Session: Research Posters

Paper Number: 118567

118567 - Computational and Experimental Characterization of Functionally Gradient Tissue Scaffolds for Complex Loading Conditions 

Structures with Triply Periodic Minimal Surfaces (TPMS) have gained significance for diverse applications in biomedical engineering, including tissue engineering scaffolds, implant coatings, drug delivery systems, and biosensors. For example, TPMS bone tissue scaffolds possess interconnected pores and a large surface area, which can facilitate cell adhesion, proliferation, and nutrient diffusion. To enhance the biomimetic nature of these TPMS scaffolds, functional gradients such as pore size and porosity variations are often incorporated into these structures. While functionally gradient scaffolds have been shown to achieve better bone regeneration outcomes, variations in their pore size and porosity distributions can significantly influence their mechanical behaviour, which needs to be carefully considered when designing these structures for load-bearing applications. Recent studies have investigated the mechanical characteristics of functionally gradient scaffolds under axial loading. However, bone scaffolds usually undergo far more complex loading conditions, including compression, shear, and torsion. Hence, the mechanical behaviour of these scaffolds must be investigated in various loading scenarios to ensure their efficacy in real-world applications.

This study combines computational modelling with experimental characterization methods to systematically investigate the mechanical properties of functionally gradient TPMS structures in various loading conditions. Two different TPMS scaffolds, including gyroid and primitive, are designed with various porosity distributions while the overall porosity is kept constant between all groups. Finite element analysis (FEA) is conducted on each scaffold with a cylindrical shape to evaluate their stress distribution, stiffness, and strength under three different loading scenarios, including compression, shear, and torsion. To validate the FEA results, the scaffolds are fabricated from a biocompatible Acrylonitrile butadiene styrene (ABS) material by a 3D printing technique named PolyJet™ technology. Then, in-house experimental mechanical tests are conducted on the scaffolds using customized jigs to replicate the loading conditions used in the FEA simulations.

The computational results indicate that a decrease in the porosity of the scaffolds toward their centre can significantly enhance their stiffness and strength compared to scaffolds with the same overall porosity and non-gradient pore distribution. Moreover, it is demonstrated that a sharper decrease in porosity can further increase the stiffness and strength of the scaffolds. Furthermore, the FEA results are validated through comparison with our in-house experimental data obtained from the compression, shear, and torsion testing on the scaffolds.

This study concluded that TPMS structures with functionally gradient pore size and porosity could significantly improve the mechanical properties of bone scaffolds in complex loading conditions. Moreover, the rate of variation in the pore size and porosity could further control the mechanical behaviour of these porous structures. This study is expected to provide significant insight into the design and optimization of functionally gradient structures for applications in tissue engineering and prosthetic devices.

Presenting Author: Ali Entezari University of Technology Sydney

Presenting Author Biography: Dr Ali Entezari is a Lecturer within the School of Biomedical Engineering at the University of Technology Sydney. Dr Entezari received his PhD from The University of Sydney. He is the recipient of three prestigious international fellowships, including a Fulbright Postdoctoral Fellowship, a Humboldt Research Fellowship, and a Marie Skłodowska-Curie Postdoctoral fellowship.

During his postdoctoral appointment at the University of Sydney, he collaborated with the industry to develop novel 3D printed orthopaedic implants. Dr Entezari’s primary research interests include biomechanics, tissue engineering, computational mechanics, additive manufacturing, and medical device development.

Authors:

Ali Entezari University of Technology Sydney
Chi Wu University of Sydney
Qing Li University of Sydney