Nanopore-Based DNA Sequencing and DNA Motion Control - Nanopores: Sensing and Fundamental Biological Interactions - page 265

Fig. 11.11 Principle of DNA sequencing via transverse electronic transport. A nanopore is in an
insulating membrane that separates two ionic solution-filled compartments. In response to a voltage
bias (labeled “ ” compartment are

driven, one at a time, into and through the nanopore. The probes across the nanopore serve as
emitter and collector of a tunneling “microscope.” Elevated temperatures and denaturants maintain
the DNA in an unstructured, single-stranded form. (Courtesy of D. Branton, Harvard)

” and “+”) across the membrane, ssDNA molecules in the “

smaller than the diameter of the carbon nanotube. It is also possible for condition (3)
to be satisfied, as shown in the theoretical calculation by Lagerqvist, J. et al .
[ 19 ] in Fig. 11.12 . As pointed out by Zhang X. G. et al . [ 20 ], electron tunneling
depends critically on the distance between the DNA base and the electrodes,
which is a challenge from an experimental point of view. Controlling the motion
of DNA through the nanopore with single base resolution is also a great
challenge, which we will discuss in Section 11.2.

11.1.4.3 Nanopore-Based DNA Sequencing via Semiconductor
Nanopore-Capacitor

A semiconductor nanopore-capacitor device is fabricated from a metal-oxide-
semiconductor (MOS) capacitor, as shown in Fig. 11.13 [ 21 ]. Voltage signals
on the MOS capacitor is induced as the charged DNA molecule is driven
through the nanopore-capacitor by an external voltage bias across the nanopore.
Simultaneous measurements of the current through the pore, the voltages on the
poly and c-Si electrodes, and the voltage on the MOS capacitor are shown
in Fig. 11.14 . The voltage signals on the MOS capacitor are nearly coincident
with an event observed in the ionic current through the pore, which is a proof
that these voltage signals are due to the translocation of a single DNA molecule
through the pore.