This work considers the reliability of surface microfabricated structures and particularly the dynamic response of structural layers during operations, in order to develop a statistical modelling of failure mechanisms for micro-actuator. In situ test benches have been designed and fabricated allowing to applied elementary solicitations (traction, bending and torsion) to representative samples. Gold, in situ doped polysilicon and polysilicon doped by diffusion are used as structural layers. These devices are useful to study the fatigue phenomenon. Characterization and fatigue tests have been performed in a vacuum chamber under different environmental and stimuli conditions. Moreover, a theoretical analysis using Finite Elements Method has been achieved