Glassy Carbon Fiber-like Multielectrode Arrays for Neurochemical Sensing and Electrophysiology Recording

Real-time measurement of neurochemical and electrophysiological activities in the living brain is vital for advancing neuroscience and understanding neurological and psychiatric disorders. Carbon fiber microelectrodes (CFEs) have been widely utilized for in vivo electrochemical detection due to their subcellular size, biocompatibility, and desirable electrochemical properties, and arrays of CFEs have demonstrated excellent multi-site chronic sensing of dopamine (DA) and neural activity recording capabilities. However, manual fabrication of CFE arrays lacks reproducibility and batch production capacity. Alternatively, photolithography enables batch fabrication of glassy carbon multielectrode arrays (GC-MEAs) with high resolution and reproducibility, but the insertion of planar flexible MEAs poses challenges. In this study, we present glassy carbon fiber-like (GCF) MEAs fabricated using photolithography. The GCF MEAs feature fiber-like GC electrodes with small cross-section, facilitating self-insertion into brain tissue without additional aids. Batch fabrication of GCF MEAs allows for customizable designs with no or minimal manual intervention. Comparative analysis with CFEs demonstrates improved electrochemical properties of GCF. In vivo experiments in mouse brains confirm the GCF MEAs' ability to measure neurotransmitter concentrations and record neural activities. This novel fabrication approach is promising for multimodal neural activity and neurotransmitter concentration measurements with minimal footprint, offering significant advancements in neural interface technology for neuroscience research and clinical applications.