Electrochemical synthesis and characterization of poly(3,4-ethylenedioxythiophene) in ionic liquids with bulky organic anions

Danielsson, Petter; Bobacka, Johan; Ivaska, Ari

doi:10.1007/s10008-004-0549-2

Cited by 54 publications

(48 citation statements)

References 12 publications

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“…PEDOT:fibrinogen overall has the same behavior for increasing frequencies but there is also a high frequency semicircle seen ͑Ͼ440 Hz͒ similar to the findings presented by Danielsson et al 34 ͑2004͒ for PEDOT studied in bulky organic liquids and by Cui et al 17 ͑2001͒ for PPy doped with a silklike ProNectin F. At very high frequencies ͑Ͼ2300 Hz͒ a slight semicircle can be seen also for the thicker films ͑more than 1 mC/ mm 2 ͒ of PEDOT:HA. Apparently some processes that were not detectable for PEDOT:PSS or PEDOT-:heparin have here become slow enough to be visible also in the frequency range studied here.…”

Section: A Eissupporting

confidence: 84%

“…The model suggested by Bobacka et al 11 containing the solution resistance in series with a capacitance and the bounded Warburg diffusion element ͑here model 1͒ did not provide good fits ͑ 2 Ͼ 0.28͒ to experimental data, especially in the high frequency semicircular region, and we therefore chose the extended model suggested by Danielsson et al, 34 here denoted model 2, containing also a capacitor in parallel with a resistance ͑Fig. 6͒.…”

Section: B Equivalent Circuitmentioning

confidence: 99%

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Composite biomolecule/PEDOT materials for neural electrodes

2008

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Electrodes intended for neural communication must be designed to meet both the electrochemical and biological requirements essential for long term functionality. Metallic electrode materials have been found inadequate to meet these requirements and therefore conducting polymers for neural electrodes have emerged as a field of interest. One clear advantage with polymer electrodes is the possibility to tailor the material to have optimal biomechanical and chemical properties for certain applications. To identify and evaluate new materials for neural communication electrodes, three charged biomolecules, fibrinogen, hyaluronic acid (HA), and heparin are used as counterions in the electrochemical polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT). The resulting material is evaluated electrochemically and the amount of exposed biomolecule on the surface is quantified. PEDOT:biomolecule surfaces are also studied with static contact angle measurements as well as scanning electron microscopy and compared to surfaces of PEDOT electrochemically deposited with surfactant counterion polystyrene sulphonate (PSS). Electrochemical measurements show that PEDOT:heparin and PEDOT:HA, both have the electrochemical properties required for neural electrodes, and PEDOT:heparin also compares well to PEDOT:PSS. PEDOT:fibrinogen is found less suitable as neural electrode material.

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Section: A Eissupporting

confidence: 84%

Section: B Equivalent Circuitmentioning

confidence: 99%

Composite biomolecule/PEDOT materials for neural electrodes

2008

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“…As discussed earlier, a number of previous studies have used equivalent circuit modeling to interpret the impedance response of bioelectrodes and CPs [28][29][30]32,33]. In this study, a more in details equivalent circuit model is proposed to characterize impedance of the electrode-CPelectrolyte interface.…”

Section: Equivalent Circuit Modelingmentioning

confidence: 99%

Experimental and theoretical characterization of implantable neural microelectrodes modified with conducting polymer nanotubes

2008

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Neural prostheses transduce bioelectric signals to electronic signals at the interface between neural tissue and neural microelectrodes. A low impedance electrode-tissue interface is important for the quality of signal during recording as well as quantity of applied charge density during stimulation. However, neural microelectrode sites exhibit high impedance because of their small geometric surface area. Here we analyze nanostructured-conducting polymers that can be used to significantly decrease the impedance of microelectrode typically by about two orders of magnitude and increase the charge transfer capacity of microelectrodes by three orders of magnitude. In this study poly (pyrrole) (PPy) and poly(3, 4-ethylenedioxythiophene) (PEDOT) nanotubes were electrochemically polymerized on the surface of neural microelectrode sites (1250 μm 2 ). An equivalent circuit model comprising a coating capacitance in parallel with a pore resistance and interface impedance in series was developed and fitted to experimental results to characterize the physical and electrical properties of the interface. To confirm that the fitting parameters correlate with physical quantities of interface, theoretical equations were used to calculate the parameter values thereby validating the proposed model. Finally, an apparent diffusion coefficient was calculated for PPy film (29.2 ± 1.1 cm 2 /s), PPy nanotubes (72.4 ± 3.3 cm 2 /s), PEDOT film (7.4 ± 2.1 cm 2 /s), and PEDOT nanotubes (13.0 ± 1.8 cm 2 /s). The apparent diffusion coefficient of conducting polymer nanotubes was larger than the corresponding conducting polymer films.

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“…Growth of conducting polymers at reduced temperatures (as low as −28 • C) [4,24] in molecular solvent systems is generally accepted to result in smoother, more conductive films, but we have found that in ionic liquids the significant increase in the viscosity can be problematic. In addition, the temperature used for the conducting polymer synthesis may be limited by the melting point of the ionic liquid [25].…”

Section: Temperaturementioning

confidence: 99%