Transparent and flexible materials are attractive for a wide range of emerging bioelectronic
applications. These include neural interfacing devices for both recording and stimulation,
where low electrochemical electrode impedance is valuable. Here the conducting polymer
poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) is utilized to
fabricate electrodes that are small enough to allow unencumbered optical access for
imaging a large cell population with two-photon (2P) microscopy, yet provide low impedance
for simultaneous high quality recordings of neural activity in vivo. To demonstrate
this, pathophysiological activity was induced in the mouse cortex using 4-aminopyridine
(4AP) and the resulting electrical activity was detected with the PEDOT:PSS-based
probe while imaging calcium activity directly below the probe area. The induced calcium
activity of the neuronal network as measured by the fluorescence change in the cells
correlated well with the electrophysiological recordings from the cortical grid of
PEDOT:PSS microelectrodes. Our approach provides a valuable vehicle for complementing
classical high temporal resolution electrophysiological analysis with optical imaging.
