Size-Tunable Porous Anodic Alumina Nano-Structure for Biosensing

A porous anodic alumina (PAA) film has been investigated to realise highly-ordered nano-porous structures. A two-step anodization process is used to anodize aluminium into size-controllable aluminium oxide. In this paper, we investigate how anodization parameters affect nano-porous structures, such as voltage and time of pretreatment, anodization voltage and time, pore widening time. The results showed pretreatment is important to obtain a smooth surface for anodizing. The pore size is controllable between 30 and 80 nm, with a linear fit curve. The interpore size is constant at around 95 nm, and the pore densities are between 1010 and 1011 cm–2. The formation of straight vertical walls is crucial if the PAA film is to be subsequently used as the template for the growth of metal nanowire arrays.