Evaluation of Methodology to Make Radially Heterogeneous Blood Vessel Imitating Structures Using Polydimethylsiloxane
De Los Santos, Glen J
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This work focuses on forming a synthetic blood vessel imitating structure using a biocompatible polymer to mimic the multi-layer mechanical properties of native arteries with radial heterogeneity. The main contribution is a novel experimental protocol that will enable future implementation of theoretical blood vessel mechanics. Most important to this application are that the concentric layers of the blood vessel wall have different mechanical properties. Polydimethylsiloxane (PDMS) is a mechanically tunable, biologically inert, silicone based polymer widely used in biomedical laboratories. The project began with mold development and design, continued to polymer preparation techniques, then sample production, and finished with sample testing, analysis, and data comparison. A production polymer protocol was tailored to ensure that the samples were consistent, multi layered, and semi-transparent. All samples were tested in a Biaxial Vascular Testing and Culturing Device (BVTCD). This device placed the samples under physiological temperature and hemodynamic conditions and stretched them axially and circumferentially. The circumferential tests were conducted for a range of transmural pressures (0-300 mmHg) at three different axial stretch lengths. Pictures of each sample were taken at every pressure increment and processed digitally using MATLAB to determine stretch changes. Force values were measured and recorded for each stretch increment during the axial tests. The results were analyzed and compared to natural tissue samples taken from a bovine carotid. The samples were mechanically characterized and was found to have higher stiffness than natural blood vessels. The protocol developed proved to be effective in producing radially heterogeneous layered PDMS samples with degassing methods that provided clarity throughout the structure.