Frequency domain response of memristors, synapses and neurons - YouTube
A memristor is a two-terminal device that undergoes a voltage-controlled conductance change. Because the resistance depends on the history of the system, it has a strong hysteresis effect and produces a resistance switching. Memristors are the key elements for neuronal networks, as the memory effect represents plasticity of synapses. Neurons have the same ingredients as memristors plus at least one negative resistance that destabilizes the system in a Hopf bifurcation that passes the dynamics from rest to a spiking state. The operation of spiking networks occurs by transference and integration of electrical impulses, but the characterization of the material elements is much better done in the frequency domain, by the techniques of impedance spectroscopy.1 Here we provide the methods to assess memory, plasticity and spiking in the frequency domain, and we show the transformation to the time domain. We present the fundamental model of a halide perovskite memristor, that describes the behaviour both in time and frequency domain.2 Next, we show the impedance spectroscopy criteria for dynamical regimes of a FitzHugh-Nagumo model, that is a representative minimal model of a spiking neuron.3 We expand the analysis to cover the possible impedance spectroscopy behaviours of all two-dimensional oscillating systems. In conclusion we show that impedance spectroscopy is a strong characterization method for producing memristors, synapses and neurons with tailored temporal dynamics, hysteresis, and rhythmic oscillations for neuromorphic computing.
(1) Guerrero, A.; Bisquert, J.; Garcia-Belmonte, G. Impedance spectroscopy of metal halide perovskite solar cells from the perspective of equivalent circuits, Chemical Reviews 2021, 121, 14430–14484.
(2) Bou, A.; Bisquert, J. Impedance spectroscopy dynamics of biological neural elements: from memristors to neurons and synapses, J. Phys. Chem. B 2021, 125 9934–9949.
(3) Bisquert, J. A frequency domain analysis of excitability and bifurcations of Fitzhugh-Nagumo neuron model., J. Phys. Chem. Lett. 2021, 12, 11005–11013.