Conducting polymers for implantable neural electrodes in brain-computer interfaces

As core elements of brain-computer interfaces, neural electrodes play a vital role in neural signal recording and stimulation. Conventional metallic electrodes, however, suffer from several inherent drawbacks, including mechanical mismatch with soft neural tissues, high interfacial impedance, and chronic inflammatory responses following implantation. In contrast, conducting polymers (CPs) possess unique comprehensive advantages, rendering them ideal candidate materials for advanced neural electrodes. Based on systematic research, key performance criteria are proposed for next-generation neural electrodes, namely mechanical compliance, electrochemical characteristics, long-term stability, biocompatibility, functional integration, and fabrication feasibility. Guided by this performance evaluation framework, we systematically review recent progress in CP-based neural electrodes, with special focus on CP coatings, nanocomposites, hydrogel composites, all-polymer devices, and biofunctionalized interfaces for optimizing electrode performance. Finally, we summarize the present unresolved limitations and outline future research directions for CP-enabled neural interfaces. This review is expected to provide valuable references and systematic guidance for the innovation and development of next-generation multifunctional neurodevices.