Study on the Grooved Finger and its Application in Micro Gripper

Abstract

A micro grooved finger has smaller bending stiffness and can be used to improve the performance of some micro cantilever devices. The deflection and bending stiffness of a micro grooved finger are discussed in this paper. An analytical model of the deflection is built up to study the effect of the groove sizes on the bending stiffness and the deflection of the grooved finger. The calculation of the analytical model is consistent with the simulation and experiment results. When the grooves depth is 0.5 μm, the spring constant of grooved micro finger is 19.8% smaller than that of flat finger without groove patterns. The spring constant of the finger decreases with the increasing of the width and depth of the groove. A novel micro electric-thermal gripper is introduced based on the grooved finger. It consists of four sub-cantilever beams arranged at the diagonal lines of the 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 object of importance. The thermal expansion induced deflection makes the fingers moving vertically from an ‘open’ position to a working one. The grooved fingers help 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.