Micro - Architectural Data Extraction for Electrospun Poly (Ester Urethane) Urea Scaffolds for Biomechanical Modeling.

Problem: Soft tissue engineered applications have raised the need for accurate descriptions of tissue microstructure and their contributions to global mechanical behavior [1]. Accurate material image analysis is crucial to model engineered tissue biomechanics. The present study proposes a novel method to automatically collect micro-architectural data from electron micrographs (SEM) of electrospun poly (ester urethane) urea (PEUU). Methods: Sets of contiguous SEM images for electrospun PEUU scaffolds made using three mandrel collection tangential velocities (1.5, 4.5, 9.0 m/s) were analyzed. A combination of thresholding and morphological procedures enabled overlaps of fibers to be detected. The algorithm detection 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 performing the image analysis over material areas of different sizes. Results: The number of overlaps, the total number of connections and the estimated porosity all decreased as the mandrel velocity was raised. Fiber orientation results were consistent with previous findings [1]. The RVE size increased as the mandrel velocity increased consistent with a higher degree of structural organization and fiber alignment. The number of fiber overlaps was predicted for a given mandrel velocity and scaffold area. Conclusions: The detected fiber overlaps, connectivity and angle distribution showed consistency with the known relationship between mandrel velocity and fiber alignment. The extracted data are considered to be highly relevant for electrospun PEUU scaffolds and collagenous tissue biomechanical modeling. The proposed approach enables a detailed analysis of the micro-architecture to be performed on electrospun PEUU scaffolds. References: 1) Courtney et al. Biomaterials 2006. 27, 3631-3638. Acknowledgements: The authors would like to acknowledge financial support from the NIH grant R01 HL-068816. Disclosures: None of the authors have financial interests related to the topic of the abstract.