Computational mechanical characterisation of Schwarz P unit cell-based tissue scaffolds fabricated via two-photon polymerisation

Zabidi, Adi Zakwan (2019) Computational mechanical characterisation of Schwarz P unit cell-based tissue scaffolds fabricated via two-photon polymerisation. PhD thesis, University of Nottingham.

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Abstract

Schwarz P unit cell-based tissue scaffolds have been fabricated via two-photon polymerisation (2PP). In this thesis, a computational approach to characterising the mechanical properties of the scaffolds made of poly(D,L-lactide-co-ε-caprolactone)(PLCL) copolymer via micromechanical analysis is presented.

The stereolithography (.STL) model of the Schwarz P unit cell design used as input for 2PP was ‘reverse engineered’ to obtain a surface geometry model for implementation in computational analyses. In the experimental model of this study, the mechanical properties of bulk material PLCL and fabricated tissue scaffolds were experimentally characterised. Data obtained from fabricated tissue scaffolds were used as a basis of comparison to data obtained from mechanical characterisation of the scaffold via computational analyses.

Computational model of this study involved the implementation of micromechanical analysis together with the Schwarz P surface geometry model and bulk material data obtained previously in linear and non-linear analyses. Initial investigations in linear analyses showed significant discrepancy between the experimental and computational model due to geometrical transformations between the input Schwarz P unit cell design and unit cells comprising the fabricated tissue scaffolds. This was confirmed further through measurement analyses of scanning electron microscope (SEM) micrographs of the scaffolds. A methodology to mediate the geometrical transformations through CAD modeling techniques was investigated before re-implementation into revised linear analyses. Results showed excellent agreement between the computational and experimental results with only a small margin of error at 6.94%. Investigations in non-linear analyses demonstrated parallels between stress-strain response obtained from micromechanical analysis and those from in vivo loading conditions in confined compression of Schwarz P unit cell-based tissue scaffolds. Implementation of micromechanical analysis to oversee relationships between different dimensional parameters to the resulting effective modulus was also investigated through linear analyses. Mathematical expressions describing the relationships were then derived.

This thesis concludes with the implications of this study with suggestions for improvement. Suggestions for future work are also put forward.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Scotchford, Colin A.
Grant, David
McNally, Donal S.
Keywords: tissue scaffolds; Schwarz P unit cell-based tissue scaffolds; two-photon polymerisation
Subjects: R Medicine > R Medicine (General) > R855 Medical technology. Biomedical engineering. Electronics
Faculties/Schools: UK Campuses > Faculty of Engineering
Item ID: 56230
Depositing User: Zabidi, Adi
Date Deposited: 18 Jul 2019 04:40
Last Modified: 07 May 2020 12:01
URI: http://eprints.nottingham.ac.uk/id/eprint/56230

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