title: Performance of conducting polymer electrodes for stimulating neuroprosthetics.
abstract: OBJECTIVE
  Recent interest in the use of conducting polymers (CPs) for neural stimulation electrodes has been growing; however, concerns remain regarding the stability of coatings under stimulation conditions. These studies examine the factors of the CP and implant environment that affect coating stability. The CP poly(ethylene dioxythiophene) (PEDOT) is examined in comparison to platinum (Pt), to demonstrate the potential performance of these coatings in neuroprosthetic applications.
  
  
  METHODS
  PEDOT is coated on Pt microelectrode arrays and assessed in vitro for charge injection limit and long-term stability under stimulation in biologically relevant electrolytes. Physical and electrical stability of coatings following ethylene oxide (ETO) sterilization is established and efficacy of PEDOT as a visual prosthesis bioelectrode is assessed in the feline model.
  
  
  RESULTS
  It was demonstrated that PEDOT reduced the potential excursion at a Pt electrode interface by 72% in biologically relevant solutions. The charge injection limit of PEDOT for material stability was found to be on average 30× larger than Pt when tested in physiological saline and 20× larger than Pt when tested in protein supplemented media. Additionally stability of the coating was confirmed electrically and morphologically following ETO processing. It was demonstrated that PEDOT-coated electrodes had lower potential excursions in vivo and electrically evoked potentials (EEPs) could be detected within the visual cortex.
  
  
  CONCLUSIONS
  These studies demonstrate that PEDOT can be produced as a stable electrode coating which can be sterilized and perform effectively and safely in neuroprosthetic applications. Furthermore these findings address the necessity for characterizing in vitro properties of electrodes in biologically relevant milieu which mimic the in vivo environment more closely.
authors.affiliation: Graduate School of Biomedical Engineering, University of New South Wales, Sydney 2052, Australia. r.green@unsw.edu.au
authors.forename: R A
authors.initials: RA
authors.lastname: Green
authors.forename: P B
authors.initials: PB
authors.lastname: Matteucci
authors.forename: R T
authors.initials: RT
authors.lastname: Hassarati
authors.forename: B
authors.initials: B
authors.lastname: Giraud
authors.forename: C W D
authors.initials: CW
authors.lastname: Dodds
authors.forename: S
authors.initials: S
authors.lastname: Chen
authors.forename: P J
authors.initials: PJ
authors.lastname: Byrnes-Preston
authors.forename: G J
authors.initials: GJ
authors.lastname: Suaning
authors.forename: L A
authors.initials: LA
authors.lastname: Poole-Warren
authors.forename: N H
authors.initials: NH
authors.lastname: Lovell
mesh_terms: D000818:Animals; D002415:Cats; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D004553:Electric Conductivity; D008839:Microelectrodes / Q000592:standards; D011108:Polymers / Q000737:chemistry*; D014793:Visual Cortex / Q000502:physiology*; D057488:Visual Prosthesis / Q000737:chemistry* / Q000592:standards
chemical_list: D020099:Coated Materials, Biocompatible; D011108:Polymers