Lateral Resolution and Image Formation in Scanning Ion Conductance Microscopy.

Abstract

The scanning ion conductance microscope (SICM) is a powerful tool for imaging the topography of soft samples in an aqueous environment. Despite the rising popularity of the SICM, the image formation process and the fundamental limit of the lateral resolution are still a matter of debate. Using microfabricated samples, we investigated the imaging of small cylindrical particles, elongated objects, and topography steps and present the first direct comparison of numerical and experimental data. For the lateral resolution we considered two alternative definitions: the distance at which two small particles can clearly be resolved from each other in an image, and the apparent full width at half-maximum of small particles. For both definitions, we found a lateral resolution of about 3 times the inner opening radius of the pipet. We further validated this resolution limit in measurements on supported lipid bilayers and a polycarbonate sample using pipets with opening radii down to 8 nm.