Molecular Layer Deposition of Biomimetic Amino Acid-based Hybrid Thin Films for Artificial Nociceptors

Abstract

With the rapid development of artificial intelligence, the need to mimic biological functions have become increasingly important for completing complex tasks and adapting to challenging external environments. Memristors, recognized for their biological-like capabilities, have emerged as a promising candidate for neuromorphic artificial electronic devices, sparking significant research interest. In this study, we drew inspiration from neurotransmitters in the human brain and selected essential amino acids as organic components to construct biomimetic hybrid films. Using cysteine (Cys) as the organic precursor, titanium-based cysteine hybrid thin films were successfully synthesized via molecular layer deposition (MLD). In situ quartz crystal microbalance measurements confirmed that the MLD process of Ti-Cys followed a self-limiting surface reaction with a growth rate of approximately 0.29 Å per cycle at 135 ℃. The stability of the hybrid films was extensively examined, demonstrating excellent durability in both water and air. The potential of these biomimetic hybrid films as resistive functional layers was also explored. A vertically integrated Pt/Ti-Cys/TiN device exhibited reproducible volatile switching behavior, with gradual changes observed during the set/reset process. The resistive switching mechanism of this Ti-Cys hybrid-based devices is mainly governed by charge trapping and de-trapping processes. The volatility of the hybrid memristor devices originate from the trapped electron relaxation/diffusion from shallow traps after removal of the external bias. Notably, the device successfully emulated bio-pain sensation and synapse functions, indicating that these biomimetic hybrid films hold great potential for the development of artificial sensory systems.