Single nucleotide discrimination with sub-two nanometer monolayer graphene pore

The effective sensing area is the key point of solid-state nanopore single-molecule detection, which is determined by the diameter of the hole and the thickness of the membrane. High spatial resolution can be achieved by using single-atom thickness two-dimensional materials, such as single-layer graphene and molybdenum disulfide. Helium ion beam microscopy provides an effective technique for manufacturing small-sized nanopores. Here, we show that the precise fabrication of sub-2 nanometer nanopores has been successfully achieved on a single-layer graphene film, which provides the best spatial resolution in room-temperature ionic liquid-assisted singlemolecule detection. Many graphene nanopores of different sizes have been fabricated, with a minimum pore diameter of 1.4 nm. The application of these graphene nanopores manufactured by HIM shows that single-layer graphene nanopores can distinguish different homopolymer single-stranded DNA lengths and types, and can even identify four single nucleotides.