A Nanoscale-Resolution and Low-Coupling Two-DOF Piezoelectric Microgripper for Micromanipulation

Micromanipulation technology has played a pivotal role in advancing fields such as biomedicine, micro/nano manufacturing, and materials science, while the continuous progress in these domains imposes increasingly stringent requirements on the precision and multifunctionality of micromanipulation systems. Most existing microgrippers are limited to single degree-of-freedom (DOF) operation and commonly suffer from coupling errors, which restrict their applicability. This work presents a two-DOF piezoelectric (PZT) microgripper, in which PZT ceramic plates are bonded to the compliant mechanisms for actuation, and two-stage lever mechanisms are employed for displacement amplification, with one side generating gripping displacement and the other producing rubbing displacement. To address the coupling issue, three types of flexure hinges and their geometric parameters are theoretically analyzed and compared. The active compensation modules are incorporated into the structure, where compensation PZT plates combined with closed-loop control dynamically adjust the coupled displacement, thereby effectively suppressing coupling errors. Experimental results confirm that the proposed microgripper achieves two-DOF operation at nanoscale resolution, with coupling ratio minimized to only 0.09%. Moreover, its performance is further validated through experimental demonstrations, highlighting its effectiveness in complex micromanipulation operations.