Design of Mechanical Failure Criterion for Living Human Tissue

Gibson, Daniel Sean

4. term

Design of Mechanical Systems, Master

2017

2017-06-02

Numerous diseases are related to the breaking down of muscle tissues due to the effects of mechanical loading. Deep tissue pressure ulcers (PU) are one such disease that have a significant cost to patient welfare and high financial costs due to patient care and treatment. The disease can be difficult to detect until it reaches a severe state and is difficult to treat. A time-lapse experiment has previously been developed by Aalborg University alumni to investigate the effects of strain state on the rate of change of cell viability. The overall aim of the experiment is to develop a mechanical failure criterion for living human tissue. It is believed that through continued investigation into the effects of strains, specifically, shear strains, on living human tissue cells, evidence-based intervention methods can be put into place to reduce the risk of associated diseases. The experimental procedure captures image sequences to investigate the effects of strain on living tissue samples. A specially designed aluminium indenter is used to apply a load to the centre of a cell sample and the effects over a relatively large area are observed by capturing a sequence of images. The observations are repeated at regular time intervals over a period of approximately eight hours, as well as after twenty hours. The number of dead cells observed through cell staining techniques. This thesis documents the processes that have been undertaken to further develop the experimental set-up. Four experiments were undertaken and the results have suggested that mechanical loading has a significant effect on cell viability. Further work is needed to develop this. Of the four experiments undertaken, three of the experiments suffered from exposure problems or sparse cell samples which made the analysis processes difficult. The fourth experiment fixed all of these problems but was terminated prematurely due to a mechanical failure. Despite this, the experiments have demonstrated that, with some small refinements, the methods used in this thesis will be suitable for developing a mechanical failure criterion for living human tissue.

Mechanical ; failure criterion ; living tissue ; human tissue ; mechanical loading

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