Apparatus for measuring pressure-driven transport through channels at high Knudsen numbers

The pressure-driven gasflow through micro- and nano-porousstructures is particularly interesting for innovativetechnologies such asmicroelectromechanical and nano-mechanical-electricalsystems. The classical continuum assumption breaks down for rarefiedflow through channels with a characteristic dimension comparable to the mean free path of the gas.Theories based on molecular interactions have been formulated to predict theflow at high Knudsen numbers.Measuring rarefied gasflow experimentally is a challenge since only a few studies have been able to determine flowrates in the molecularflow regime. Here we present the design of an experimental apparatus, which can be used tomeasure theflow of gases through nano- and microscale channels in theflow regimes where molecular effects are critical. Theequations used to design the apparatus are given, focusing on the slip and transitionflow regimes (together sometimes called “Intermediateflow regime ”). A channel with a diameter of 325μm ± 5μm and a length of 2 mm was tested experimentally with the apparatus for a wide range of Knudsen numbers (10−2
Source: Review of Scientific Instruments - Category: Physics Authors: Source Type: research