Compliant Mechanisms for MEMS and Flexonics

Summary form only given. A continuum compliant mechanism transmits applied forces from specified input ports to output ports by elastic deformation of its comprising materials, fulfilling required functions analogous to a rigid-body mechanism. It has a large range of applications in both micro and macro domains. This presentation describes a level-set method for designing monolithic mechanisms with distributed compliance and/or made of multiple materials. Central to the method is a level-set model that precisely specifies the distinct material regions and their sharp interfaces as well as the geometric boundary of the structure, capable of performing topological changes and capturing geometric evolutions at the interface and the boundary. Techniques for eliminating de facto hinges and for geometric control in the design are discussed, aiming at producing more reliable compliant mechanism designs for MEMS devices. We further discuss the intrinsic deficiencies in the widely used "spring model" and propose a new formulation considering the "characteristic stiffness" of the mechanism. The result is a design with highly even-distributed compliance and a more desirable characteristic, which uniquely distinguishes our method. These methods are demonstrated with benchmark examples of both structure optimization and compliant mechanism optimization. The compliant mechanisms are intended for the use in automated assembly of hybrid MEMS with self-alignment techniques to eliminate tight positioning requirements.