Molecular streaming and its voltage control in ångström-scale channels
Publication Date: 06 March, 2019
Department of: Physics and Astronomy
Transistor-like operation of hydrodynamic nano-channels
Van der Waals assembly of two-dimensional materials allows the creation of artificial channels with ångström-scale precision, opening new ways to fabricate nanometre scale fluidic devices. Earlier studies of researchers at the University of Manchester have shown that, when filled with water, such channels rearrange it into one or two layers of H2O molecules with strongly suppressed dielectric permittivity, or form a room-temperature two-dimensional ice phase. Now, a collaboration between the University of Manchester and Sorbonne Université have found out how water and dissolved ion transport are coupled in such confinement. They have demonstrated a transistor-like electro-hydrodynamic effect: An applied bias of a fraction of a volt can increase the measured pressure-driven ionic transport (characterized by streaming mobilities) by up to 20 times. This gating effect is observed in both graphite and hexagonal boron nitride channels but exhibits marked material-dependent differences. This highly nonlinear gating of fluid transport under molecular-scale confinement may offer new routes to control molecular and ion transport, and to explore electromechanical couplings that may have a role in recently discovered mechanosensitive ionic channels.