Matthew Davenport

Electric-field-induced wetting and dewetting in single hydrophobic nanopores

The behaviour of water in nanopores is very different from that of bulk water. Close to hydrophobic surfaces, the water density has been found to be lower than in the bulk, and if confined in a sufficiently narrow hydrophobic nanopore, water can spontaneously evaporate. Molecular dynamics simulations have suggested that a nanopore can be switched between dry and wet states by applying an electric potential across the nanopore membrane. Nanopores with hydrophobic walls could therefore create a gate system for water, and also for ionic and neutral species. Here, we show that single hydrophobic nanopores can undergo reversible wetting and dewetting due to condensation and evaporation of water inside the pores. The reversible process is observed as fluctuations between conducting and non-conducting ionic states and can be regulated by a transmembrane electric potential.

Nanopores: Graphene opens up to DNA

It might be possible to sequence DNA by passing the molecule through a small hole in a sheet of graphene.

Squeezing ionic liquids through nanopores.

Room temperature ionic liquids (RTILs) are substances composed entirely of ions and are liquids at or below 100 degrees C. Ionic conductivity of RTIL is one of the most important physical properties of these unique substances that determine their potential applications as a new medium for capacitors, fuel and solar cells as well as in separation systems. The quality of performance of these devices relies on the understanding of ionic transport of RTIL on a nanoscale. In this letter, we use ionic current carried by RTILs in single nanopores as a probe for their nanoscale transport properties. We show that the conductivity of RTILs through nanopores is significantly less than corresponding bulk values. Our experiments allowed us to address the nature of the interaction of these confined RTILs with charged surfaces. Electrostatic interactions of RTILs with nanopores are the basis for the formation of ionic diodes rectifying transport of the constituent ions.

Biosensors: Making nanopores from nanotubes

Single-walled carbon nanotubes can be used to detect single DNA molecules as they pass through the nanotubes under the influence of an applied electric field.

Making nanopores from nanotubes.

Single-walled carbon nanotubes can be used to detect single DNA molecules as they pass through the nanotubes under the influence of an applied electric field.

Making nanopores from nanotubes: Biosensors

Single-walled carbon nanotubes can be used to detect single DNA molecules as they pass through the nanotubes under the influence of an applied electric field.