Double-Proof Mass SOI-Based Matryoshka-Like 3-Axis MEMS Accelerometer

MEMS accelerometers have been around for many years and became a key element to different applications, such as inertial navigation, or geophysical sensing. Some of those applications require multi-axis sensing. To address the challenge of measuring accelerations in 3 axis with comparable transduction, a novel SOI-based 3 axis MEMS accelerometer based on hierarchical structures is presented, featuring only 2 pairs of differential parallel-plate electrodes for acceleration measurement and 4 surface micromachined membrane electrodes (for z-axis direction determination). Fabricated devices showed sensitivities larger than 30 mV/g in the 3 axes over a ±1 g range, proving that the proposed architecture yields working, sensitive devices, without the need for a dedicated set of electrodes for the out-of-plane component.