A Wireless Optoelectronic Probe Monitors Tissue Oxygenation in the Deep Brain

ABSTRACT Real-time detection of tissue oxygenation in the nervous system is crucial for neuroscience exploration and clinical diagnostics. Compared to blood oxygenation, the partial pressure of oxygen in brain tissue (PbtO 2 ) possesses more direct relevance to local neural activities and metabolic conditions. In this paper, we present an implantable optoelectronic probe that wirelessly and continuously monitors PbtO 2 signals in the deep brain of living animals. The thin-film, microscale implant integrates a light-emitting diode and a photodetector coated with oxygen sensitive dyes. Powered by a battery or an inductive coil, a miniaturized circuit is capable of recording and wirelessly transmitting PbtO 2 signals, which allows for simultaneous monitoring of PbtO 2 levels in multiple freely moving rodents. The wireless micro-probe captures cerebral hypoxia states of mice in various scenarios, including altered inspired oxygen concentration, acute ischemia. Particularly, in mouse models with seizures, the micro-probe associates temporal PbtO 2 variations in multiple brain regions with electrical stimulations imposed in the hippocampus. These materials and device strategies overcome the limits of existing oxygen sensing approaches and provide important insights into neurometabolic coupling.