flexible mold of poly (dimethylsiloxane) (PDMS). [16][17][18] If the resist mask formed on the surface of the Al substrate can control the starting point of hole development during anodization, ideally ordered anodic porous alumina can be obtained without the need to press a hard mold under high pressure. This also means that an ideally ordered nanohole array with a large area can be obtained without the deterioration of the molds.…”

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confidence: 99%

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

Yanagishita

Kato

Shirano

et al. 2022

ECS J. Solid State Sci. Technol.

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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.

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Preparation of Ni micropillar arrays with high aspect ratios using anodic porous alumina template and their application to molds for imprinting

Abstract: Ni micropillar array with high aspect ratio prepared using anodic porous alumina.

Cited by 4 publications

References 19 publications

Preparation of Alumina Membrane Filters with Framework Structures by Al Anodization

Preparation of Alumina Membrane Filters with Framework Structures by Al Anodization

Micro-nano hierarchical pillar array structures prepared on curved surfaces by nanoimprinting using flexible molds from anodic porous alumina and their application to superhydrophobic surfaces

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

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