Design of Mechanical Failure Criterion for Living Human Tissue

Student thesis: Master thesis (including HD thesis)

  • Daniel Sean Gibson
4. term , Design of Mechanical Systems, Master (Master Programme)
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.
Publication date2017
ID: 258879207