Giant and Programmable Ionic Rectification Induced by Voltage-Driven Dynamic Modulation of Interfacial Electric Double Layer for Bioinspired Neuromorphic Signal Conduction.

Constructing artificial ionic diodes that mimic biological ion channels by suppressing ion diffusion in one direction is crucial for advancing the human-computer interaction. However, existing artificial channels exhibit large leakage current due to their inability to effectively block the channel in the closed state, making it challenging to achieve efficient unidirectional ion transport. In this work, we construct a unipolar ionic diode that regulates unidirectional proton transport by dynamically modulating the formation of an asymmetric electric double layer at the insulator-hydrogel interface in response to applied voltage. The construction of hierarchical hydrogel nanochannels with light-responsive spiropyran derivatives substantially boosts proton transport kinetics, enabling a record-high rectification ratio of 4 × 105. With this diode, a photonic synaptic transistor with excellent current modulation capabilities, optical synaptic plasticity, and potential for wireless communication is successfully constructed. The exceptional capability of voltage-dependent ion-to-electron signal transduction paves the way for advancing bioinspired nanofluidic ionotronics toward future neuromorphic devices.