Alternative configuration scheme for signal amplification with scanning ion conductance microscopy

Scanning Ion Conductance Microscopy (SICM) is an emerging nanotechnology tool to investigate the morphology and charge transport properties of nanomaterials, including soft matter. SICM uses an electrolyte filled nanopipette as a scanning probe and detects current changes based on the distance between the nanopipette apex and the target sample in an electrolyte solution. In conventional SICM, the pipette sensor is excited by applying voltage as it raster scans near the surface. There have been attempts to improve upon raster scanning because it can induce collisions between the pipette sidewalls and target sample, especially for soft, dynamic materials (e.g., biological cells). Recently, Novak et al. demonstrated that hopping probe ion conductance microscopy (HPICM) with an adaptive scan method can improve the image quality obtained by SICM for such materials. However, HPICM is inherently slower than conventional raster scanning. In order to optimize both image quality and scanning speed, we report the development of an alternative configuration scheme for SICM signal amplification that is based on applying current to the nanopipette. This scheme overcomes traditional challenges associated with low bandwidth requirements of conventional SICM. Using our alternative scheme, we demonstrate successful imaging of L929 fibroblast cells and discuss the capabilities of this instrument configuration for future applications.