Monolithic multimodal neural probes for sustained stimulation and long-term neural recording.

Long-term implantable neural probes with dual-mode optical stimulation and simultaneous electrical recording are crucial for modulating neural loop activity in vivo. Traditional probes using "add-on" strategies often suffer from mechanical rigidity, compromised electrical performance, and insufficient biocompatibility, limiting their clinical applicability. In this study, we present a method for the direct laser writing of electrode arrays onto the curved surface of optical fibers, integrating them within a biocompatible polymer coating to create monolithic neural probes. The monolithic probes demonstrate high mechanical bending endurance, stable impedance, and improved biocompatibility, resulting in a lower inflammatory response compared to conventional systems. Furthermore, our method facilitates the multilayer integration of multilayer electrodes onto optical fibers, enabling high-density electrical readout channels. This advancement represents substantial progress in neuroengineering, with promising implications for future neural monitoring and modulation applications.