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

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 microns in diameter.

Bioelectronic neural pixel: Chemical stimulation and electrical sensing at the same site

“…These results show that a single-cell-scale electrode has the ability to both record and chemically stimulate, demonstrating the local effects of therapeutic treatment, and opening a range of opportunities in basic neuroscience as well as medical technology development. one order of magnitude lower than bare Au, Pt, and Ir electrodes of similar dimensions at 1 kHz), with the low impedance being attributed partly to the high porosity, giving an increased electrochemical surface area (12)(13)(14). Additionally, with their mixed electronic and ionic conductivity and the soft mechanical properties that match those of the neural tissue, conducting polymers are ideally suited to obtain high signal-to-noise ratio recordings at the neural interface (15,16).…”

Prospects for Neuroprosthetics: Flexible Microelectrode Arrays with Polymer Conductors

“…Recent studies show the same effect for CPs. Ludwig et al reported on an about 10-fold decrease in impedance at 1 kHz for electrochemically deposited PEDOT coatings on Ø 15 µm Au recording electrodes, which reduced noise levels by about half (Ludwig et al, 2011). In earlier studies, the same effect was demonstrated for polypyrrole (PPy) (Cui et al, 2001).…”

System-on-Chip Considerations for Heterogeneous Integration of CMOS and Fluidic Bio-Interfaces

“…They decrease interfacial impedance and increase the charge capacity of the electrode. One example is poly(3, 4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS),which was found to increase the SNR for in-vivo implanted electrodes [72]. We found that PEDOT:PSS deposited on Au electrodes using the methods outlined in [71] resulted in a decrease in impedance of nearly two orders of magnitude [51].…”