Investigation of Ring Touch Mode Capacitive Pressure Sensor With an Electrothermomechanical Coupling Contact Model

Abstract

Ring touch mode capacitive pressure sensor, characterized by ring stopper and stepped circular diaphragm, is developed to eliminate or greatly alleviate some disadvantages existing in conventional or small-area touch mode capacitive pressure sensor. An electrothermomechanical coupling model is developed to calculate the deformation, stress and so on of the diaphragm, and it is universally available for different touch modes and non-touch mode. The model is with rapid calculation speed and it is verified by a combination of the finite element method (FEM) and boundary element method (BEM). Benefiting from the high calculation speed of the model, optimization designs of the sensor are carried out. By adjusting the height dimensions or radial dimensions, high sensitivity and strength can be achieved by such a sensor in different pressure ranges of interest without changing its planar package size and masks, or achieved in a very wide pressure range by an array composed of such sensors with a same set of process parameters of each sensor. On the other hand, optimal ratios of height dimensions or radial dimensions are acquired, which can suppress significantly the temperature’s influence on sensor operation, and furthermore, the optimal ratios are advisable for different pressure ranges and different material parameters of the sensor.