Poly(3,4-ethylenedioxythiophene) (PEDOT) polymer coatings facilitate smaller neural recording electrodes

TLDR

Smaller electrode sites allow denser arrays and reduced probe size, which lowers immune response and improves long‑term implant viability. The study examined whether PEDOT coating could reduce impedance of small gold electrodes beyond the effective recording range. PEDOT was applied to small gold electrodes to lower their impedance. PEDOT‑coated electrodes recorded high‑quality neural activity with a lower noise floor, whereas control electrodes failed, demonstrating that PEDOT enables functional 15 µm diameter designs.

Abstract

We investigated using poly(3,4-ethylenedioxythiophene) (PEDOT) to lower the impedance of small, gold recording electrodes with initial impedances outside of the effective recording range. Smaller electrode sites enable more densely packed arrays, increasing the number of input and output channels to and from the brain. Moreover, smaller electrode sizes promote smaller probe designs; decreasing the dimensions of the implanted probe has been demonstrated to decrease the inherent immune response, a known contributor to the failure of long-term implants. As expected, chronically implanted control electrodes were unable to record well-isolated unit activity, primarily as a result of a dramatically increased noise floor. Conversely, electrodes coated with PEDOT consistently recorded high-quality neural activity, and exhibited a much lower noise floor than controls. These results demonstrate that PEDOT coatings enable electrode designs 15 µm in diameter.