Table 2.

Summary of the most representative pore geometries in NAA produced by different electrochemical approaches.

Type of NAA	Electrochemical approach	References
Modulated	modulated anodisation profile	[18,21,22]
Hierarchical	asymmetric two-step anodisation	[23,24]
Serrated	anodisation at low voltage and high temperature	[25,26]
Three-dimensional	modulated anodisation profile and final wet chemical etching	[27,28]
Multilayered	stepwise or pulse anodisation	[29,30,31,32,33]
Funnel-like	combination of multiple anodisation and pore widening steps	[34,35,36,37,38,39]