“…37 RRAM with bipolar switching behavior can exhibit multilevel conductance by controlling the limiting current (I CC ) of the device, which provides the possibility for the preparation of artificial synapses to simulate biological synaptic plasticity and the construction of biomimetic neuromorphic systems. [38][39][40][41][42] To date, various materials, including metal oxides, 43,44 metal nitrides, 45 and organic matter, 46 have shown synaptic behaviour. Compared with other materials, biological materials have the advantages of being convenient to obtain, simple to process, nontoxic, harmless, biocompatible and degradable.…”