Transparent microelectrodes that facilitate simultaneous optical and electrophysiological interfacing are desirable tools for neuroscience. Electrodes made from transparent conductors such as graphene and indium tin oxide (ITO) show promise but are often limited by poor charge-transfer properties. Herein, microelectrodes are demonstrated that take advantage of the transparency and volumetric capacitance of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). Ring-shaped microelectrodes are fabricated by inkjet-printing PEDOT:PSS, encapsulating with Parylene C, and then exposing a contact site that is much smaller than the microelectrode outer diameter. This unique structure allows the encapsulated portion of the microelectrode volume surrounding the contact site to participate in signal transduction, which reduces impedance and enhances charge storage capacity. While using the same 100 μm diameter contact site, increasing the outer diameter of the encapsulated electrode from 300 to 550 μm reduces the impedance from 294 ± 21 to 98 ± 2 kΩ, respectively, at 1 Hz. Similarly, the charge storage capacity is enhanced from 6 to 21 mC cm−2. The PEDOT:PSS microelectrodes provide a low-haze, high-transmittance optical interface, demonstrating their suitability for optical neuroscience applications. They remain functional after a million 1 V stimulation cycles, up to 600 μA of stimulation current, and more than 1000 mechanical bending cycles.
|Original language||English (US)|
|Journal||Physica Status Solidi (A) Applications and Materials Science|
|State||Published - May 2022|
Bibliographical noteFunding Information:
Research reported in this publication was supported by the Institute of Neurological Disorders and Stroke at the National Institutes of Health under award number R01NS111028. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Portions of this work were conducted in the Minnesota Nano Center, which is supported by the National Science Foundation through the National Nano Coordinated Infrastructure (NNCI) Network, Award Number ECCS‐1542202. This material is based upon work supported by the National Science Foundation under grant no. DGE‐1069104. The authors would like to acknowledge R. Connell and B. Cote in the Ferry Lab at the University of Minnesota for the use of their UV–vis spectrometer. The authors would also like to acknowledge S. B. Kodandaramaiah and Z. S. Navabi for helpful discussion regarding microelectrode design.
© 2022 The Authors. physica status solidi (a) applications and materials science published by Wiley-VCH GmbH
- impedance modeling
- transparent microelectrodes
- volumetric capacitance