Kho, Chun Min (2018) Development Of Transport Phenomena Mathematical Models For Linear And Concentric Microdialysis Probes With Diffusion Limited And Convection Enhanced Operational Features. PhD thesis, Universiti Sains Malaysia.

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Abstract
Microdialysis is a wellknown sampling technique in medical researches, most commonly used to measure the concentration of chemicals in the extracellular space of tissues. However, despite being a wellestablished technique, microdialysis often gives inconsistent amounts of chemicals collected from the sampling site (i.e. recovery). This would give rise to other complications, such as the requirement of preruns and calibrations. In order to resolve this issue, it is necessary to understand the mass transport limitations of microdialysis setup, by scrutinizing how each operational and design parameters of the microdialysis setup affect the recovery. One common approach is through mathematical modelling. Although there are already several mathematical modelling works on microdialysis, those works would focus only on providing accurate estimations of the recovery, while other features such as fluid flows are neglected. The main objective of this research work is to develop finite element mathematical models that could provide accurate simulations of concentration and fluid flow profiles for microdialysis. These models were constructed based on linear and concentric microdialysis probes. Modelling domain of these mathematical models would focus on the microdialysis probes, the membrane attached to the probes, and the probe surrounding area (PSA). The PSA for this research work is a quiescent medium filled with the analyte to be recovered, which is glucose. Mass transport properties in the models are represented by convectiondiffusion equations, while fluid flows are represented by NavierStokes equations. It is shown that the developed mathematical models could produce simulated recoveries that are comparable to experimental recoveries. Regression analysis between the simulated recoveries and experimental recovery gives Rsquared values of ≥ 98.5% for each model. Using these mathematical models, the advantages and drawbacks of altering the operational and design parameters for microdialysis setup were scrutinized. For instance, microdialysis sampling of glucose under perfused solution flow rate of 1.0 μL min1 using commercially available liner probe and concentric probe (10 mm membrane length, 30 kDa molecular weight cutoff) yield recovery of 30.98% and 36.67%, respectively. Reducing the perfused solution flow rate to 0.5 μL min1 would increase the recovery to 55.77% and 60.72%, respectively. However, at the same time, the temporal resolution of the microdialysis samplings was also greatly increased. In addition, although microdialysis is traditionally defined as a diffusionlimited process, it is shown in this work that under combinations of high perfused solution flow rate in the probe, high membrane porosity, and large membrane pore diameter, the influence of convective flux on the recovery of microdialysis sampling would be significant. In this case, convectionenhanced diffusion equations are necessary to represent the mass transport phenomena across the membrane attached to microdialysis probes.
Item Type:  Thesis (PhD) 

Subjects:  T Technology T Technology > TA Engineering (General). Civil engineering (General) > TA401492 Materials of engineering and construction. Mechanics of materials 
Divisions:  Kampus Kejuruteraan (Engineering Campus) > Pusat Pengajian Kejuruteraan Bahan & Sumber Mineral (School of Material & Mineral Resource Engineering) > Thesis 
Depositing User:  Mr Mohamed Yunus Mat Yusof 
Date Deposited:  02 Oct 2020 07:41 
Last Modified:  22 Oct 2020 03:03 
URI:  http://eprints.usm.my/id/eprint/47431 
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