Design and simulation analysis of a cylindrical shell capacitive pressure sensor for noninvasive measurement of low pressure
摘要
Capacitive pressure sensors (CPS) have several applications and are widely used for pressure measurement. However, they have a significant disadvantage in terms of sensitivity versus dynamic range trade-off. Mostly, it is crucial and challenging to use CPS for noninvasive assessment of low pressure in medical flexible tubings. Diaphragm displacement of flat plate sensors due to a radial displacement of a fluid catheter is small. This makes the sensor insensitive because the transmission mechanism might not amplify the input displacement for minute but significant loads. Additionally, the dynamic range and sensitivity are reduced because of the small contact surface area between the catheter and a flat plate diaphragm. To address these challenges, we design and analyze a novel type of sensor, namely, the cylindrical shell capacitive pressure sensor (CS-CPS). CS-CPS allows increased contact surface area between the sensor and flexible tubings, thus enhancing input displacement, sensitivity, and simplicity of integration with flexible tubings. The sensor is designed and simulated in COMSOL Multiphysics. The finite element analysis method is utilized to analyze the diaphragm deformation and capacitance variations in response to pressure. For verification purposes, we do a mathematical analysis in MATLAB using the derived deformation and capacitance variation formulae. Compared to the flat plate sensor, the newly designed sensor achieved an increased diaphragm displacement of 2.49x10