A laminated hybrid structure of bulk PZT and electrohydrodynamically printed thick films for miniature modal composite piezoelectric motors

Abstract

This study proposes a laminated hybrid excitation structure composed of bulk PZT piezoelectric ceramics and electrohydrodynamically printed PZT thick films for driving a miniature modal composite piezoelectric motor. By employing electrohydrodynamic printing to achieve continuous and precise micrometre-scale thickness compensation in high-strain regions, precise consistency regulation of the target resonant frequencies is realised while maintaining a high driving capability of the bulk PZT piezoelectric ceramics. With a total mass of only 0.13 g, the tiny motor exhibits a driving speed per unit mass and voltage that is ten times higher than that of piezoelectric motors of the same type. Scanning electron microscopy images of the surface and cross-section of the printed piezoelectric ceramic show that the PZT particles are uniformly distributed and the film surface is smooth, with good thickness uniformity and a printed thickness of 38 μm. X-ray diffraction patterns exhibit the characteristic diffraction peaks of a perovskite structure, indicating a favourable functional phase composition. The thick film exhibits a remanent polarization intensity (Pr) of 15.5 μC/cm², which is twice that of the PZT film fabricated by the spin-coating method. The motor prototype achieves a linear velocity of 12.13 mm/s, with a velocity per unit mass voltage of 2.67 mm/(V·g), an order of magnitude greater than comparable micro-motors. Finally, the miniature motor has been successfully applied to precision stepping drive of microlenses, enabling laser beam focusing adjustments from 3270 to 23,900 lx, validating that this hybrid laminated structure provides a new strategy for the miniaturisation of piezoelectric devices.