Chronic in vivo evaluation of PEDOT/CNT for stable neural recordings

December 26, 2015

Chronic in vivo evaluation of PEDOT/CNT for stable neural recordings https://www.embs.org/tbme/wp-content/uploads/sites/19/2015/12/B11BRAIN00072highlightsimage4.gif 170 177 IEEE Transactions on Biomedical Engineering (TBME) IEEE Transactions on Biomedical Engineering (TBME) //www.embs.org/tbme/wp-content/uploads/sites/19/2022/06/ieee-tbme-logo2x.png December 26, 2015 March 4, 2022

Takashi D.Y. Kozai, Kasey Catt, Zhanhong Du, Kyounghwan Na, Onnop Srivannavit, Razi-ul M. Haque, John Seymour, Kensall D Wise, Euisik Yoon, X. Tracy Cui, University of Pittsburgh, University of Michigan, ePack, Inc, Structured Microsystems LLC, USA,

Sub-cellular sized chronically implanted recording electrodes have demonstrated significant improvement in single-unit (SU) yield over larger recording probes. Additional work expands on this initial success by combining the subcellular fiber-like lattice structures with the design space versatility of silicon microfabrication to further improve the signal-to-noise ratio, density of electrodes, and stability of recorded units over months to years. However, ultra-small microelectrodes present very high impedance, which must be lowered for SU recordings. While poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrene sulfonate (PSS) coating has demonstrated great success in acute to early-chronic studies for lowering the electrode impedance, concern exists over long-term stability. Here, we demonstrate a new blend of PEDOT doped with carboxyl functionalized multi-walled carbon nanotubes (CNTs) which shows dramatic improvement over the traditional PEDOT/PSS formula. Lattice style subcellular electrode arrays were fabricated using previously established method. PEDOT was polymerized with carboxylic acid functionalized carbon nanotubes onto high impedance (8.0±0.1 MΩ: M±S.E.) 250 µm² gold recording sites. PEDOT/CNT coated subcellular electrodes demonstrated significant improvement in chronic spike recording stability over four months compared to PEDOT/PSS recording sites. These results demonstrate great promise for subcellular sized recording and stimulation electrodes and long-term stability. This project uses leading-edge biomaterials to develop chronic neural probes that are small (sub-cellular) with excellent electrical properties for stable long-term recordings. High density ultrasmall electrodes combined with advanced electrode surface modification are likely to make significant contributions to the development of long-term (permanent), high quality, and selective neural interfaces. www.BIONICLab.org

Keywords: Conductive Polymer, Brain-computer interface, multi-electrode array, neuroprosthetics, Neural Interface.

Takashi D.Y. Kozai

Takashi D.Y. Kozai received a B.A. Magna Cum Laude with Distinction in Molecular, Cellular, and Developmental Biology, and another B.A. with Distinction in Biochemistry from the University of Colorado, Boulder in 2005. He earned his M.S. (2007) and PhD (2011) degree in Biomedical Engineering from the University of Michigan, Ann Arbor. From 2007 to 2009 he also co-founded Fontis Biotechnologies a medical device startup for transdermal macromolecular drug delivery. From 2011 to 2013, he was a postdoctoral associate in the Department of Bioengineering at University of Pittsburgh. In 2013, he was appointed to Bioengineering to Research Assistant Professor. His primary interests include the areas of elucidating molecular and cellular pathways of brain injuries and diseases, implantable medical devices, biomaterials, and neurotechnology.

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