Memristor-Like Behavior in Asymmetric Nanopores Induced by Nanoprecipitation

Nanopores provide controlled nanoconfinement that could be utilized to induce localized chemical reactions. Here we present a nanopore exhibiting memristor-like features, where the memory effects stem from the reaction of nanoprecipitation induced within the pore volume. When exposed to solutions of weakly soluble cobalt ion salts, single conical nanopores in polymer films exhibit transient current blockades observed as oscillations in the transmembrane current. These oscillations are modeled as switching between two conductivity states. We find that the onset and characteristics of these current instabilities depend on the direction of the voltage scan, with consistent memory in the likelihood the pore is in the high or low conductivity state. These sustained current oscillations are reminiscent of neurons, whose behaviors are dependent on the frequency and amplitude of past signals. We have also emulated conductive synaptic switching behavior by applying pulsed voltages, demonstrating the prospect of these nanopores for neuromorphic computing applications. We hypothesize that the memory effects arise from the formation and delayed clearing of nanoprecipitates due to a diffusion-based spatial-temporal asymmetry, as well as long term variations in the surface charge distribution. Nanoprecipitation-based memristors could be used to create a model system for neuromorphic computing.