Iontronics: Aqueous ion-based engineering for bioinspired functionalities and applications

Iontronics is an artificial platform using ions or molecules as signal carriers in an aqueous environment and is inspired by biological systems and their operating principles. Applications of iontronics have been primarily developed to mimic the characteristics of biological systems or to form seamless biointerfaces for communication. This review provides a comprehensive description of such endeavors in iontronics over the recent decades, as well as demonstrations pertaining to biomimetic nonlinear behaviors and ionic chemical delivery devices. The research highlights and applications are discussed based on the types of charge-selective materials used and their underlying principles. As iontronics is still at the early stage of development and diversification, a brief overview of its historical aspects and origin is first provided, followed by theoretical discussions regarding each iontronic material and its related applications. Finally, the review is concluded with some perspectives regarding future developments of iontronics in relation to natural systems in living organisms.