Selective through-holing of anodic porous alumina membranes with large area.

Takashi Yanagishita,Toshiaki Kondo,Yuki Okubo,Hideki Masuda

doi:10.1039/c8ra07646d

Takashi Yanagishita, Toshiaki Kondo + Show 2 more

Open Access

https://doi.org/10.1039/c8ra07646d

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Abstract

Anodic porous alumina membranes with site controlled through-holes were prepared by the formation of a masking layer on the surface of anodic porous alumina and subsequent selective second anodization in concentrated sulfuric acid to form a readily soluble layer. After the anodization, the residual Al substrate was removed, and the highly soluble alumina layer formed in concentrated sulfuric acid was dissolved selectively by wet etching. An advantageous point of this process is the controllability of the pattern of through-holes, and the preparation of large samples with selective through-holes is possible. The pattern of through-holes was controlled by changing the mask pattern formed on the surface of anodic porous alumina. The alumina membranes obtained by this process are expected to be used for various applications that require porous alumina membranes with site controlled through-holes.

Highlights

The preparation of through-hole membranes containing uniform-size holes with submicron to nanometer scales is important because they can be used in various applications, including lters, biosensors, and templates.[1,2,3,4,5,6,7,8,9,10,11,12] Anodic porous alumina, which is formed by the anodization of Al in an acidic solution, is a typical material with an ordered through-hole array
The surface scanning electron microscopy (SEM) image (Fig. 2(b)) shows that single openings were arranged in a square pattern with 5 mm intervals, and the other holes in the anodic porous alumina were covered by the resist mask
To form a highly soluble alumina layer at the bottom of selected holes, a resist mask was formed on the surface of anodic porous alumina, and the sample was anodized in concentrated sulfuric acid

Summary

Introduction

The preparation of through-hole membranes containing uniform-size holes with submicron to nanometer scales is important because they can be used in various applications, including lters, biosensors, and templates.[1,2,3,4,5,6,7,8,9,10,11,12] Anodic porous alumina, which is formed by the anodization of Al in an acidic solution, is a typical material with an ordered through-hole array. This selectively formed a highly soluble alumina layer at the bottoms of the holes in the open sites of the resist mask.

Results

Conclusion