Ultraflexible Neural\nElectrodes Enabled Synchronized\nLong-Term Dopamine Detection and Wideband Chronic Recording Deep in\nBrain

Ultraflexible neural electrodes have shown superior stability\ncompared\nwith rigid electrodes in long-term <i>in vivo</i> recordings,\nowing to their low mechanical mismatch with brain tissue. It is desirable\nto detect neurotransmitters as well as electrophysiological signals\nfor months in brain science. This work proposes a stable electronic\ninterface that can simultaneously detect neural electrical activity\nand dopamine concentration deep in the brain. This ultraflexible electrode\nis modified by a nanocomposite of reduced graphene oxide (rGO) and\npoly(3,4-ethylenedioxythiophene):poly(sodium 4-styrenesulfonate) (rGO/PEDOT:PSS),\nenhancing the electrical stability of the coating and increasing its\nspecific surface area, thereby improving the sensitivity to dopamine\nresponse with 15 pA/μM. This electrode can detect dopamine fluctuations\nand can conduct long-term, stable recordings of local field potentials\n(LFPs), spiking activities, and amplitudes with high spatial and temporal\nresolution across multiple regions, especially in deep brain areas.\nThe electrodes were implanted into the brains of rodent models to\nmonitor the changes in neural and electrochemical signals across different\nbrain regions during the administration of nomifensine. Ten minutes\nafter drug injection, enhanced neuronal firing activity and increased\nLFP power were detected in the motor cortex and deeper cortical layers,\naccompanied by a gradual rise in dopamine levels with 192 ± 29\nnM. The <i>in vivo</i> recording consistently demonstrates\nchronic high-quality neural signal monitoring with electrochemical\nsignal stability for up to 6 weeks. These findings highlight the high\nquality and stability of our electrophysiological/electrochemical\ncodetection neural electrodes, underscoring their tremendous potential\nfor applications in neuroscience research and brain–machine\ninterfaces.