Designing a 100 [aF/nm] capacitive transducer

The mechanical part of inertial sensors can be designed to have a large mechanical sensitivity, but also requires the transduction mechanism which translates this displacement. The overall system resolution in mechanical inertial sensors is dictated by the noise contribution of each stage and the magnitude of each sensitivity, see also Figure 1. Maximizing the capacitive sensitivity, results in suppression of noise in the electronics domain. This work focuses on the design and realization of a mechanical to electrical transduction using a capacitive readout scheme. Design considerations and measures are taken to maximize the latter are considered and illustrated using FEM simulations. A capacitive transducer showing a sensitivity of 100 [aF/nm] was designed and realized, by exploiting the large displacement behavior of the inertial sensor which was considered.