A Three Degree-of-Freedom Model for Self-Retracting Fully Compliant Bistable Micromechanisms

Abstract

A three degree-of-freedom (3DOF) pseudo-rigid-body model (PRBM) has been developed and used in the design of a new class of self-retracting fully compliant bistable micromechanism (SRFBM). The SRFBM provides small-displacement linear travel bistability and is suitable for low-power microswitching applications. The design process involved a combination of single and multiple degree-of-freedom PRBM and finite element models to quickly proceed from a concept rigid-body mechanism to fully compliant fabrication-ready geometry. The 3DOF model presented here was developed to more accurately model the behavior of the tensural pivots—a new class of compliant segment used to avoid combined compressive loading of flexible segments. Four SRFBM designs were fabricated and tested for bistability, on-chip actuation, critical force, and fatigue tests. These tests validate the models used in the design process and demonstrate the functionality and reliability of the SRFBM.