Jacob Swett, Pawel Puczkarski, Xinya Bian and Jan Mol, University of Oxford
Towards Recognition Tunnelling Based DNA Sequencing with Graphene Nanogaps
Written by Xun Gong
Nanopore sequencing involves the study of the sequence of polymers via individual interrogation as the polymer traverses an open pore. This type of measurement will allow for long reads of single contiguous molecules, the order of base pairs in the case of DNA. Method of measurement usually electrical, measuring either across the membrane or directly across the pore. Traditionally the field can be divided into biological and solid-state methods, where the former uses biologically available channels as detection components. The advantage of solid state methods revolves around improved tunability and reduced fabrication costs.
This work reports on the fabrication progress and initial data from a solid-state single-molecule graphene nanogap-based biomolecular sensing architecture for DNA sequencing. The device is fabricated on a suspended SiN/Si architecture with metal electrodes fabricated through electron beam lithography and thermal evaporation. Apertures in the SiN, allowing for the translocation of DNA, are fabricated by focused ion beam milling and the graphene nanogaps are formed through a combination of electron beam lithography and feedback-controlled electroburning to create a narrow gap. The graphene is passivated through a dielectric coating with a co-aligned aperture, resulting in a single translocation pathway through the device. The architecture, which requires aligned <10 nm features in multiple layers, is characterized with SEM, AFM, and S/TEM. Due to the narrowness of the channels, this system can potentially achieve single base resolution.