Dresden 2017 – wissenschaftliches Programm

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MI: Fachverband Mikrosonden

MI 8: Scanning Probe Microscopy (SPM)

MI 8.4: Vortrag

Donnerstag, 23. März 2017, 10:45–11:00, MER 02

A Quantitative Model for the Ion Current vs. Distance Behavior in Scanning Ion Conductance Microscopy — •Johannes Rheinlaender and Tilman E. Schäffer — Institute of Applied Physics, Eberhard Karls University Tübingen, Germany

Scanning ion conductance microscopy (SICM) is an emerging scanning probe microscopy technique in biophysical and electrochemical research. It is based on raster-scanning an electrolyte-filled nanopipette across the sample, while the ion current through the nanopipette serves as a measure for the tip-sample distance. However, so far there is no quantitatively validated model for the ion current vs. distance behavior in SICM, although it is the central functional principle of the technique. To quantitatively predict the ion current vs. distance behavior, we here provide two theoretical models: (1) an analytical model to investigate the dimensional dependencies and (2) a numerical model for even higher accuracy based on finite element modeling (FEM). We verified the models using experimental data recorded with nanopipettes of known geometry and opening radii between 30 and 300 nm. The new models therefore allow, for the first time, to quantify the tip-sample distance in SICM. Furthermore, as the ion current vs. distance behavior directly depends on the tip geometry of the nanopipette, the models can also vice versa be used to quantify the tip geometry from experimental ion current data. This provides a unique, non-destructive way of calibrating the nanopipettes tip geometry within the running SICM experiment.