Observation of Stochastic Resonance in Transport of the DNA between Entropic Traps*

We describe a nanofluidic system in which stochastic resonance (SR) could
be observed in the motion of single DNA molecules. SR is a nonlinear dynamical
phenomenon occurring in bistable systems where a weak signal that is below a
sensor’s threshold for detection can be boosted and made detectable with ad-
dition of white noise. We fabricated nanofluidic devices with embedded pits
that give rise to a bistable landscape for confined DNA molecules. An applied
periodic pressure generates a weak periodic force on the DNA that represents a
sub-threshold signal. We also developed a technique to control the noise inside
a nano-fluidic device using electrokinetic forces. By computing the correlation
between the periodic driving signal and the measured hoping of molecules be-
tween adjacent wells, the occurrence of SR can be reveled by a peak in that
quantity as a function of noise level.