Fig. 1. (Color online) (a) 1T1R structure based on volatile diffusive memristors. The transistor is placed in series to obtain better control of the maximum flowing current. (b) Schematic diagram of the arrangement of the silver atoms inside hafnium oxide with switching between LRS and HRS. (c) Schematic diagram of the arrangement of parallel cells based on the 1T1R cell. (d) Examples of filtered temporal current traces collected in the experiment with different frequency. (e) Histograms showing the normalization of ON device counts across various frequencies reveal a shift in the peak towards the right with frequency increase, indicating a rise in the quantity of active devices. (f) Linear mapping of log-spaced frequencies in our systems and in the cochlea. Reprinted from Ref. [26], with permission of Nature.

Fig. 2. (Color online) (a) Multiple types of spiking behavior such as sustained spiking, bursting, phasic spiking, and mixed-mode spiking realized by VO₂-based Mott memristors. (b) VO₂-based Mott memristors for artificial neurons resembling the structure of the cerebral cortex. Reprinted from Ref. [29], with permission of Nature.

Fig. 3. (Color online) (a) Schematic of the work-cognition tasks realized by reservoir computing systems based on optoelectronic memristive neurons. (b) Schematic of an optoelectronic memristive neuron stimulated by hybrid electrical and optical inputs. Reprinted from Ref. [9], with permission of Science.

Fig. 4. (Color online) (a) Diagram of the structure of the 1TFT1R volatile memristor serves as a time-surface neuron with temporal kernel function. (b) Sample image of the packaged 32 × 36 1T1R memristor array (1 kb) with the TiN/TaO_x/HfO₂/TiN structure wire boned in a chip holder. (c) PCB subsystem hardware for the audio recognition consists of the 1TFT volatile memristors, 1T1R memristors array, analog circuits, and communication interface. Reprinted from Ref. [69], with permission of Science.

Fig. 5. (Color online) Future directions of memristor-based artificial neurons for neuromorphic applications and strategies to address challenges.