Unveiling the analogies between the atomic switch and NMDA receptor-based signal transmission of biological synapse

For the successful implication of brain-inspired computing using neuromorphic hardware, it is important to understand the detailed mechanisms of the biological brain. Here, we compare the atomic switch device with the N-methyl-D-aspartate receptor-based (NMDAR) signaling pathway which is the key to cognition in the human brain. An Ag/Ag2S/Pt gapless-type atomic switch configuration is realized using an atomic force microscope. The current responses to single and multiple voltage pulses of varied amplitude, width, and interval are studied to identify and control the conductance levels. This enables us to distinguish the sensory, short-term, and long-term memories along with the passive forgetting behavior and multilevel memory storage properties. Drawing a one-to-one comparison of these aspects of the atomic switch with the learning in the NMDAR pathway, we argue that the atomic switch has the potential not only as an edge-intelligent device but also as the missing link between biology and technology.