On-chip microvalves regulate electrical and fluidic access to an array of nanopores integrated within microfluidic networks. This configuration allows for on-chip sequestration of biomolecular samples in various flow channels and analysis by independent nanopores.
Integrating
nanopore sensors within microfluidic architectures
is key to providing advanced sample processing capabilities upstream
of the biosensor. When confined in a microchannel, the nanopore capture
and translocation characteristics are altered when subjected to cross-flow,
affecting sensor performance. Here, we study the capture rate and
translocation of 1–5 kbp double-stranded DNA molecules through
solid-state nanopores in the presence of tangential fluid flow over
the nanopore aperture. Experiments reveal a trend of increased capture
rate with cross-flow, reaching a 5-fold enhancement (dependent on
DNA length) at moderate flow rates, before decreasing at higher flow
rates. By modeling DNA dynamics in microchannels under the combined
effect of laminar flow, Brownian motion and electrophoretic drift,
it is shown that the observed trend is the result of two competing
mechanisms: enhanced DNA transport by convection and reduction in
the nanopore’s capture volume with increased flow velocity.
Moreover, it is shown that the viscous drag force exerted by flow
on a translocating DNA can be exploited to tune the kinetics of DNA
translocation.
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