Flexible Semiconductor Electrode for in Vivo Neurochemical Recording in the Brain

Abstract Neural electrophysiological and neurochemical signals are crucial for understanding brain function and pathophysiology. Advances in neural interface technology have facilitated the capture of these signals via implantable microelectrodes. However, significant challenges persist in developing biocompatible interfaces, particularly in minimizing implantation‐induced tissue damage and preventing biofouling. Conventional noble metal electrodes, while widely used, have limitations in recording neurochemical dynamics and can cause tissue damage due to their rigid nature. Flexible semiconductor electrodes offer a promising alternative, due to their unique photoresponse and biocompatibility, but their photoelectric conversion efficiency is still insufficient, and fabrication methods are limited. This study introduces a novel flexible semiconductor fiber electrode fabricated via wet‐spinning, incorporating an n‐type ternary heterojunction (CdS/CdIn 2 S 4 /ZnIn 2 S 4 ) to enhance photoelectric conversion efficiency. This electrode demonstrated uniform texture, reproducibility, and stability, with superior biocompatibility. Leveraging its photoresponsive properties, a neurochemical recording electrode is developed for real‐time monitoring of hydrogen sulfide levels in epileptic mice brains. This work provides a versatile platform for neurochemical signal acquisition and disease monitoring, offering significant potential for fundamental neuroscience research.