In this work two new compliant MEMS designs are introduced. The first one is a fully compliant mechanism consist of snap-through buckling arcs. The second one is a compliant bistable mechanism making use of buckling beams. These compliant mechanisms incorporate large deflecting arcs and beams, and a shuffle or a slider. The kinematic simulation of these novel mechanisms are studied using nonlinear Elastica theory, and numerically solving the nonlinear algebraic equations. The large-deflection analysis of the flexible snap-through buckling arc beams and pin-pin buckling beams are utilized using polynomials fits to exact Elastica Solution. The normalized kinematic responses of both mechanisms are investigated. Some of the crash test impact loadings in literature are reviewed in details. The nonlinear equation of motion including the inertia of shuttle, and the stiffness obtained from Elastica theory is simulated for an example pulse impact loading using numerical Runge-Kutta methods for Design L These compliant MEMS are suitable for crash detections and can be fabricated with the integrated circuit on the same board to be used for Intelligent Safety Systems.