  Sequencing by tunneling is a next-generation approach to read single-base
information using electronic tunneling transverse to the single-stranded DNA
(ssDNA) backbone while the latter is translocated through a narrow channel. The
original idea considered a single pair of electrodes to read out the current
and distinguish the bases [1, 2]. Here, we propose an improvement to the
original sequencing by tunneling method, in which $N$ pairs of electrodes are
built in series along a synthetic nanochannel. While the ssDNA is forced
through the channel using a longitudinal field it passes by each pair of
electrodes for long enough time to gather a minimum of $m$ tunneling current
measurements, where $m$ is determined by the level of sequencing error desired.
Each current time series for each nucleobase is then cross-correlated together,
from which the DNA bases can be distinguished. We show using random sampling of
data from classical molecular dynamics, that indeed the sequencing error is
significantly reduced as the number of pairs of electrodes, $N$, increases.
Compared to the sequencing ability of a single pair of electrodes,
cross-correlating $N$ pairs of electrodes is exponentially better due to the
approximate log-normal nature of the tunneling current probability
distributions. We have also used the Fenton-Wilkinson approximation to
analytically describe the mean and variance of the cross-correlations that are
used to distinguish the DNA bases. The method we suggest is particularly useful
when the measurement bandwidth is limited, allowing a smaller electrode gap
residence time while still promising to consistently identify the DNA bases
correctly.
