Smooth trajectories for imaging string-like samples in AFM: A preliminary study

In this paper, we present a high-level feedback control algorithm for rapid imaging in atomic force microscopy (AFM). This algorithm is designed for samples which are string-like, such as DNA and biopolymers. The tip control of the microscope is performed in real-time while probing the unknown sample based on feedback from the tip and a model of the sample. This model is continually updated based on the measurements. To avoid exciting unwanted dynamics in the AFM system, the tip is steered at a constant velocity along a sinusoidal trajectory whose average is the estimate of the sample curve. We discuss the advantages of the algorithm and some of the challenges which must be overcome to make this technique a viable approach to AFM imaging.