Novel image correlation based techniques for mechanical analysis of MEMS

Three techniques have been developed to analyze the mechanical behavior of micromechanical systems, in particular stretchable electronic interconnects. The techniques are all digital image correlation (DIC) based and vary in the type of images used for correlation and the way of regularizing the displacement field, needed because of the ill-posed nature of DIC problems. The first two techniques use Non-Uniform Rational B-Splines (NURBS) which are adaptively refined to autonomously obtain an optimized set of shape functions for the considered problem. The first method applies this to regular grayscale speckle images, while the second technique requires profilometric height images to calculate not only the in-plane deformation, but also the out-of-plane component of the displacement field. The third method is an integrated DIC approach and is coupled to a finite element (FE) model of the sample for regularization of the displacement field. It correlates projections of the sample contour rather than a speckle pattern, which makes the method suitable for large, complex and three-dimensional displacements and cases where speckle pattern application is difficult, such as microscale samples. Application of the techniques to i.a. stretchable electronic interconnects yields good results.