  Fine-tuned ion transport across nanoscale pores is key to many biological
processes such as neurotransmission. Recent advances have enabled the
confinement of water and ions to two dimensions, unveiling transport properties
unreachable at larger scales and triggering hopes to reproduce the ionic
machinery of biological systems. Here we report experiments demonstrating the
emergence of memory in the transport of aqueous electrolytes across
(sub)nanoscale channels. We unveiled two types of nanofluidic memristors,
depending on channel material and confinement, with memory from minutes to
hours. We explained how large timescales could emerge from interfacial
processes like ionic self-assembly or surface adsorption. Such behavior allowed
us to implement Hebbian learning with nanofluidic systems. This result lays the
ground for biomimetic computations on aqueous electrolytic chips.
