Abstract
Coating microelectrodes with conductive polymer is widely recognized to decrease impedance and improve performance of implantable neural devices during recording and stimulation. A concern for wide-spread use of this approach is shelf-life, i.e., the electrochemical stability of the coated microelectrodes prior to use. In this work, we investigated the possibility of using the freeze-drying process in order to retain the native low impedance state and, thereby, improve the shelf-life of conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT)-PSS modified neural electrodes. Control PEDOT-PSS coated microelectrodes demonstrated a significant increase in impedance at 1 kHz after 41–50 days of room temperature storage. Based on equivalent circuit modeling derived from electrochemical impedance spectroscopy, this increase in impedance could be largely attributed to a decrease in the interfacial capacitance consistent with a collapse and closing of the porous structure of the polymeric coating. Time-dependent electrochemical impedance measurements revealed higher stability of the freeze-dried coated microelectrodes compared to the controls, such that impedance values after 41–50 days appeared to be indistinguishable from the initial levels. This suggests that freeze drying PEDOT-PSS coated microelectrodes correlates with enhanced electrochemical stability during shelf storage.
Highlights
Conductive polymer (CP) modified microelectrodes are promising for developing small but sensitive and powerful neural interfaces for recording and stimulation [1,2,3,4,5,6,7,8]
In our previous reports [7,8] on the mechanistic investigation of the solution aging process in PEDOT modified neural electrodes, we demonstrated a direct relationship between the time-dependent increase in the electrode impedance and the gradual decrease in the electrochemically active surface area due to the collapse of the porous polymeric morphology
A total of 50 commercially available implantable Pt/Ir microwire electrodes were electrochemically modified with PEDOT-Poly(sodium 4-styrenesulfonate) (PSS)
Summary
Conductive polymer (CP) modified microelectrodes are promising for developing small but sensitive and powerful neural interfaces for recording and stimulation [1,2,3,4,5,6,7,8]. In our previous reports [7,8] on the mechanistic investigation of the solution aging process in PEDOT modified neural electrodes, we demonstrated a direct relationship between the time-dependent increase in the electrode impedance and the gradual decrease in the electrochemically active surface area due to the collapse of the porous polymeric morphology. Based on these observations, we suspected that a similar type of mechanism could be involved behind the low shelf-life of PEDOT modified electrodes.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
