Analyzing the effect of existing bubbles in the interface liquid on the dynamic response of the strain-gauge type pressure sensor

Abstract

This paper studies one of the major failures, that may occur in macro-scale strain gauge pressure sensors as well as micro-scale ones. The leakage in the interface fluid chamber of the sensor causes the air to be trapped especially in the form of bubbles in the interface liquid near the boundaries. In this work, mathematical modeling of a strain gauge pressure sensor in the presence of the trapped micro-scale bubbles in the interface liquid is presented. The governing equations of displacement of the membrane and sensing plate coupled with the nonlinear dynamic equation of bubbles are solved simultaneously utilizing the Galerkin weighted residual method. The transient response of the sensor in the presence of bubbles is investigated considering different types of applied dynamic pressure as step, single pulse, repetitive pulse, and harmonic. Results indicate that when a higher percentage of the interface oil is filled with bubbles, the maximum overshoot in the response of the sensor reduces, while, the peak time, rise time, and also settling time in the response of the sensor increases. A delay is observed in the time-domain response of the sensor due to the reduction of speed of transferring data from the membrane to the sensing plate caused by the bubbles in the interface liquid.