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

Serotonin (5-HT) is a major neurotransmitter broadly involved in many aspects of feeling and behavior. Although its electro-active feature renders the electrochemical sensor promising, the persistent generation of fouling layers on 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 to sensing different neurochemicals having significant fouling issues, thus facilitating the molecular-level understanding of brain function.