Resonant pressure sensing using a micromechanical cantilever actuated by fringing electrostatic fields

Abstract

We demonstrate a pressure-sensing approach based on the resonant operation of a single-crystal Si cantilever positioned near a flexible, pressurized membrane. The membrane deflection perturbs the electrostatic force acting on the cantilever and consequently alters the beam's resonant frequency. Sensitivity was enhanced by tailoring the actuating force nonlinearities through fringing electrostatic fields. With our coupled micromechanical system, we achieved frequency sensitivity to pressure and displacement of ≈ 30 Hz/kPa and −4 Hz/nm, respectively. Our results indicate that the suggested approach may have applications not only for pressure measurements, but also in a broad range of microelectromechanical resonant inertial, force, mass and bio sensors.