Advanced models for the calculation of capillary attraction in axisymmetric configurations

The proper estimate of capillary attraction is of great importance in many situations, for example the reliability assessment of Micro- Electro-Mechanical Systems (MEMS) with respect to spontaneous adhesion. In spite of many theoretical studies, there is a lack of general methods for obtaining the exact shape of the liquid meniscus between the asperities of rough surfaces. In this paper, a new analytical method is developed for the specific case of axysimmetric configurations. The outcomes of such a method are critically compared with the approximate solution which is usually proposed in the literature. Moreover, an improved simplified method is constructed and validated. Finally, a more general procedure (based on the Finite Element Method) is proposed, with possible application to nonsymmetric geometries.