Vibration-powered pressure sensor

Abstract

We propose a new concept of vibration-powered pressure sensor that enables pressure monitoring for downhole applications at multiple locations using optical interrogation. The sensor utilizes ambient mechanical energy to excite a resonating silicon structure that consists of a doubly supported beam with a proof mass at the center. One support of the beam is attached to a pressure diaphragm. The pressure-induced bending of the diaphragm produces an axial force in the beam, which alters the stiffness, and hence the resonant frequency. This results in a modulation of the resonant frequency by the input pressure. The frequency responses of the sensor driven by white- and colored-noise excitations are simulated numerically using a lumped model and by solving stochastic differential equations. The fmite element method is used for mechanical analyses. Simulations show that the highest sensitivity (330Hz/bar) is achieved when the beam support on the diaphragm is located at a distance of 0.6 times the radius from the diaphragm center. The sensitivity is approximately zero when the beam support is located at the diaphragm center. The induced principal stresses are below 400 MPa. The sensor does not require electrical power.