Person:

Lu, Bo

Voltage-biased solid-state nanopores are well established in their ability to detect and characterize single polymers, such as DNA, in electrolytes. The addition of a pressure gradient across the nanopore yields a second molecular driving force that provides new freedom for studying molecules in nanopores. In this work, we show that opposing pressure and voltage bias enables nanopores to detect and resolve very short DNA molecules, as well as to detect near-neutral polymers.

Nanopores in graphenemembranes can potentially offer unprecedented spatial resolution for single molecule sensing, but their fabrication has thus far been difficult, poorly scalable, and prone to contamination. We demonstrate an in-situfabrication method that nucleates and controllably enlarges nanopores in electrolyte solution by applying ultra-short, high-voltage pulses across the graphenemembrane. This method can be used to rapidly produce graphenenanopores with subnanometer size accuracy in an apparatus free of nanoscale beams or tips.

We report the formation of a tunable single DNA molecule trap near a solid-state nanopore in an electrolyte solution under conditions where an electric force and a pressure induced viscous flow force on the molecule are nearly balanced. Trapped molecules can enter the pore multiple times before escaping the trap by passing through the pore or by diffusing away. Statistical analysis of many individually trapped molecules yields a detailed picture of the fluctuation phenomena involved, which are successfully modeled by a one-dimensional first passage approach.