Development of a flexible multifunctional fiber type neural probe for in vivo real-time dopamine monitoring

Abstract

Dopamine is a major neurotransmitter closely related to neurological and psychological disorders. Real-time dopamine monitoring devices with external stimulation are critical to discovering the unveiled role of dopamine transport and the relationship between dopamine and the progress of neural diseases. Fast cyclic voltammetry (FSCV) has been widely used for in vivo real-time neurotransmitter detection due to its high temporal resolution. However, conventional FSCV devices, 7 μm-diameter carbon fiber microelectrode (CFME), lack multifunctionality. Even in the case of a device with multifunctionality added beyond the existing FSCV device, it showed a limitation in that it could not implement long-term usability. Here, we aim to address the discrepancy between the need for a multifunctional neural device for dopamine detection and the challenges of conventional device form using current material and fabrication methods. We developed two types of multifunctional fibers for chronic in vivo neurotransmitter monitoring: (i) carbon fiber embedded multifunctional probe (CFMP) with 200 μm-diameter, and (ii) carbon nanotube sheet wrapped multifunctional probe (CNTSMP) with 280 μmdiameter. The core optical guide part, manufactured via the thermal drawing process (TDP), consisted of polycarbonate (PC)/Poly(methyl methacrylate) (PMMA) transferring optogenetic stimulation. A flexible, multifunctional neural probe for dopamine monitoring based on FSCV was able to monitor dopamine release evoked by optical stimulation in the ventral tegmental area (VTA) in a rodent model. These flexible multifunctional probes are expected to minimize immune response to conduct a long-term multimodal study with neurotransmitter sensing.