An algorithm for boundary tracking in AFM

The standard approach to investigating dynamic phenomena in atomic force microscopy (AFM) is through the use of time-lapse imaging techniques. Because the time to acquire each image is often on the order of minutes, the temporal resolution of this approach is severely limited. There are a variety of examples where the interesting dynamics occur on the boundary of a contiguous structure, such as the growth of lamellar protrusions for cell motility, the growth of crystal structures, or the process of endocytosis by cells. Motivated by this, we present here a high-level feedback control law for boundary tracking in AFM. By steering the tip of the atomic force microscope along the boundary, the acquired image is restricted only to the area of interest. With this approach the total area which needs to be imaged is drastically reduced, leading to a great reduction in the time to acquire each image