Ion-Doped Nanofluidic Memristors: A Platform for Tunable Synaptic Emulation

Nanofluidic ionic memristors have garnered considerable attention for their operational principles that emulate biological synapses, positioning them as promising candidates for neuromorphic systems. However, simultaneously achieving non-volatility and function-tunability in ionic memristors remains a significant challenge. Here, we demonstrate the successful emulation of key neuromorphic functions, including neural activation and synaptic plasticity, using a nanofluidic memristor integrated with sub-nanometer (sub-nm) channels within ion-track membranes. Unlike unipolar resistive switching, which is predominantly driven by concentration polarization in symmetric ion solution system, we demonstrate a reversible transport switching mechanism, triggered by multivalent ions (e.g., Ca²⁺ and La³⁺), that toggles between fast and slow modes. This mechanism induces a transition to bipolar resistive switching, significantly enhancing the device's non-volatility while preserving its reversibility. Furthermore, the memristive response can be effectively tuned by varying the doping concentration and external voltage. These findings provide new insights and design strategies for developing tunable bio-synapse emulation platforms operating in ionic aqueous media.