Feed-Forward Compensation for High-Speed Atomic Force Microscopy Imaging of Biomolecules

High-speed imaging by atomic force microscopy (AFM) requires the implementation of a fast control of tip–surface distance to maintain a constant interaction force. In particular, a well-controlled low load force is essential for observing soft biological molecules without causing damage to the sample. The accurate control of tip–surface distance where only feedback control is used is intrinsically difficult particularly for fast scanning. Here, we demonstrate that the combination of feedback and feed-forward control is useful for a more accurate distance control. We evaluate the bandwidth performance of the closed loop with and without feed-forward compensation using a model AFM system.We show that the combination of feedback and feed-forward control yields a greater than two fold improvement in bandwidth. We have applied this technique to the observation of myosin V and actin filaments at a high scanning rate.