Development of a two-stage amplification microgripper for high-precision applications

Microgrippers are precision actuation devices designed for the capture, release, and manipulation of microscale objects. The key challenge in achieving high-precision micro-grasping operations lies in suppressing the parasitic displacement of the gripping jaws. This paper proposes a two-stage amplification mechanism with low parasitic displacement to achieve high-precision micro-grasping operations of the microgripper. When the clamping displacement direction of the microgripper aligns with the desired motion direction, parasitic displacement is minimized. The second-stage amplification mechanism is directly connected to the microgripper's output end, which determines the magnitude of parasitic displacement. Among these, a symmetrical compound parallelogram mechanism with flexure hinges is introduced as the second stage to fundamentally minimize parasitic displacement. Simulation results show that the proposed externally actuated microgripper with displacement compensation achieves a parasitic displacement rate of only 0.158%. Experimental results demonstrate that under an air pressure of 0.6 MPa, the prototype achieves a total output displacement of 490.3 μm, a total amplification ratio of 29.1, and a measured first-order natural frequency of 1625 Hz. The experimental results validate the rationality of the design, indicating the potential of this microgripper for micromanipulation tasks requiring both a large stroke and high precision.