Thermally stable silk fibroin/carbon nanotube biomemristors for BCM learning rule simulation and neuromorphic computing applications

Silk fibroin (SF) has attracted considerable attention in neuromorphic computing and flexible electronics owing to its outstanding biocompatibility. However, its inherently low thermal stability greatly limits its use in high-temperature and complex environments. In this work, we employed a dual-treatment strategy combining freeze-drying and chemical crosslinking to fabricate silk fibroin/carbon nanotube (SF/CNT) composite films, which markedly enhanced the thermal stability of SF. Thermogravimetric analysis (TGA) revealed that the initial decomposition temperature of the composite film increased by ~65 °C compared to that of pure SF, indicating that the synergistic interaction between CNTs and SF effectively suppresses thermal degradation. More importantly, the SF/CNT film based memristor exhibits synapse-like plasticity and successfully emulates the Bienenstock-Cooper-Munro (BCM) learning rule. By regulating its electrical response under pulse stimulation, the device demonstrates synaptic weight updates dependent on pre and postsynaptic activities, reproducing the threshold sliding mechanism of the BCM rule via the intrinsic memory effect of the material. Furthermore, in a simple neuromorphic network model, the SF/CNT-based memristor achieves rate-dependent directional selectivity, highlighting its potential for spatiotemporal information processing. Overall, this study provides a new strategy for developing bio-based materials with integrated thermal stability and neuromorphic functionality, paving the way for their application in flexible, wearable, and implantable neuromorphic systems.