Bio-Compatible Flexible Memristive Devices Enabled by BNNT/MWCNT-ZnO Quantum Dot Hybrid Percolation Networks

Flexible, transparent resistive random-access memory (ReRAM) is promising for next-generation wearable and bio-integrated electronics requiring low power and material safety. Here, we report a flexible and transparent ReRAM device based on a BNNT rod/MWCNT-ZnO quantum dot (QD) nanocomposite and evaluate its electrical operation under static bending, stability after low-temperature exposure, and biocompatibility. The fabricated Al/nanocomposite/ITO/PET device exhibited approximately 63% optical transmittance in the visible region and maintained resistive switching under a 3 cm static bending radius. It demonstrated nonvolatile memory characteristics, including an ON/OFF current ratio over 10³, electrical endurance exceeding 20 000 cycles, and retention beyond 75 000 s. The memory performance remained stable at -30°C, indicating environmental robustness. Charge transport analysis revealed that switching behavior is governed by space-charge-limited current (SCLC) conduction at low voltages and Fowler-Nordheim tunneling at high electric fields, while the BNNT layer acts as a charge-blocking layer to enhance retention stability. For biocompatibility, cytotoxicity testing showed cell viability satisfied ISO 10993-5, while 8-week subcutaneous implantation revealed a transient acute inflammation that attenuated over time without necrosis. Despite non-encapsulated conditions, explanted devices retained distinguishable resistive states, demonstrating in vivo functional stability. Overall, this nanocomposite-based ReRAM shows potential as a memory platform for wearable and implantable bioelectronics.