A Planar Resonant Structure Sensitive to Out-of-plane Forces

Abstract

We present a novel force sensor designed to facilitate force measurement deployment in various applications such as load cells or force sensitive surfaces. This force sensor can indeed inherently sense out-of-plane forces. It is a monolithic structure that integrates two resonators and provides a steady area. If a perpendicular force is applied on this steady area, a frequency shift of the two resonators occurs. The amount of force applied can thus be estimated by monitoring the frequency of the resonators. As a proof of concept, we report the fabrication and experimental characterization of a first prototype. Under atmospheric pressures, our prototype currently offers a quality factor of ∼700, and a linear displacement sensitivity of ∼5.75Hz/μm. In addition, we report the implementation of a compact and low-cost optical fiber setup to monitor the resonators’ frequency.