S. Karakitsiou, S.D. Eder, B. Holst, A.C. Hoffmann
University of Bergen, Norway
pp. 214 - 217
Keywords: nanofluidic devices, slip flow, Knudsen flow, diffusion
In this work an apparatus, designed to measure gas diffusion through nanochannels, is introduced. All calculations for the construction have been made for 2000 nanochannels with a diameter of 100 nm and a length of 2 μm. This setup is based on a pressure difference-driven transport and the selection of the initial and final pressures has been made so that the transport follows the Knudsen diffusion model through the whole channel length. It is shown how the apparatus is designed and tested for flow in the Maxwell slip regime through a 0.35 mm diameter channel. Comparisons between theory and experiments are made. The advantage of the proposed apparatus is that it makes it possible to measure a wide range of flow profiles due to the fact that the pressures can be adapted to create different flow regimes. The characteristic dimensions of the system of course are critical. Thus, the structures have to be constructed with accurate methods in the nanoscale such as electron beam lithography. Today, nanoscale geometries such as porous membranes, carbon nanotubes and mesoporous silica are applied in microelectromechanical systems (MEMS). Thus, knowledge of gas diffusion through them makes it possible to address fundamental challenges.