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 \mathrm {\mu }\text{m} ( {x} -axis), 102.8 \mathrm {\mu }\text{m} ( {y} -axis), and 5.22 \mathrm {\mu }\text{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.