Bistable In-Plane Switching by a Ni-Ti-Cu/Si Microactuator

This paper introduces a novel concept of in-plane bistable switching of a freely suspended Si platform using a co-integrated Ni-Ti-Cu/Si micro-actuator with large stroke. The microactuator consists of two coupled prestrained Ni-Ti-Cu/Si beams with nano-scale hinge dimensions, which are designed to exhibit buckling instability. By selective Joule heating, the one-way shape memory effect in the Ni-Ti-Cu layer results in a large shape recovery force allowing to switch between the stable states. First, we show the model-based design of the bistability range and switching force. Then, we present a process flow for co-integration onto a Si photonic chip for optical waveguide switching and demonstrate mechanical switching performance by in-situ experiments in a SEM.