Regensburg 2007 – scientific programme

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BP: Fachverband Biologische Physik

BP 11: Micro- and Nanofluidics

BP 11.4: Talk

Tuesday, March 27, 2007, 16:45–17:00, H43

Ionic currents in nanochannels and carbon nanotubes — •Christine Meyer, Jereon de Grebber, Vishal Merani, Derek Stein, Frank van der Heyden, Marc Zuiddam, Emile van der Drift, and Cees Dekker — Kavli Institute of Nanoscience, TU Delft, The Netherlands

The behaviour of electrolyte solutions in small confinements can differ a lot from bulk behaviour. This makes salt solutions in artificial nanofluidic channels an interesting subject for investigation.

Nanofluidic channels were fabricated using a sacrificial etch process. A sacrificial silicon layer that mimics the channel is covered with silicon oxide. Once the sacrificial layer is etched away selectively, a channel is created that we fill with an electrolyte solution. Using the same fabrication scheme, we plan to integrate a single-wall carbon nanotube as an ultimately small fluidic channel.

We investigated the ionic conductance of nanochannels as a function of salt concentration and found a saturation in the low-salt regime. With respect to the expected bulk conductance, the current in the saturation regime is enhanced. We can explain this by assuming that ions in the Debye layer, i.e. ions that screen surface charges, become the dominant charge carriers in this regime. If we can change the surface charge e.g. electrically, the conductance of the channel should change accordingly, which would lead to an ”ionic transistor”.