A long-stroke lifetime piezo inertial actuation and its application in micro-nano observation

Abstract

Instruments used for micro-nano observation, often have optical components with lifespans spanning several decades. While piezo inertial actuators offer the benefit of a compact structure, their limited travel life due to frictional wear poses a challenge for adapting to such applications. Currently, direct-drive piezo and electromagnetic hybrid drives are the preferred commercial solutions; however, hybrid systems tend to increase overall system complexity and size. In this work, we present a compact, wear-adaptive piezo inertial actuator that combines long travel life with cross-scale driving capabilities. Its unique structure ensures stable normal force between friction pairs under surface-to-surface contact conditions, with systematic analysis demonstrating its feasibility for wear adaptation. The XY degrees of freedom (DOFs) exhibited bidirectional motion velocities exceeding 11 mm/s at 2100 Hz and 100 V_p-p. For the Z DOF, at 900 Hz and 100 V_p-p, the forward and reverse velocities were 3.53 mm/s and −4.79 mm/s, respectively. A dual-mode control system integrating fuzzy adaptive PID control and traditional PID control for stepping and scanning modes was developed, effectively addressing the limitations of traditional PID control such as excessive tracking error and slow convergence caused by frequent mode switching. The proposed actuator was applied for various tasks, including graphene surface mechanical characterization, integrated circuit inspection, micro-nano structure detection, and biological cell observation using atomic force and optical microscopes.