Extended Data Fig. 2: Optical micrographs of Å-channel devices.
From: Beyond steric selectivity of ions using ångström-scale capillaries
(a) Top view of the trilayer assembly (hBN-graphene spacers-hBN) before depositing a gold mask. The graphene spacer is not clearly visible as it is very thin (height, ~0.7 nm). The rectangular microhole in the SiNx membrane is seen in dark blue. Top view of the same device (b) after the gold mask was deposited and (c) after etching away the exposed areas of the 2D crystals.
