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 addition 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 between adjacent wells, the occurrence of SR can be reveled by a peak in that quantity as a function of noise level.