Membrane separation processes are efficient and sustainable alternatives to energy intensive distillation operations. In gas separations, polymeric membranes dominate the landscape of industrial applications and many improvements in performance hinge on the ability to tailor the chemistry of polymeric materials. The basic goal in membrane separations is to control the solubility and diffusivity of the chemical compounds in order to tailor the relative magnitude of the fluxes of the chemical species across the membrane. In this paper, we introduce a fundamentally new separation device that uses an anisotropic polymeric membrane to guide molecular transport to specific spatial locations. Our proposed separation device enables to manipulate the flux direction of compounds, in addition to the flux magnitude, thus adding a new tool to separate chemical species. We report unprecedented selectivities for O-2/N-2 separation - up to two orders of magnitude larger than conventional membranes.