Diode-Like Asymmetric Pore
One-sided etching (here from left) results in an asymmetry of ion conduction. Positive ions such as potassium ions (K+) move preferentially from right to left.
The slope of the curve corresponds to the conductance of the asymmetric pore. In the negative voltage regime the conductance is lower in comparison to the positive voltage regime. The phenomenon depends on the acidity of the electrolyte filling the pore and can be used for pH sensors.
This work resulted from a collaboration between GSI Darmstadt and JINR Dubna (Russia), initiated by Christoph Schmelzer and Georgij Nikolaevich Flerov.