Support-Free PEDOT:PSS Fibers as Multifunctional Microelectrodes for In Vivo Neural Recording and Modulation.

In vivo microelectrodes are essential for neuroscience studies. However, development of microelectrodes with both flexibility and multifunctionality for recording chemical and electrical signals in the same extracellular microspace and modulating neural activity remains challenging. Here, we find that pure PEDOT:PSS fibers (i.e., support-free) exhibit high conductivity, fast heterogeneous electron transfer, and suitable charge storage and injection capabilities, and can thus directly act as microelectrodes not only for chemical and electrophysiological recording in the same extracellular microspace, but also for electromodulation of neural microcircuit activity. Moreover, the microelectrodes mechanically match with neural tissues, exhibiting less foreign body responses. Given the multifunctionality, flexibility, and biocompatibility, the support-free PEDOT:PSS-based microelectrodes offer a new avenue to microelectrode technology for neuroscience research, diagnostics and therapeutics.