title: Fast and low-noise tunnelling current measurements for single-molecule detection in an electrolyte solution using insulator-protected nanoelectrodes.
abstract: Reliable ways of DNA sequencing by tunnelling current require low-noise and high-speed measurements of tunnelling current in aqueous environments. Here we report a use of insulator-protected nanoprobes for achieving 7.6 pA rms noise at 50 kHz sampling rates in an electrolyte solution. We utilized dielectric-covered mechanically-controllable break junctions to create a pair of nano-exposed insulator/Au coaxial electrodes closely separated by 1 nm. We observed insulator layer thickness dependent noise levels, which was attributed to decreased capacitance through replacing capacitive electric double layers by the low-k dielectrics. We also demonstrated the detection of sharpened features in tunnelling current signatures that reflect dynamic motions of single-nucleotides in the electrode gaps by virtue of suppressed smearing effects in the low-capacitance nanoelectrode system.
authors.affiliation: The Institute of Scientific and Industrial Research, Osaka University, Japan. tsutsui@sanken.osaka-u.ac.jp taniguti@sanken.osaka-u.ac.jp.
authors.forename: Takanori
authors.initials: T
authors.lastname: Morikawa
authors.affiliation: The Institute of Scientific and Industrial Research, Osaka University, Japan. tsutsui@sanken.osaka-u.ac.jp taniguti@sanken.osaka-u.ac.jp.
authors.forename: Kazumichi
authors.initials: K
authors.lastname: Yokota
authors.affiliation: The Institute of Scientific and Industrial Research, Osaka University, Japan. tsutsui@sanken.osaka-u.ac.jp taniguti@sanken.osaka-u.ac.jp.
authors.forename: Makusu
authors.identifier: http://orcid.org/0000-0002-4552-1163
authors.initials: M
authors.lastname: Tsutsui
authors.affiliation: The Institute of Scientific and Industrial Research, Osaka University, Japan. tsutsui@sanken.osaka-u.ac.jp taniguti@sanken.osaka-u.ac.jp.
authors.forename: Masateru
authors.initials: M
authors.lastname: Taniguchi