Abstract: A gas separation device comprises a gas separation layer, a first gas volume and a second gas volume, the gas separation layer being arranged between the first gas volume and the second gas volume, the gas separation layer having at least one aperture connecting the first gas volume to the second gas volume. The aperture is configured to taper from the first gas volume to the second gas volume and being dimensioned to enrich a component of the second gas volume in the first gas volume, wherein the aperture is configured as an elongated opening in the gas separation layer, the aperture having a minimum opening width of essentially one time to twenty times the mean free path length of the component of the second gas volume, which is to be enriched.