The past, present, and future of in vivo-implantable recording microelectrodes: the neural interfaces

Abstract

The electrical signals between neurons are crucial in human perception, emotions, and behaviors. Abnormal activities of these signals are associated with sensory organ disorders such as pain, visual and auditory impairments, and neurological disorders including depression, paralysis, and epilepsy. The use of implanted microelectrodes for detecting and intervening in neuronal activity plays a significant role in diagnosing and treating diseases. Notably, as a key component of brain–computer interfaces (BCI), the rapid advancement of BCI technology has expanded the application of implantable recording microelectrodes in treating brain dysfunction. The transition from metal to flexible electrodes has marked significant advancements in materials and properties (biocompatibility, resolution and number of sites, stability, and functional integration, etc.) as well as surface modifications. However, these advancements also present challenges and shortcomings, particularly regarding the biocompatibility and electrochemical properties of electrodes. This paper reviews the development history of electrodes and common types, addressing the biocompatibility and electrochemical performance issues and their advances and future development directions. This discussion aims to serve as a reference for further improvements in electrode performance.