Flexible Surface Electrodes for Electrocorticography in Neurological Diseases and Brain‐Computer Interface Applications

Flexible electrocorticography (ECoG) surface electrode arrays have broadened their application scope from clinical neural recording tools to integral components of brain-computer interface (BCI) systems. Currently used ECoG arrays are typically fabricated with metal contacts embedded in silicone carriers, offering limited mechanical flexibility. This restricts their ability to achieve optimal conformal contact with the brain cortex. Moreover, their channel count is constrained by bulky and cumbersome cabling systems. The recent integration of flexible nanomaterials and advanced patterning techniques into surface electrodes has enabled the development of ultrathin, high-density arrays that conform intimately to the cortical surface. These arrays incorporate on-site amplification and multiplexing capabilities while maintaining stable impedance over extended implantation periods. This review article highlights recent technological advancements in ECoG surface electrode arrays, as well as emerging strategies for their application in the diagnosis and treatment of neurological disorders. In addition, it presents current efforts to incorporate surface electrodes into BCI systems through the utilization of neural signals.