Ciencias Exactas y Ciencias de la Salud

Sepsis is the main cause of neonate death in hospitals. According to WHO, around one million neonatal deaths are caused each year because of sepsis. Rapid and early sepsis detection, are necessary for effective treatment of the patients to reduce the mortality rate, however this is still a big challenge, especially in low income countries with a poor healthcare system. Recently, soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) biomarker has showed to be an accurate indicator for sepsis detection in neonates. When compared to conventional tests that take several days up to a week, sTREM-1 immunoassay is a faster approach for sepsis detection as it can be performed in five hours. However, the sTREM-1 immunoassay must be performed in a clinic laboratory by specialized staff and require several expensive and bulky equipment. One way to enable the sTREM-1 immunoassay outside specialized labs or at point-of-care (POC) is the integration of the complex assay into a centrifugal microfluidic platform. The disc-shaped microfluidic platform also known as lab-on-disc (LoD), employs centrifugal force from spinning of the disc to manipulate samples and reagents. The centrifugal force that exist everywhere on the disc prevents the need for several expensive syringe pumps. However, it makes simultaneous control over the retention and flow of several reagents/samples on a LoD challenging. To overcome this problem and automate sTREM-1 immunoassay for POC settings, this document presents the development of a new sacrificial polyethylene and a novel reversible valving mechanism on LoD. Based on the two valving mechanisms, a sTREM-1 immunoassay LoD is developed for sepsis detection. Integrating a series of sacrificial valves in the disc allowed for storage of reagents in the disc and their controlled release to a reaction chamber. The reversible valve, was used for the retention of each reagent in the detection chamber during incubation periods, and then transferring it to a waste chamber. A portable spinning system was developed to run the assay by microfluidic disc at POC. The successful automation of sTREM1 immunoassay on the microfluidic disc can provide a significant contribution in the reduction of complexity of the resources needed for sepsis detection at POC settings, particularly in remote areas.

In this thesis we present a method to determine the thickness of dielectric thin films (<100 nm). The thickness of four magnesium-fluoride (MgF2) thin films of different thicknesses is accurately determined by detecting the angle at which surface plasmon resonance (SPR) occurs. The experiment consists of the measurement of the attenuated total internal reflection using an optical setup based on the Kretschmann configuration. Curves from a theoretical model for multilayer thin film resonance are used to fit the experimental results in order to obtain the dielectric film thickness. Additionally, we calculated numerically the dispersion relation for an insulator-insulator-metal-insulator (IIMI) structure and determined the experimental range of parameters where the system is the most sensitive.

Ciencias Exactas y Ciencias de la Salud

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