Multifunctional and flexible sensing probe for neurotransmitters monitoring and balance modulation

Maintaining a dynamic balance of neurotransmitters such as dopamine and serotonin is fundamental to normal brain function. Real-time monitoring combined with localized chemical delivery may provide a useful strategy for decoding dysregulated neurochemical signaling and supporting future intervention studies in Parkinson's disease, depression, and related neurodegenerative conditions. Here we present a flexible sensing probe that combines high-surface-area rGO/PEDOT:PSS nanocomposite electrodes for fast electrochemical detection with a coplanar microfluidic channel for controlled localized delivery. The device simultaneously quantifies dopamine and serotonin over 0.1-100 μM and hydrogen peroxide over 0.1-1000 μM, achieving sensitivities of 1.89, 2.05, and 328.36 μA μM^-1 cm^-2, respectively, while exhibiting minimal interference from physiologically relevant analytes such as GABA and uric acid. Fluidic characterization demonstrated on-demand drug pulses on the order of seconds at flow rates ≥0.2 mL h^-1, with negligible variation in flow under bending angles ≤30°. Electrochemical tests likewise confirmed stable sensing performance at a bending angle of 30°, consistent with the mechanical robustness required for chronic implantation. By integrating real-time neurochemical monitoring with localized microfluidic delivery in a compact flexible system, this platform provides an engineering basis for future closed-loop neurochemical studies, while direct biological regulation of neurotransmitter balance through local drug injection will require further in vivo validation.