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Tissues and organs contain an extracellular matrix (ECM). In the case of blood vessels, endothelium cells are anchored to a specialized basement membrane (BM) embedded inside the interstitial matrix (IM). We introduce a multi-structural collagen-based scaffold with embedded microchannels that mimics in vivo structures within vessels. Our scaffold consists of two parts, each containing two collagen layers, i.e., a 3D porous collagen layer analogous to IM lined with a thin 2D collagen film resembling the BM. Enclosed microchannels were fabricated using contact microprinting. Microchannel test structures with different sizes ranging from 300 to 800 µm were examined for their fabrication reproducibility. The heights and perimeters of the fabricated microchannels were ~20% less than their corresponding values in the replication PDMS mold; however, microchannel widths were significantly closer to their replica dimensions. The stiffness, permeability, and pore size properties of the 2D and 3D collagen layers were measured. The permeability of the 2D collagen film was negligible, making it suitable for mimicking the BM of large blood vessels. A leakage test at various volumetric flow rates applied to the microchannels showed no discharge, thereby verifying the reliability of the proposed integrated 2D/3D collagen parts and the contact printing method used for bonding them in the scaffold. In the future, multi-cell culturing will be performed within the 3D porous collagen and against the 2D membrane inside the microchannel, hence preparing this scaffold for studying a variety of blood vessel–tissue interfaces. Also, thicker collagen scaffold tissues will be fabricated by stacking several layers of the proposed scaffold. [ABSTRACT FROM AUTHOR]

The aim of this study is to provide a coupled finite element–boundary element method approach for aeroelastic investigations in incompressible flow fields. Hence, an efficient and applicable tool for aeroelastic response computations is developed which uses boundary element method to solve flow fields and finite element method to analyze structural domains. In unsteady flow solution, the potential flow assumptions are considered, while the small deformations are assumed in structural dynamics behavior. Both solution procedures are tightly related by a boundary interface in a sequential coupling procedure. To illustrate the performance of aerodynamic solver for computation of three-dimensional unsteady flow configurations, lift response of a wing–body combination is computed and validated with available results in literature. Also, two test cases are presented that illustrate the accuracy of the developed tool for aeroelastic response analysis in comparison with available experimental results. [ABSTRACT FROM AUTHOR]