An Electromagnetic-Piezoelectric Hybrid Actuated Nanopositioner for Atomic Force Microscopy

An electromagnetic-piezoelectric hybrid actuated nanopositioner for atomic force microscopy (AFM) is proposed. Applying the hybrid serial-parallel-kinetic design, the parallel xy-stage is actuated by the normal-stressed electromagnetic actuators (NSEAs) to conduct planar scanning in a large scope. The z-axis is serially carried by the xy-stage and is actuated by a piezoelectric actuator (PEA) to track the sample's topography with high speed. Moreover, a novel flexure mechanism is proposed for motion guidance and decoupling of the xy-stage, featuring the higher resonant frequency along the x-axis to satisfy the requirement of a faster planar axis in AFM imaging. The analytical model of the nanopositioner is established to optimally determine the parameters, and the results are verified by finite-element analysis. A prototype is fabricated and tested. Experimental results demonstrate that the triaxial strokes of 94.4 mu m (x-axis), 102.8 mu m (y-axis), and 5.22 mu m (z-axis) are achieved, and the resonant frequencies are identified as 735 Hz (x-axis), 650 Hz (y-axis), and 6340 Hz (z-axis), respectively. The implemented feedback controllers ensure the accuracy of high-speed trajectory tracking. Finally, the AFM imaging based on the proposed nanopositioner is conducted, confirming its effectiveness for large-scope and high-rate AFM imaging.