Micromachined Capacitive Sensor With Configured Boundaries: Approach, Design and Fabrication

A new set of capacitive-based resonators is introduced in this work that utilizes a unique configured boundaries approach. The proposed design strategy is utilized to develop and characterize three circular resonators as proof-of-concept with strategically configured boundaries. For a fair comparison, the introduced novel resonators along with a reference conventional structure are fabricated using a commercially available fabrication technique, PolyMUMPs. The effects of the presented approach on plate deflection and electromechanical coupling coefficient are demonstrated through finite element analysis (FEA) using COMSOL Multiphysics as well as experimental characterizations. The fabricated devices are electrically evaluated. The white light interferometry is further used for deflection measurements. The device performance evaluations illustrate a robust control of the resonator’s plate stiffness and deflection while maintaining the same dimensions. Experimental evaluations demonstrate an enhanced deflection profile of the plate, which significantly increases the average deflection by up to 50% compared to the conventional resonator developed with the same dimensions and fabrication process. Furthermore, it is observed that using the proposed approach reduces the pull-in voltage by up to 17% compared to the conventional resonators while preserving the resonant frequency within
$\pm$
150 kHz.