Chip-Scale Electrodeposition and Analysis of Poly(3,4-ethylenedioxythiophene) (PEDOT) Films for Enhanced and Sustained Microfluidics Using DC-Redox-Magnetohydrodynamics

by Khan, Foysal Z.; Fritsch, Ingrid

Redox-magnetohydrodynamics (R-MHD) microfluidics precisely manipulates fluid flow through strategic placement/activation of electrodes and magnetic fields. This paper evaluates various conditions of potentiodynamic electrodeposition of poly(3,4-ethylenedioxythiophene) (PEDOT) films on chip-based, gold electrodes to attain maximum current and charge density, which correlate directly to R-MHD pumping speed and duration in a single direction, respectively. Electrodeposition of PEDOT was controlled by cyclic voltammetry (CV) (5, 50, and 100 mV/s) in propylene carbonate (PC) solutions of monomer and TBAPF(6) or LiClO4 electrolyte. The maximum charge is directly proportional to cycle number and inversely proportional to scan rate (i.e. time spent oxidizing monomer). Thicker and rougher films formed from PC:TBAPF(6), compared to PC:LiClO4. CV, chronoamperometry (CA), chronopotentiometry, and impedance spectroscopy assessed the electrochemical performance of films in aqueous electrolytes. The maximum current during CA in a given aqueous electrolyte for PEDOT films was independent of electrodeposition parameters and thickness and increased linearly with ionic strength. A three-stage model describes the oxidative response of thick PEDOT films. R-MHD fluid speeds and pumping durations at 0.37 T in 780-mu m-deep phosphate-buffered saline were 50 mu m/s and 210 s at 50 mu A and 820 mu m/s and 9 s at 800 mu A, respectively, between parallel-band-electrodes, modified with the thickest films. (C) The Author(s) 2019. Published by ECS.

Journal
Journal of the Electrochemical Society
Volume
166
Issue
13
Year
2019
Start Page
H615-H627
ISBN/ISSN
0013-4651; 1945-7111
DOI
10.1149/2.0811913jes