The electromechanics of DNA in a synthetic nanopore
We have explored the electromechanical properties of DNA on a nanometer-length scale using an electric field to force single molecules through synthetic nanopores in ultrathin silicon nitride membranes. At low electric fields, E < 200 mV/10 nm, we observed that single-stranded DNA can permeate pores with a diameter >/=1.0 nm, whereas double-stranded DNA only permeates pores with a diameter >/=3 nm. For pores