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Bilayer Graphene Lateral Contacts for DNA Sequencing

Translocation of DNA through a nanopore with embedded electrodes is at the centre of new rapid inexpensive sequencing methods which allow distinguishing the four nucleobases by their different electronic structure. However, the subnanometer separation between nucleotides in DNA requires ultra-sharp probes. Here, we propose a device architecture consisting of a nanopore formed in bilayer graphene, with the two layers acting as separate electrical contacts. The 0.34 nm interlayer distance of graphene is ideally suited for electrical coupling to a single nucleobase, avoiding the difficulty of fabricating probes with subnanometer precision. The top and bottom graphene electrodes contact the target molecule from the same lateral side, removing the orders-of-magnitude tunneling current variations between smaller pyrimidine bases and larger purine bases. We demonstrate that incorporating techniques for molecular manipulation enables the proposed device to sequence single-stranded DNA and that it offers even the prospect of sequencing double-stranded DNA.