Micro Scale Based Mechanical Models for Electrospun Poly (Ester Urethane) Urea Scaffolds

Micro scale based mechanical models can provide a tool to guide tissue engineering scaffold design and to investigate on how the cellular mechanical and metabolic response are related to local micro-structural deformations. The present study proposes a novel approach to automatically collect micro-architectural data from SEM images of electrospun poly (ester urethane) urea (PEUU) and to recreate statistically equivalent scaffold mechanical models. Sets of contiguous SEM images for each of the three mandrel velocities (1.5, 4.5, 9.0 m/s) were analyzed. A combination of thresholding and morphological procedures enabled fibers overlaps to be detected. The algorithm precision was tested on regular grids of known characteristics. A modified Delanauy network was generated starting from the detected 2D fiber overlap coordinates. The following micro-architectural data were extracted from the generated network: (1) fiber overlap number and position, (2) connectivity distribution, (3) fiber angle distribution. Appropriate representative volume element (RVE) size was determined. A finite element model of the meso scale system (250 x 250 µm) was constructed respecting the micro-architectural data characterized by the image analysis. FEM and image analysis results revealed the capacity of the approach to characterize the material mechanical behavior at both the fiber and the global levels.