  To overcome the traditional paradigm of filtration, where separation is
essentially performed upon steric sieving principles, we explore the concept of
dynamic osmosis through active membranes. A partially permeable membrane
presents a time-tuneable feature that changes the effective pore interaction
with the solute and thus actively changes permeability with time. In general we
find that slow flickering frequencies effectively decrease the osmotic
pressure, and large flickering frequencies do not change it. In the presence of
an asymmetric membrane, we find a resonant frequency where pumping of solute is
performed and can be analyzed in terms of ratchet transport. We discuss and
highlight the properties of this resonant osmotic transport. Furthermore, we
show that dynamic osmosis allows to pump solute at the nanoscale using less
energy than reverse osmosis. This opens new possibilities to build advanced
filtration devices and design artificial ionic machinery.
