Antistiction Recoil Accelerometer

In this paper we describe a new MEM capacitive accelerometer architecture that is able to increase the robustness of the device from high-g shocks with respect to a conventional accelerometer. The concept is based on the recoil effect given by a 2 degrees of freedom mechanical structure. During an impact that goes beyond the accelerometer mechanical full scale, the displacement of the first mass, which houses the electrodes, is bounded by a set of physical stoppers. Instead, the recoil mass, linked to the sense mass through a rigid spring, stores extra potential energy. When the external acceleration is no longer applied, the retained energy in the stiff spring pushes back the first sense mass, thus helping it to detach from the stoppers. The proposed architecture was modelled through numerical simulations and verified thanks to an experimental campaign based on high-g shocks. The manufactured test structures showed a significant improvement in reducing the occurrence of adhesion phenomena.