Increasing the speed of solid-state nanopores

Abstract

In this work, the authors studied the time response of solid-state nanopores to the applied potentials and the corresponding capacitances. They primarily examined the effect of the doping of the silicon substrates as well as the addition of dielectrics above and below the device membrane. For simple silicon nitride membranes on a moderately doped Si, the measured RC time constants in 1M KCl are on the order of hundreds of microseconds or larger. The authors found that the silicon substrate's doping level has a significant effect on the equivalent circuit of the device and the use of a more lightly doped Si significantly speeds up the device response. They attributed this effect to the reduction of depletion layer capacitance at the Si-electrolyte interfaces. In the best device structure tested, time constants of ∼425 ns were observed in 1M KCl, which is much faster than most DNA translocation times and on the same order of magnitude as the transit time of each base through typical nanopores. © 2011 American Vacuum Society.