An Electromagnetic-Piezoelectric Hybrid Actuated Nanopositioner for Atomic Force Microscopy
Lingwen Tan, Xiangyuan Wang, Qi Yu, Bocheng Yu, Yixuan Meng, Linlin Li, Xinquan Zhang, Limin Zhu
Abstract
An electromagnetic-piezoelectric hybrid actuated nanopositioner for atomic force microscopy (AFM) is proposed. Applying the hybrid serial-parallel-kinetic design, the parallel <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xy</i> -stage is actuated by the normal-stressed electromagnetic actuators to conduct planar scanning in a large scope. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> -axis is serially carried by the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xy</i> -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 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xy</i> -stage, featuring the higher resonant frequency along the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> -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 μm (x-axis), 102.8 μm ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i> -axis), and 5.22 μm ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> -axis) are achieved, and the resonant frequencies are identified as 735 Hz ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> -axis), 650 Hz ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i> -axis), and 6340 Hz ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> -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.