Classical
nanopore sensing relies on the measurement of the ion
current passing through a nanopore. Whenever a molecule electrophoretically
translocates through the narrow constriction, it modulates the ion
current. Although this approach allows one to measure single molecules,
the access resistance limits the spatial resolution. This physical
limitation could potentially be overcome by an alternative sensing
scheme taking advantage of the current across the membrane material
itself. Such an electronic readout would also allow better temporal
resolution than the ionic current. In this work, we present the fabrication
of an electrically contacted molybdenum disulfide (MoS2) nanoribbon integrated with a nanopore. DNA molecules are sensed
by correlated signals from the ionic current through the nanopore
and the transverse current through the nanoribbon. The resulting signal
suggests a field-effect sensing scheme where the charge of the molecule
is directly sensed by the nanoribbon. We discuss different sensing
schemes such as local potential sensing and direct charge sensing.
Furthermore, we show that the fabrication of freestanding MoS2 ribbons with metal contacts is reliable and discuss the challenges
that arise in the fabrication and usage of these devices.
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