Recent advances in neural electrode-tissue interfaces

Neurotechnology is facing an exponential growth in the recent decades. Neural electrode-tissue interface research has been well recognized as an instrumental component of neurotechnology development. While satisfactory performance was demonstrated in some applications, such as cochlear implants and deep brain stimulators, more advanced devices requiring higher resolution for recording or microstimulation still face significant challenges in reliability and longevity. We review the most recent findings that shed light on the sources of poor reliability and longevity in neural electrodes, including the material failure, biological tissue response and the interplay between the two. We introduce newly developed characterization tools from electrophysiology models, molecular and biochemical analysis, material characterization to live imaging. Effective strategies for improving the interface are also highlighted. Finally, we discuss the challenges and opportunities in improving the interface and achieving seamless integration between the implanted electrodes and neural tissue both anatomically and functionally.