New SECM scanning algorithms for improved potentiometric imaging of circularly symmetric targets

To obtain high quality images in scanning probe microscopy (SPM), a certain amount of scanning time is required, depending on the number of sampling points, and the scanning speed. Usually, there is a compromise between scanning speed and image quality. This is most critical in the potentiometric scanning electrochemical microscopy (SECM), which is severely limited by the relatively long response time of the ultramicro-electrode probes. That is, scanning speed can be increased only at the expense of image quality.In a great majority of the SECM studies, the subjects are circularly symmetric systems. In this paper, we present a method to increase SECM imaging speed of such systems, while improving image quality at the same time. It is achieved by using new, polar coordinate-based scanning patterns, exploiting the symmetry of the studied system, and using imaging time more economically. This technique, combined with our previously reported simplex algorithm for automatic target location, significantly improves the imaging of circularly symmetric targets.Numerical simulations and SECM scans using the traditional, and the new scanning algorithms have been performed. The resulting images have been compared with the expected, ideal image.