This fact is in contrast to a previous observation that the termination of nanopores affects the signals significantly when reading DNA by measuring transverse electric current for each nucleobase. The nanopores might be drilled by the focused electron beam of a transmission electron microscope. An alternative approach to this end is to assemble the porous graphene sheet from building blocks, which has been used to construct a two dimensional framework with sub-2-nm channels by the dynamic trimerization of terephthalonitrile.