Freeze Drying Improves the Shelf-Life of Conductive Polymer Modified Neural ElectrodesReport as inadecuate


Freeze Drying Improves the Shelf-Life of Conductive Polymer Modified Neural Electrodes


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1

Blackrock Microsystems, 630 Komas Dr #200, Salt Lake City, UT 84108, USA

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System of Systems Analytics, 11250 Waples Mill Road, Fairfax, VA 22030, USA

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Department of Bioengineering, Volgenau School of Engineering, George Mason University, 4400 University Drive, MS 1G5, Fairfax, VA 22030, USA





*

Author to whom correspondence should be addressed.



Academic Editor: Anthony Guiseppi-Elie

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 poly3,4-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. View Full-Text

Keywords: conductive polymer; PEDOT; microwires; impedance; neural electrode conductive polymer; PEDOT; microwires; impedance; neural electrode





Author: Himadri S. Mandal 1,* , Richard O. Cliff 2 and Joseph J. Pancrazio 3

Source: http://mdpi.com/



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