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In the developing world, there are large populations suffering from infectious diseases, many of whom are located in remote regions. With the rapid growth in microfluidic systems in recent years, complex functions of conventional diagnostic equipment have been miniaturized and integrated into small devices at the size of a credit card (so-called portable Point-of-care (POC) devices). In this thesis a novel approach to overcoming the challenge of in-field biological sample processing and preparation to produce high quality fluids that can be readily used for downstream testings is described and proof of concept experiments presented. This approach uses hydrodynamic effects and combines nanoporous membrane with microfluidic systems and to filter the cellular component of blood. Experiments presented here demonstrate successful cells filtration from whole blood. Employing hydrodynamic effects is also shown to be an effective and potentially useful technique to isolate cells and plasma within appropriate micro-architectures.

In the developing world, there are large populations suffering from infectious diseases, many of whom are located in remote regions. With the rapid growth in microfluidic systems in recent years, complex functions of conventional diagnostic equipment have been miniaturized and integrated into small devices at the size of a credit card (so-called portable Point-of-care (POC) devices). In this thesis a novel approach to overcoming the challenge of in-field biological sample processing and preparation to produce high quality fluids that can be readily used for downstream testings is described and proof of concept experiments presented. This approach uses hydrodynamic effects and combines nanoporous membrane with microfluidic systems and to filter the cellular component of blood. Experiments presented here demonstrate successful cells filtration from whole blood. Employing hydrodynamic effects is also shown to be an effective and potentially useful technique to isolate cells and plasma within appropriate micro-architectures.

Most patients diagnosed with End Stage Renal Disease (ESRD) undergo hemodialysis. Traditional hemodialysis treatment requires patients spending three to five hours every other day while yielding the high waste level accumulated between treatments. These limitations in the current technology have spurred the development of a portable renal replacement system. The portable system will not only free the patients from visiting the clinic but also allow more frequent treatment that will lead to lower average waste level. To realize a portable system, the size and weight of hemodialysis system components should be reduced. This work analyzes the working principle of the pump and proposes a DC-motor and cam driven finger pump design. In addition, an analytical pump model is created for the optimization of the pump design. In vitro experiment conducted using the pump measured Creatinine levels over time, and the results validitate the design for the portable renal replacement system. The proposed pump design is smaller than 188 cm³ and consumes less than 4W while providing a flow rate of more than 100ml/min (the optimum flow rate for a portable system) for both blood and dialysate flows. The smallest pump of a portable renal replacement system in the literature uses check valves, which considerably increase the overall manufacturing cost and possibility of clogging. Compared to that pump, the proposed pump design achieved reduction in size by 40% and savings in energy consumption by 65% with the removal of valves. This simple and reliable design substantially enables development of a portable renal replacement system.

<p>There is a strong trend in fabricating <i>miniaturized total analytical systems</i>, µTAS, for various biochemical and cell biology applications. These miniaturized systems could e.g. gain better separation performances, be faster, consume less expensive reagents and be used for studies that are difficult to access in the macro world. Disposable µTAS eliminate the risk of carry-over and can be fabricated to a low cost.</p><p>This work focused on the development of µTAS modules with the intentional use for miniaturized diagnostics. Modules for blood separation, desalting, enrichment, separation and ESI-MS detection were successfully fabricated. Surface coatings were additionally developed and evaluated for applications in µTAS with complex biological samples. The first heparin coating could be easily immobilized in a one-step-process, whereas the second heparin coating was aimed to form a hydrophilic surface that was able to draw blood or plasma samples into a microfluidic system by capillary forces. </p><p>The last mentioned heparin surface was further utilized when developing a chip-based sensor for performing CD4-count in human blood, an important marker to determine the stage of an HIV-infection.</p><p>All devices in this work were fabricated in PDMS, an elastomeric polymer with the advantage of rapid and less expensive prototyping of the microfabricated master. It was shown that PDMS could be considered as the material of choice for future commercial µTAS. The devices were intentionally produced using a low grade of fabrication complexity. It was however demonstrated that even with low complexity, it is possible to integrate several functional chip modules into a single microfluidic device.</p>

There is a strong trend in fabricating miniaturized total analytical systems, µTAS, for various biochemical and cell biology applications. These miniaturized systems could e.g. gain better separation performances, be faster, consume less expensive reagents and be used for studies that are difficult to access in the macro world. Disposable µTAS eliminate the risk of carry-over and can be fabricated to a low cost. This work focused on the development of µTAS modules with the intentional use for miniaturized diagnostics. Modules for blood separation, desalting, enrichment, separation and ESI-MS detection were successfully fabricated. Surface coatings were additionally developed and evaluated for applications in µTAS with complex biological samples. The first heparin coating could be easily immobilized in a one-step-process, whereas the second heparin coating was aimed to form a hydrophilic surface that was able to draw blood or plasma samples into a microfluidic system by capillary forces. The last mentioned heparin surface was further utilized when developing a chip-based sensor for performing CD4-count in human blood, an important marker to determine the stage of an HIV-infection. All devices in this work were fabricated in PDMS, an elastomeric polymer with the advantage of rapid and less expensive prototyping of the microfabricated master. It was shown that PDMS could be considered as the material of choice for future commercial µTAS. The devices were intentionally produced using a low grade of fabrication complexity. It was however demonstrated that even with low complexity, it is possible to integrate several functional chip modules into a single microfluidic device.