Bioelectronics have been increasing in prevalence, driving extensive studies to develop systems that can perform electronic operations on various organs. In particular, neural recording technologies have undergone rapid development through the integration of advanced materials and electronic systems designed to interface directly with biological environments. Despite the developments of 1D and 2D neural interfaces, their applicability is limited by factors including elevated impedance, mechanical fragility, and poor conformability to inhomogeneous biological surfaces. To overcome these limitations, 3D neural electrodes have been extensively developed. Not only can 3D bioelectrodes enable stable interfacing with the biological surfaces, but also explore deep regions previously inaccessible with surface-based approaches. This review summarizes recent advances in 3D neural electrode architectures, highlighting their key functionalities, underlying materials and structural designs, representative applications, and current challenges.
