Shear deformation dominates in the soft adhesive layers of the laminated structure of flexible electronics

Flexible electronics has attracted much attention in recent years due to the favorable applications to many emerging devices. A novel laminated structure for a new-generation of flexible electronics is composed of several thin layers where the hard functional components are built glued by soft adhesives. To prevent the premature mechanical failure and to achieve the best performance of the electronics the structural design of such a laminate is of crucial importance. Accordingly it is necessary to establish an analytic model to accurately describe the mechanical behavior of the laminated structure. The available models fall into two categories: those only taking into account the normal strain-induced deformation of the soft adhesive layers and those only incorporating the shear deformation of the same layers. This paper aims to quantitatively figure out which deformation dominates. By establishing an accurate enough analytic model a significant finding is revealed that shear deformation dominates in the soft adhesive layers of the laminated structure of flexible electronics while the normal strain-induced deformation is negligible. The model is Well validated by the finite element method (FEM). The effects of the membrane energy and bending energy of the soft layer are also investigated by incorporating or neglecting the shear energy. The model accurately captures the key quantities such as the strain distribution in each layer and the locations of the neutral mechanical planes of the top and bottom layers. This work is expected to provide the design guidelines for the laminated structure-based flexible electronics. (C) 2016 Elsevier Ltd. All rights reserved.</p

Rotation-Facilitated Rapid Transport of Nanorods in Mucosal Tissues

Mucus is a viscoelastic gel layer that typically protects exposed surfaces of the gastrointestinal (GI) tract, lung airways, and other mucosal tissues. Particles targeted to these tissues can be efficiently trapped and removed by mucus, thereby limiting the effectiveness of such drug delivery systems. In this study, we experimentally and theoretically demonstrated that cylindrical nanoparticles. (NPs), such as mesoporous silica nanorods and calcium phosphate nanorods, have superior transport and trafficking capability in mucus compared with spheres of the same chemistry. The higher diffusivity of nanorods leads to deeper mucus penetration and a longer retention time in the GI tract than that of their spherical counterparts. Molecular simulations and stimulated emission of depletion (STED) microscopy revealed that this anomalous phenomenon can be attributed to the rotational dynamics of the NPs facilitated by the mucin fibers and the shear flow. These findings shed new light on the shape design of NP-based drug delivery systems targeted to mucosal and tumor sites that possess a fibrous structure/porous medium