Auswahl der wissenschaftlichen Literatur zum Thema „Milli-Fluidics“

With the use of a milli-fluidics device, it is possible to manipulate small amounts of fluid in the millimeter range with pinpoint accuracy. The milli-fluidics are currently lacking in studies of the relationship between fluid viscosity, output velocity and output pressure. Thus, this study examines the effects of viscosity on fluid dynamics in the co-axial and tri-axial milli-fluidics. This geometry of the co-axial and tri-axial milli-fluidics consist of single outlet, two inlets and three inlets, respectively. The tri-axial milli-fluidics is 46 mm long and 11.31 mm wide, while, the coaxial milli-fluidic is 64.73 mm long and 9.2 mm wide. The co-axial milli-fluidics constituted of 775 domain elements and 147 boundary elements, while, the tri-axial milli-fluidics mesh constituted of 1518 domain elements and 178 boundary elements. Laminar flow was observed for the flow of the materials through the channels. When the dynamic viscosity approaches 5 mPa.s, the simulation reveals that the flow rate is inversely proportional to the dynamic viscosity for co-axial milli-fluidics. It was difficult to combine fluids with different viscosities with small volume of water in a narrow boundary, thus the parallel flow of material was observed. When using the one outlet channel for the tri-axial milli-fluidics, the assemble pressure at the three inlets was decreased compared with co-axial milli-fluidic. Even when the dynamic velocity of the fluid at outlet 1 increased, its velocity remained consistent. An extruder using tri-axial milli-fluidics can be used if the interfacial tension for intake 1 is higher than for inlet 2 and the dynamic viscosity of fluid 1 is above 2 mPas, according to the volumetric fraction model. The tri-axial milli-fluidic was found to be suitable for producing cladding of material with the balanced pressure from the two side channels.

Notre étude vise à mettre en œuvre, par des moyens peu coûteux, des dispositifs spécifiques pour l'étude des écoulements et des phénomènes de transfert dans les systèmes milli-fluidiques et à optimiser les méthodes de RMN/IRM pour leur caractérisation. Deux applications en milli-fluidique ont été développées. La première porte sur le suivi du régime d'écoulement et la caractérisation d'instabilités hydrodynamiques ayant lieu dans les micro-mélangeurs. La seconde porte sur la visualisation du développement d'un biofilm dans un capillaire de dimensions submillimétriques et la caractérisation de l'hydrodynamique en présence de ce biofilm. Pour chaque application, un dispositif spécifique a été mis en place, comprenant le système milli-fluidique et la bobine radiofréquence (RF) adaptée à la géométrie et aux dimensions du système. Les bobines milli-fluidiques ont été fabriquées par gravure sur des substrats flexibles en cuivre/Kapton®. Avec les paramètres géométriques considérés, les simulations RF ont montré que les milli-coils produisent un champ intense et homogène et les mesures IRM démontrent une augmentation du rapport signal/bruit par rapport à une bobine commerciale MicWB40, ce qui a permis une analyse détaillée des phénomènes milli-fluidiques dans les deux cas d'étude
Our study aims to implement, with a low-cost methodology, specific devices to study flows and transfer phenomena in milli-fluidic systems and to optimize NMR/MRI methods for their characterization.Two milli-fluidic applications have been developed. The first one consists in the study of the flow regime and hydrodynamic instabilities occurring in micromixers. The second one in the study of the growth of a biofilm in a capillary of submillimeter dimensions and the characterization of the hydrodynamics of the flow in presence of this biofilm. For each application, a specific device was set up, including the milli-fluidic system and the radio frequency (RF) coil adapted to the geometry and dimensions of the system. The milli-coils were fabricated by etching on flexible copper/Kapton® substrates. With the considered geometrical parameters, RF simulations have shown that milli-coils produce an intense and homogeneous field and MRI measurements demonstrate an improvement of the signal-to-noise ratio compared to the commercial MicWB40 probe, which allows the detailed analysis of the above mentioned milli-fluidics phenomena