A density functional theory study of tyrosine-proton mediated transport in Ag-filamentary nanodevices

The development of electronic circuits designed to emulate the functionality of biological neural networks has increased significantly in recent years. Specifically, memristor-based neuromorphic operation has been demonstrated using various material combinations. One class of devices replicates the ion-concentration-gradient buildup that precedes neurotransmitter release in biological synapses. Some of these devices incorporate amino-acid-rich solutions as an active layer. This work presents a density functional theory study of such a device. The interaction between an Ag-filamentary memristor and different Hydrogen concentrations in a tyrosine-rich environment was evaluated. Two mutually exclusive structures were studied, and the resulting source-to-drain currents were compared with experimental observations. One structure was based on Tyrosine-H blocks linked to Ag atoms as a charge conduction path, while the other placed these blocks in parallel with Ag partial filaments between the source and drain. The results indicate that the second aligns with experiments and supports the hypothesis that tyrosine can act as an enabler for proton-mediated charge transport. Furthermore, the insights into the electronic transport properties of specific molecules can provide a theoretical background for designing advanced Hydrogen sensors and amino acid detectors.