Galvanic Redox Potentiometry for Fouling‐Free and Stable Serotonin Sensing in a Living Animal Brain

Abstract Serotonin (5‐HT) is a major neurotransmitter broadly involved in many aspects of feeling and behavior. Although its electro‐activity makes it a promising candidate for electrochemical sensing, the persistent generation of fouling layers on the electrode by its oxidation products presents a hurdle for reliable sensing. Here, we present a fouling‐free 5‐HT sensor based on galvanic redox potentiometry. The sensor efficiently minimizes electrode fouling as revealed by in situ Raman spectroscopy, ensuring a less than 3 % signal change in a 2 hour continuous experiment, whereas amperometric sensors losing 90 % within 30 min. Most importantly, the sensor is highly amenable for in vivo studies, permitting real‐time 5‐HT monitoring, and supporting the mechanism associated with serotonin release in brain. Our system offers an effective way for sensing different neurochemicals having significant fouling issues, thus facilitating the molecular‐level understanding of brain function.