A Microgripper with a Large Magnification Ratio and a High Structural Stiffness Based on a Flexure-Enabled Mechanism

This paper presents a novel piezoelectric-actuated microgripper that mainly consists of a three-stage flexure-based amplification mechanism to achieve a large magnification ratio, a high structural stiffness and a great force output capacity for micromanipulation and assembly. The first two stages are configured as two bridge-type parallelogram amplification mechanisms connected in serial to provide advantages in terms of high structural stiffness and compactness. This configuration is capable of generating large forces to maintain the following connection leverage mechanism and ensure a large displacement output, and also produces a stable amplification ratio insensitive to the input change. The finite element method (FEM)-based simulation has been performed to investigate both static and dynamic characteristics of the designed microgripper. Simulation-enabled structural optimization design has been implemented to further aid and improve the proposed design. The simulation results indicate that the amplification ratio reaches 30.66 with a maximum clamping force of up to 2.32N. The gripper prototype has been fabricated based on the wire electro discharge machining technique, and its performances have been validated through pack-and-place of microbeads experiments. The experimental results have demonstrated its excellent linear amplification performance and they match well with the outcomes from both simulation and theoretical calculation in terms of motion range and amplification ratio.