Analysis on microfinger with grooved patterns and its application in electric-thermal microgripper

The properties of a microfinger with groove patterns etched on its surface were discussed in this paper. An analytical model of the deflection was built up to study the effect of the groove size on the bending stiffness and the deflection of the grooved finger. The calculation of the analytical model is consistent with the simulation and experimental results. When the grooves depth is 0.5 μm, the spring constant of grooved microfinger is 22.8%, smaller than that of flat finger without grooved patterns. The spring constant of the finger decreases with the increasing of the depth of the grooves. A stable novel microelectric-thermal gripper is introduced based on the grooved finger. It consists of four sub-cantilever beams positioned at the diagonal lines of a square frame in the end of the main cantilever structure suspended from the silicon substrate, which guarantees an effective contact by the four-point contact area on the top surface to grab components of importance. The thermal-expansion-induced deflection makes the fingers moving vertically from an "open" position to a working one. The grooved finger helps to decrease the bending stiffness of the finger and increase the deflection and the initial gap. The simple fabrication process has a feasibility of compatible and mass production.