An Integrated Approach to Piezo Actuators Positioning in High-Speed AFM Imaging

In this paper, an integrated approach to achieve atomic force microscope (AFM) imaging of large-size samples at high-speed is proposed, which combines the enhanced inversion-based iterative control (EIIC) technique to drive the piezotube actuator control for lateral x–y axes positioning with the use of a newly-developed dual-stage piezo actuator for vertical z-axis positioning. High-speed, large-size AFM imaging is challenging because large positioning error of the AFM probe relative to the sample can be generated due to the adverse effects—the nonlinear hysteresis and the linear vibration dynamics of the piezotube actuator. In addition, vertical precision positioning of the AFM probe is even more challenging because the desired trajectory is unknown in general, and the probe positioning is also affected by and sensitive to the probe-sample interaction. The main contribution of this article is the development of an integrated approach that combines advanced control algorithm with an advanced hardware platform. The proposed approach is demonstrated in experiments by imaging a large-size (50 μm) calibration sample at high-speed (50 Hz scan rate).