Highly\nSelective and Excitable Artificial Ion Channel\nfor Spike Generation

Cation channels of the neuron can\nbe excited by neurotransmitters\nand have high ionic selectivity, which are crucial for the generation\nof spikes. Intuitively, if a channel has both a high ionic selectivity\nand excitability, it may be used to generate spikes. However, integrating\nthe high selectivity and excitability in a single channel remains\nhighly challenging. In this work, we demonstrate an artificial ion\nchannel based on a wetting film between an oil droplet and a glass\nsubstrate. The channel height is dominated by the repulsive electrostatic\ninteraction between the glass/water and water/oil interfaces and is\ntherefore highly adaptable to ambient ions and charged surfactant,\nsetting the basis for flexible control of the open/close state and\nion selectivity. The channel stays in a closed state unless excited\nby an anionic surfactant. Once excited, the channel opens wide for\nmonovalent ions but narrows for divalent ions, exhibiting a selectivity\nup to >6800. By exploiting such excitability and selectivity, we\nconstructed\na prototype artificial neuron for spike generation. Using the anionic\nsurfactant to simulate the neurotransmitter, our artificial neuron\ncan automatically and step-wisely open and close the channel, generating\na current spike with adjustable magnitude. We expect our work to inspire\nthe development of biomimetic devices for potential neuromorphic computing\napplications.