title: Resistive and reactive changes to the impedance of intracortical microelectrodes can be mitigated with polyethylene glycol under acute in vitro and in vivo settings.
abstract: The reactive response of brain tissue to implantable intracortical microelectrodes is thought to negatively affect their recordable signal quality and impedance, resulting in unreliable longitudinal performance. The relationship between the progression of the reactive tissue into a glial scar and the decline in device performance is unclear. We show that exposure to a model protein solution in vitro and acute implantation result in both resistive and capacitive changes to electrode impedance, rather than purely resistive changes. We also show that applying 4000 MW polyethylene glycol (PEG) prevents impedance increases in vitro, and reduces the percent change in impedance in vivo following implantation. Our results highlight the importance of considering the contributions of non-cellular components to the decline in neural microelectrode performance, and present a proof of concept for using a simple dip-coated PEG film to modulate changes in microelectrode impedance.
authors.affiliation: Weldon School of Biomedical Engineering, Purdue University West Lafayette, IN, USA ; Physiological Sensing Facility at the Bindley Bioscience Center and Birck Nanotechnology Center, Purdue University West Lafayette, IN, USA.
authors.forename: Salah
authors.initials: S
authors.lastname: Sommakia
authors.affiliation: Department of Biological Sciences, Purdue University West Lafayette, IN, USA.
authors.forename: Janak
authors.initials: J
authors.lastname: Gaire
authors.affiliation: Weldon School of Biomedical Engineering, Purdue University West Lafayette, IN, USA ; Physiological Sensing Facility at the Bindley Bioscience Center and Birck Nanotechnology Center, Purdue University West Lafayette, IN, USA ; Department of Agricultural and Biological Engineering, Purdue University West Lafayette, IN, USA.
authors.forename: Jenna L
authors.initials: JL
authors.lastname: Rickus
authors.affiliation: Weldon School of Biomedical Engineering, Purdue University West Lafayette, IN, USA ; Department of Biological Sciences, Purdue University West Lafayette, IN, USA.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Otto
keywords: dip coating; foreign-body reaction; impedance spectroscopy; intracortical microelectrodes; polyethylene glycols