Design and Modeling of a Chevron MEMS Strain Sensor With High Linearity and Sensitivity

Abstract

Two new physical designs for sensors that can be used for strain measurement in large structures, such as bridges, wind turbines, or airplanes, are presented. While the proposed sensor designs focus on high sensitivity, they are based on simple operating principle of comb-drive differential variable capacitances and chevron displacement amplification. The chevron beams convert small amount of applied strains to measurable changes in capacitance of comb fingers. The design of the structures enables simple fabrication methods for the realization of the sensors. Two designs are proposed with the first design can also be used as a sensitive resonant strain sensor. Device performances are validated both by analytical solutions and also by finite-element method simulations. The obtained nominal capacitance is 25 fF, with sensitivities of 13 and 2.7 aF per microstrain ( $\mu \varepsilon$ ) while demonstrating a maximum strain range of ±1000 and $\pm 1800~\mu \varepsilon $ , respectively, for the first and second designs. As a resonant strain sensor, the first design exhibits a sensitivity of $\sim 8.6$ Hz/ $\mu \varepsilon $ .