Normal Funnels (NF) were produced by a sequential combination of hard anodization and pore widening steps, and labeled according to the final number of layers. NF2 consist of a 15 µm thick top layer, widened in 5% H3PO4 for 90 min, and a 15 µm thick bottom layer. Similarly, NF3 consist of a 10 µm thick top layer widened for a total of 90 min (2 × 45 min), a middle layer of 10 µm widened for 45 min, and a bottom layer of 10 µm (Figure 1b).