Design, kinematic modeling and performance testing of an electro-thermally driven microgripper for micromanipulation applications

Abstract

Microgripping systems incorporate miniature end-effectors used to manipulate micro-sized objects such as tiny mechanical parts, electrical components, biological cells and bacteria. This paper presents a thorough study of the design, kinematics and static/dynamic performances, including electro-thermo performance characteristics, of the new microgripping system. The developed microgripper had a monolithic design which consisted of a combination of an in-plane electro-thermally driven microactuator and a compliant tweezing mechanism. The kinematics of the microgripper was studied as a transformation of input linear actuation motions into output tweezing displacements and compared with microgripper prototypes fabricated from 25 µm thick nickel foil by using laser micromachining technology. The static, dynamic and electro-thermal characteristics of the system performance were analyzed with respect to actual actuation motions, tweezing displacements, voltage, power, electric resistance and overall temperature under constant applied current within a range of {20, 40, …, 160} mA. Maximum tweezing displacements of 47.5 µm (tweezing gap of 94.9 µm) were achieved under an applied current of 160 mA for a fabricated microgripper having a transform coefficient K = 1.731. The repeatability and reliability of the fabricated microgripper were also tested along with the capability to grip, hold and release a 110 µm diameter glass bead proving that this microgripper can be utilized as a grasping end-effector for micromanipulation, microrobotic and microassembly applications.