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

Abstract

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(3,4ethylenedioxythiophene) (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 LiClO 4 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:LiClO 4 . 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-μm-deep phosphate-buffered saline were 50 μm/s and 210 s at 50 μA and 820 μm/s and 9 s at 800 μA, respectively, between parallel-band-electrodes, modified with the thickest films.

Applications of magnetic and electromagnetic forces in micro-analytical systems

“…266 Recently, this group successfully eliminated the need to add redox species to the solution for the MHD pumping by the use of the electrode modified with a conductive polymer, thus removing interferences with detection, sample, and reagents for lab-on-a-chip applications. 267,268 A conductive polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), was electropolymerized on microband gold electrodes in a solution consisting of 0.010 M EDOT, 0.010 M SDS, and 0.100 M KCl (ref. 267) or in solutions containing 0.010 M EDOT and 0.100 M TBAPF 6 or LiClO 4 electrolyte, respectively, in propylene carbonate.…”

“…267) or in solutions containing 0.010 M EDOT and 0.100 M TBAPF 6 or LiClO 4 electrolyte, respectively, in propylene carbonate. 268 At the anode, PEDOT was changed from the neutral to oxidized state, which was associated with ions moving into or out of the film from the surrounding solution to compensate for the change in charge. At the cathode, PEDOT was converted from its oxidized state to its neutral state, causing the anions to leave the PEDOT film and enter the surrounding solution.…”

Characterization of Nanoparticles in Diverse Mixtures Using Localized Surface Plasmon Resonance and Nanoparticle Tracking by Dark-Field Microscopy with Redox Magnetohydrodynamics Microfluidics

“…The outermost band electrodes and other smaller electrodes on the chip were not used in the studies reported here. A film of PEDOT was sequentially electropolymerized onto each band electrode based on a previously described procedure 53 (modifications to the referenced procedure are in the Supporting Information) and used as a working electrode (WE). Cyclic voltammetry (CV) was performed with a PalmSens4 galvanostat/ potentiostat (Palmsens, Houten, the Netherlands), a platinum counter electrode (CE), and a Ag/AgCl, 3 M KCl reference electrode (RE).…”

“…A sample solution is added to a chip patterned with individually addressable electrodes and placed adjacent to a permanent magnet. When an electronic current is passed between electrodes which have been modified with the conducting polymer poly­(3,4-ethylenedioxythiophene) (PEDOT), the polymer oxidizes at the anode, attracting anions from the electrolyte solution to compensate charge (and repels cations) and the opposite process occurs at the cathode, thus creating the ionic current. , The uniform horizontal flow profile of RMHD has enabled imaging of leukocytes of 10s μm in a flowing sample with fluorescence epitaxial light sheet confocal microscopy . RMHD has also been combined with fluorescence correlation spectroscopy to attain flow profiles and diffusion coefficients of particles down to 0.1 μm but without direct imaging capabilities.…”

PEDOT-Type Conducting Polymers/Black TiO2 Composites for Electrochemical Determination of Cd2+ and Pb2+

“…15,16 Among them, π-conjugated polymers have been recognized as excellent candidates for high-performance material with particular structure and excellent optical, electrochemical properties. [17][18][19] The combination of π-conjugated polymers with nano-TiO 2 can bring an improvement of electrochemical behaviors. 20 The PEDOT-type conducting polymers, such as PEDOT and PProDOT are particularly important in practical applications due to their low oxidation potential, good electrical conductivity and good stability.…”