<p>Electronic devices that mimic biological synapses via ion doping mechanisms have been developed and these devices play a critical role in implementing artificial neural networks into hardware due to their biological relevance and potential for low power consumption and high energy-efficiency. In this review, we discuss operating principles and characteristics of representative ion-doped synaptic devices, such as organic electrochemical transistors (OECTs) and hydrogen doped rare-earth perovskite nickelate devices. Additionally, we explore their potential in the field of neuromorphic computing and sensing platform. The ability to control ionic transport in both organic and inorganic materials could open up many opportunities to advance the field of next-generation neuromorphic applications.</p> Graphical abstract <p>Schematic illustration of biological synaptic signaling(left) and two representative artificial synaptic devices(right) that mimic this function through ion-doping processes.</p>