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

Blackrock Microsystems, 630 Komas Dr #200, Salt Lake City, UT 84108, USA
System of Systems Analytics, 11250 Waples Mill Road, Fairfax, VA 22030, USA
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
Bioengineering 2015, 2(3), 176-183;
Received: 29 June 2015 / Accepted: 4 August 2015 / Published: 7 August 2015
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. View Full-Text
Keywords: conductive polymer; PEDOT; microwires; impedance; neural electrode conductive polymer; PEDOT; microwires; impedance; neural electrode
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MDPI and ACS Style

Mandal, H.S.; Cliff, R.O.; Pancrazio, J.J. Freeze Drying Improves the Shelf-Life of Conductive Polymer Modified Neural Electrodes. Bioengineering 2015, 2, 176-183.

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