Faculté des sciences

Development of microfluidic devices for chemical analysis and fluid handling

Egidi, Giovanni ; De Rooij, Nicolas F (Dir.)

Thèse de doctorat : Université de Neuchâtel : 2004 ; 1743.

Miniaturization of chemical analysis and synthesis systems improve throughput, performance and accessibility, and lead to significantly reduced costs. In this work are described several components that find place in the process of miniaturization. This work is developed in the frame of the project CREAM (Cartridges with molecularly imprinted Recognition Elements for Antibiotic residues Monitoring... Plus

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    Summary
    Miniaturization of chemical analysis and synthesis systems improve throughput, performance and accessibility, and lead to significantly reduced costs. In this work are described several components that find place in the process of miniaturization. This work is developed in the frame of the project CREAM (Cartridges with molecularly imprinted Recognition Elements for Antibiotic residues Monitoring in Milk). Antibiotics are widely used to treat cows' diseases, and traces can be found in milk some days after treatment. The presence of antibiotics in milk represents a potential human health hazard, and can present problems for cheese and yoghourt makers. The aim of this work is to produce a device able to detect the presence of antibiotics in milk. This device should be the most compact as possible, and have to reduce the cost of the analysis. A plastic replication technique by cast molding is developed in order to quickly produce plastic prototypes starting from a master made in silicon and photoresist (SU-8). By exploiting capillary effect, is developed a stop flow valve. The valve is integrated in a microfluidic device realized by DRIE (Deep Reactive Ion Etching) on a silicon wafer. It consists in a vertical capillary connecting the channel on top of the wafer, to the expansion chamber etched on the back-side. The device is finally closed by anodic bonding with two pyrex lid. Passive stop flow valves are used to realize a sample metering system. Such a system consists in an introduction port for the sample, a capillary and two valves, one of which acts as air vent. Furthermore a micro drier is developed using the functioning principle of the stop flow valve. The application of this device it to change the liquid phase of a solution, in particular in the project CREAM in necessary to change an aqueous solution into an almost pure solution of acetonitrile. A new optical detection cell design is fabricated. It consists on an array of channels open at the end, the meniscus formed at the outlet of each channel provides a direct air-liquid interface to the sample volume, through which light could be injected. This optical detection cell is integrated in a cartridge with a microreactor and a sample metering system. The microreactor is packed with MIPs (Molecular Imprinted Polymers) and characterized from the fluidic point of view. The whole cartridge is finally optically characterized with pyrene butyric acid