  Bio-integrated neuromorphic systems promise for new protocols to record and
regulate the signaling of biological systems. Making such artificial neural
circuits successful requires minimal circuit complexity and ion-based operating
mechanisms similar to that of biology. However, simple leaky integrate-and-fire
model neurons, commonly realized in either silicon or organic semiconductor
neuromorphic systems, can emulate only a few neural features. More functional
neuron models, based on traditional complex Si-based
complementary-metal-oxide-semiconductor (CMOS) or negative differential
resistance (NDR) device circuits, are complicated to fabricate, not
biocompatible, and lack ion- and chemical-based modulation features. Here we
report a biorealistic conductance-based organic electrochemical neuron (c-OECN)
using a mixed ion-electron conducting ladder-type polymer with reliable
ion-tunable antiambipolarity. The latter is used to emulate the
activation/inactivation of Na channels and delayed activation of K channels of
biological neurons. These c-OECNs can then spike at bioplausible frequencies
nearing 100 Hz, emulate most critical biological neural features, demonstrate
stochastic spiking, and enable neurotransmitter and Ca2+-based spiking
modulation. These combined features are impossible to achieve using previous
technologies.
