A new design paradigm for micro-electro-mechanical systems and investigations on the compliant mechanisms synthesis.

Abstract

The multi-disciplinary field of Micro-Electro-Mechanical Systems (MEMS), makes possible the integration of mechanical and electrical elements at micron scale and their simultaneous fabrication using IC Chip-based microfabrication processes. The limited capabilities of such micromachining processes give way to new exigencies in design and manufacture such as restriction to a few layers and batch-production with minimal or no assembly at all. To surmount these difficulties, this research advocates the use of joint-less, assembly-free, almost frictionless single-piece compliant mechanisms for micro-applications. Compliant mechanisms are capable of generating a wider variety of motions than possible with simple beams and diaphragms that are widely used in MEMS today. Compliant mechanisms are a new breed of mechanisms in which elastic deformation is an intended source for motion and force transmission. Compliance can exist in discrete form, as with flexural pivots or can be distributed to make the whole mechanism flexible. The unitized construction makes the manufacture extremely simple at both micro and macro levels, and such compliant mechanisms are perfectly suited for any scale. To use distributed compliant mechanisms as superior substitutes for multi-membered mechanisms, it is necessary to generate a suitable structural form to perform the same function as the latter. There is no known previous attempt in this direction. The functional specifications are abstracted here as forces and deflections at the input and output points in the design continuum, and an optimal topology is sought to fulfill the design objective. Different formulations that capture the design intent of flexibility to engender motion and rigidity to sustain loads are proposed and numerically implemented by adapting an existing homogenization method (Bends/ore and Kikuchi) originally developed for structural design. The feasibility of the design method is demonstrated by fabricating compliant mechanisms at both micro and macro levels. When the objective of this research is fully accomplished, it will be possible to design single-piece compliant mechanisms in a single phase from-function-to-fabrication for usage at micro, meso, and macro scales.