E-Thesis 233 views 48 downloads
Ex vivo experimental investigations and modelling of the layer-dependent, anisotropic, visco-hyperelastic behaviour of the human oesophagus / Ciara Durcan
Swansea University Author: Ciara Durcan
DOI (Published version): 10.23889/SUthesis.66103
Abstract
As a mechanical organ, the material properties of the oesophagus are integral to its function. The quantification of these properties is necessary to investigate the organ’s pathophysiology and is required for a range of applications including medical device design, surgical simula-tions and tissue...
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Swansea, Wales, UK
2024
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| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | Ph.D |
| Supervisor: | Hossain, Mokarram ; Perić, Djordje |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa66103 |
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| Abstract: |
As a mechanical organ, the material properties of the oesophagus are integral to its function. The quantification of these properties is necessary to investigate the organ’s pathophysiology and is required for a range of applications including medical device design, surgical simula-tions and tissue engineering. However, according to a systematic review of mechanical exper-imentation conducted on the gastrointestinal organs, the discrete layer-dependent properties of the oesophagus have not been investigated using human tissue, especially regarding its vis-coelastic and stress-softening behaviour. Therefore, extensive experimentation was conducted to determine the time, layer and direction-dependent material response of the oesophagus us-ing cadaveric human tissue. The residual strains of the organ were also considered via opening angle experiments. Overall, the results showed distinct properties in each layer, highlighting the importance of treating the oesophagus as a multi-layered composite material. Furthermore, a strong anisotropy was exhibited across both layers, where the longitudinal directions were much stiffer than the circumferential directions. Due to the COVID-19 pandemic, fresh human cadavers were not available from the anatomy laboratory for a considerable amount of time. Therefore, mechanical testing was first completed on embalmed human tissue and then, once available, on fresh human tissue. This unforeseen circumstance, through comparison of the two preservation states, allowed for an interesting discussion on the role of the tissue’s con-stituents on its complex material behaviour. In addition, histological analysis was carried out to determine the density of the oesophagus’ most mechanically relevant fibres: collagen and elastin. This knowledge was then used to inform constitutive modelling of the soft tissue’s behaviour, the outcome of which was able to capture the anisotropy, visco-hyperelasticity and stress-softening observed in the experimental data. |
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| Keywords: |
Biomechanics, Soft tissues, Gastrointestinal tract, Constitutive modelling, Cadaver preservation |
| College: |
Faculty of Science and Engineering |