title: Improving the performance of poly(3,4-ethylenedioxythiophene) for brain-machine interface applications.
abstract: Conducting polymers, especially poly(3,4-ethylenedioxythiophene) (PEDOT) based materials, are important for developing highly sensitive and microscale neural probes. In the present work, we show that the conductivity and stability of PEDOT can be significantly increased by switching the widely used counter anion poly(styrenesulfonate) (PSS) to the smaller tetrafluoroborate (TFB) anion during the electrodeposition of the polymer. Time-dependent impedance measurements of polymer modified implantable microwires were conducted in physiological buffer solutions under accelerated aging conditions and the relative stability of PEDOT:PSS and PEDOT:TFB modified microwires was compared over time. This study was also extended to carbon nanotube (CNT) incorporated PEDOT:PSS which, according to some reports, is claimed to enhance the stability and electrical performance of the polymer. However, no noticeable difference was observed between PEDOT:PSS and CNT:PEDOT:PSS in our measurements. At the biologically relevant frequency of 1kHz, PEDOT:TFB modified microwires exhibit approximately one order of magnitude higher conductivity and demonstrate enhanced stability over both PEDOT:PSS and CNT:PEDOT:PSS modified microwires. In addition, PEDOT:TFB is not neurotoxic and we show the proof-of-concept for both in vitro and in vivo neuronal recordings using PEDOT:TFB modified microelectrode arrays and chronic electrodes, respectively. Our findings suggest that PEDOT:TFB is a promising conductive polymer coating for the recording of neural activities.
authors.affiliation: Department of Bioengineering, George Mason University, Fairfax, VA 22030, USA. Electronic address: hmandal@gmu.edu.
authors.forename: Himadri S
authors.initials: HS
authors.lastname: Mandal
authors.affiliation: Department of Molecular Neuroscience, The Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA.
authors.forename: Gretchen L
authors.initials: GL
authors.lastname: Knaack
authors.affiliation: Department of Electrical and Computer Engineering, George Mason University, Fairfax, VA 22030, USA.
authors.forename: Hamid
authors.initials: H
authors.lastname: Charkhkar
authors.affiliation: Department of Molecular Neuroscience, The Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: McHail
authors.affiliation: Department of Bioengineering, George Mason University, Fairfax, VA 22030, USA.
authors.forename: Jemika S
authors.initials: JS
authors.lastname: Kastee
authors.affiliation: Department of Molecular Neuroscience, The Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA.
authors.forename: Theodore C
authors.initials: TC
authors.lastname: Dumas
authors.affiliation: Department of Electrical and Computer Engineering, George Mason University, Fairfax, VA 22030, USA.
authors.forename: Nathalia
authors.initials: N
authors.lastname: Peixoto
authors.affiliation: Department of Chemistry, Georgetown University, Washington, DC 20057, USA.
authors.forename: Judith F
authors.initials: JF
authors.lastname: Rubinson
authors.affiliation: Department of Bioengineering, George Mason University, Fairfax, VA 22030, USA; Department of Electrical and Computer Engineering, George Mason University, Fairfax, VA 22030, USA.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Pancrazio
mesh_terms: D062207:Brain-Computer Interfaces; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D011108:Polymers / Q000737:chemistry*
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D011108:Polymers; C121383:poly(3,4-ethylene dioxythiophene)
keywords: Action potential; Carbon nanotube; Electrochemical impedance; Neural probe; PEDOT