Ion-specific Activation and Inactivation of Ion Transport in 2D Subnanoporous Membrane

Ion transport at the nanoscale plays a crucial role in numerous biological functions, including neural signaling, muscle contraction, and auditory perception. One phenomenon critical in biology is mechanosensitive ion transport, serving as basis for transducing mechanical inputs (e.g., sounds and touch) into electrical signals. In artificial systems, such transport has been computationally demonstrated in the form of stretch-activated transport in sub-nanoporous 2D membranes. Here, we report an opposite behavior, wherein ion transport is inactivated upon stretching a 2D porous membrane. Using extensive molecular dynamics simulations, we demonstrate a reduction in aqueous K⁺ transport by a factor of 3-8 under ~3% stretching, depending on the material and pore structures. In striking contrast, the same porous membranes exhibit enhanced Na⁺ ion transport under tensile stretching of the same magnitude. This type of ion-specific activation and inactivation induced by membrane stress is, in fact, utilized by biological systems, except in a far more complex fashion. We explain in detail the physical mechanisms underlying the observed mechanosensitive behaviors to further enable biomimetic functionalities in artificial nanofluidic systems.