Ion-Specific and Reconfigurable Nanofluidic Memristor Based on Asymmetrically Nanoconfined Hydrogel

Recent advancements in nanofluidic memristors have drawn significant attention owing to their capability to mimic neuromorphic functions observed in biological neural systems. However, challenges remain in structure miniaturization and achieving ion-specific and complex neuromorphic functions. Hydrogels, with excellent ionic conductivity and dynamic porous structures, establish an ideal ionic transport environment. Moreover, their diverse chemical functionalities enable pH- or electric field-modulated ion selectivity. Here, a miniaturized on-chip nanofluidic memristor based on asymmetrically nanoconfined polyacrylic acid (PAA) hydrogel is reported. The device exhibits distinct transport behaviors depending on ion species, attributed to different interaction strengths between cations and carboxyl groups. Through diverse electrical modulations, neuromorphic functionalities including short-term plasticity, long-term plasticity, and spike-timing-dependent plasticity are demonstrated. Beyond electrical modulation, the device can also be chemically modulated. By regulating the pH of the solution and hence modulating the cation–hydrogel interactions in the nanofluidic channel, the device can achieve reconfigurable synaptic functions. Furthermore, by integrating two devices into series and parallel circuits, the “synaptic integration” function of biological neurons is mimicked, enabling fundamental “AND” and “OR” logic operations. This work presents a nanofluidic platform achieving ion-specificity, electrical control, chemical reconfiguration, and biomimetic integration, laying the groundwork for complex brain-like computing.