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Abstract

An organic artificial neuron that is based on a compact nonlinear electrochemical element can operate in a liquid and responds to the concentration of biological species in its surroundings, allowing its behaviour to be modulated, for example, by interfacing with the membranes of living cells. The effective mimicry of neurons is key to the development of neuromorphic electronics. However, artificial neurons are not typically capable of operating in biological environments, which limits their ability to interface with biological components and to offer realistic neuronal emulation. Organic artificial neurons based on conventional circuit oscillators have been created, but they require many elements for their implementation. Here we report an organic artificial neuron that is based on a compact nonlinear electrochemical element. The artificial neuron can operate in a liquid and is sensitive to the concentration of biological species (such as dopamine or ions) in its surroundings. The system offers in situ operation and spiking behaviour in biologically relevant environments-including typical physiological and pathological concentration ranges (5-150 mM)-and with ion specificity. Small-amplitude (1-150 mV) electrochemical oscillations and noise in the electrolytic medium shape the neuronal dynamics, whereas changes in ionic (>= 2% over the physiological baseline) and biomolecular (>= 0.1 mM dopamine) concentrations modulate the neuronal excitability. We also create biohybrid interfaces in which an artificial neuron functions synergistically and in real time with epithelial cell biological membranes.