A new optimal design method for electrostatically actuated silicon-based MEMS: Application to a micro-gripper with large stroke and high force resolution

A. Grira (1) , C. Rotinat-Libersa (1) , Bernard Legrand (2, 3) , L. Buchaillot (2, 4)

1 DIASI (CEA, LIST) - Département Intelligence Ambiante et Systèmes Interactifs
2 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520
3 LAAS-MEMS - Équipe Microsystèmes électromécaniques
4 NAM6 - IEMN - Nano and Microsystems - IEMN

The design of Micro Electro Mechanical Systems (MEMS) is often based on the use of costly trial and error method which depends highly on the technical skills of the involved engineers. The drawback of such a procedure is to lead to sub-optimal designs and poor performance at the end. Some research works on dedicated optimization tools have begun a few years ago. The present paper deals with the development of a dedicated optimal design tool for monolithic MEMS, fabricated using the Silicon On Insulator (SOI) process. This tool is an evolution of a previously developed heuristic method, using a multi-objective evolutionary algorithm and a compliant building blocks library. It has been adapted and implemented in the MEMS design software called FlexIn SOI (Flexible Innovation for SOI), which account for the anisotropic elastic behavior of the Single Cristal Silicon material for the Finite Element evaluation of the fitness functions involved in the optimization process. To illustrate the usefulness of this tool, the automatic optimal design of a monolithic microgripper has been investigated. Here, the micro-fabrication process resolution is defined as an optimization constraint. Five dedicated objective functions have been considered to quantify real performances of the gripper, and also to be able to consider the use recommendations of associated inter-digital actuators and sensors. At the end of the optimization process, the nonlinear comb-drive actuator stiffness has been considered to select an electromechanically stable solution among Pareto front. This solution has been prototyped and characterized. It showed very outstanding performances regarding state-of-the-art micro-grippers [1], thus validating the proposed optimal design method.

Mots clés: MEMS; Optimal systems; Microgripper; Multi objective evolutionary algorithms; Non-linear stiffness; Optimal design methods; Silicon-on-insulator process; Electrostatic actuators; Trial-and-error method; Silicon; Silicon on insulator technology; Finite element evaluations; Micro electromechanical system (MEMS); Stiffness; Machine design; Heuristic methods; Anisotropy; Actuators; Genetic algorithms; Finite element method; Grippers

Domaines: Sciences de l'ingénieur [physics]

A. Grira, C. Rotinat-Libersa, Bernard Legrand, L. Buchaillot. A new optimal design method for electrostatically actuated silicon-based MEMS: Application to a micro-gripper with large stroke and high force resolution. 1st International Conference on Engineering and Applied Sciences Optimization, OPT-i 2014, Jun 2014, Kos Island, Greece. pp.2407-2417. ⟨cea-01844451⟩