Exploration of the proton conduction behavior in natural neutral polysaccharides for biodegradable organic synaptic transistors

Abstract

Natural biomaterials have recently attracted growing interest in the construction of artificial synaptic transistors, since as-fabricated electronic devices are typically sustainable, biodegradable, biocompatible, and metabolizable. Most importantly, proton conduction has been discovered in a variety of polyelectrolyte-type natural biomaterials, and the protons mainly originate from the ionizable groups of such materials themselves. However, the previous theory is not applicable to neutral natural biomaterials, whose groups in their molecular chains can hardly dissociate ions. Here, we construct a biodegradable organic synaptic transistor based on neutral-polysaccharide dielectric, and explore the influence of water content and hydroxyl content on the proton conduction behavior. Our results suggest that protons originate from the self-dissociation of water, and then migrate along a continuous hydrogen-bond network under the electric field. Furthermore, natural polysaccharides, with the unique traits of biodegradability, biocompatibility and solubility, allow the preparation of biodegradable and ultraflexible organic synaptic transistors. Therefore, our devices can conformally adhere to various uneven surfaces and degrade in water harmlessly after their programmed lifetime. This study paves a new way to develop “green” and soft artificial nervous systems, providing a meaningful guidance for synaptic transistors based on neutral polymers and expanding the possibility of applying neutral biomaterials to neuromorphic systems.