| Two kinds of heterogeneous materials, block copolymer films and Nafion membranes, were studied by using current sensing atomic force microscopy (CSAFM). In calculated results, correlation between surface morphology and surface conductance images obtained using CSAFM, and the implication of surface conductance and its variations are analyzed. We found that if the diameter of a CSAFM probe tip is much smaller than the correlation length of the surface morphological features, the current sensing image obtained using the probe has little correlation with the surface morphology, and the current sensed by a CSAFM indeed reflects the variation of local resistivity on the sample surface. In experimental results, the microphase separation of block copolymer and the current passing through the ion channel in Nafion membranes were observed by CSAFM. This demonstrated that the CSAFM is a powerful and important tool for studying heterogeneous materials. |
