Two-Dimensional SnS2 Interlayers Enable Vacancy-Guided Ion Migration for Stable Diffusive Memristors and Bioinspired Nociception.

The realization of sophisticated autonomous interaction in humanoid robots is currently constrained by the complexity and stochasticity of conventional sensory hardware. Volatile memristors provide a promising biomimetic alternative; however, their performance is often limited by uncontrolled ionic dynamics in disordered oxides. Here, we report two-dimensional SnS2 interlayers as an effective platform for vacancy-guided ion migration in oxide-based diffusive memristors. A solution-processed SnS2 layer with tunable sulfur vacancy density is introduced into an Ag/TaOx/SnS2/ITO heterostructure to regulate filament formation. Under electrical bias, sulfur vacancies of SnS2 layer locally enhance the electric field and provide deterministic pathways for Ag+ migration. This enables atomic-scale confinement of conductive filaments, resulting in highly uniform threshold switching (variability ≈ 10.9%), ultralow switching energy (∼ 10.9 pJ), and stable operation over 5,000 cycles. Furthermore, modulation of the vacancy landscape allows dynamic reconfiguration of switching polarity, enabling a transition from unidirectional to bidirectional volatile switching. Beyond improved electrical performance, the devices reproduce key nociceptive behaviors and can be integrated into an 8 × 8 crossbar array to achieve spatially resolved perception of mechanical stimuli.