Dynamically modulated gating process of nanoporous membrane at sub-2-nm speed

Gating properties of nanochannels, as the key nanofluidic behavior, have huge applications in sensing, mass transportation, and separation. The terminal "open" and "closed" states in response to changes in environments have been widely studied. Yet to date, control of the dynamic gating process at quantitatively nanoscale speed remains a great challenge. Here, we modulate the dynamically electric gating process in a polypyrrole (PPy)-based nanoporous membrane system at sub-2-nm speed. The nanoconfinement environment endows the polymer chain with excellent electrochemical properties, and the polymer film swells or contracts at a controlled speed, accompanied by a reversible counterion uptake or expulsion. With this switching process, the thickness of the polymer changes by 83%, resulting in a fully closed gating state. In addition to atomic force microscope (AFM) topography in situ, the small operation voltages and ultra-high-strain scope, along with biocompatible materials, make this design promising for smart nanorobot and wearable electronics.