Design of microfluidic system for handling biological samples

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Dr. Gordon Péter Róbert
Department of Electronics Technology

In my Thesis I have analyzed the designing process of a microfluidical unit that is able to separate the plasma and the blood cells. In everyday medical practice there is a growing need for devices that are able to analyze small samples away from the clinical surrounding without requiring professional staff. Towards fullling these aims microfluidical devices are needed. In most of the clinical experiments plasma seperation is one of the rst steps of the procedure. For a more effective and quicker diagnosis, this function is inevitable for designing a more and more widely spread lab-on-a-chip.

In the present work I deeply examined the literature dealing with microfluidical solutions that are able to separate cells. I invented a check list with the help of which I could chose the convenient method for separation. Separation based on the Zweifach-Fung ffect could be examined by designing special microstructures. As the relevant literature is not dealing with structure designing throwloughly, therefore, I designed an experiment for measuring the effects of the relevant geometrical parameters on the separation mechanism. For constructing the microfluidical test structure we used the MEMS laboratory of the Research Institute for Technical Physics and Materials. First time I have constructed the microfluidical system in silicone-glass structure. For building the silicon slices deep reactive-ion etching were used, while the glass sandwich structure was treated with a frequency tripled Nd:YAg laser for building the joint surfaces. With the anode bonding of the two surfaces I managed to build a non-leaking microfluidical chip fullling all the requirements. Unfortunately, the examination of the completed microfluidical structure was not possible,therefore, I needed to construct the microfluidical system in PDMS-glass structure also.

Several experiments were designed for measuring the effectivity and characteristics of the separation. According to our results, the designed micruuidical structure fullled the expectations. I conducted experiments also for challenging the functioning of the structure. However, the results were different from the ones mentioned in the literature; I menaged to prove the existence of separation.


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