Faradaic electrochemistry at microcylinder, band, and tubular band electrodes

doi:10.1016/0368-1874(85)80136-2

Journal of Electroanalytical Chemistry and Interfacial Electrochemistry

Volume 185, Issue 2, 25 April 1985, Pages 285-295

https://doi.org/10.1016/0368-1874(85)80136-2 Get rights and content

Abstract

Current-time relationships of faradaic processes at microcylinder, band, and tubular band electrodes have been evaluated. Microcylinder electrodes were fabricated from platinum wires (5 μm radius) sealed in glass capillaries. Band and tubular electrodes were constructed with platinum sheets (∼ 20 μm width) or thin pieces of graphite (∼ 5 μm width) sealed between insulating mateials. The temporal response of the current at a microcylinder electrode for the reduction of ferricyanide in aqueous potassium chloride solutions is in excellent agreement with that predicted by equations derived for heat flux to a cylinder. An estimation of the magnitude and temporal properties of the measured current at a band electrode can be obtained when a hemicylinder geometry is assumed. The current respone is identical at band and tubular band electrodes even for the smallest tubular radius investigated, 0.54 mm. Cyclic voltammograms at electrodes of all three geometries show significant contributions from radial diffusion at slow scan rates (< 20 mV s⁻¹). The current at a graphite tubular band electrode was found to be independent of flow of solution through the electrode at flow rates up to 3 ml min⁻¹.

References (27)

B. Scharifker et al.
J. Electroanal. Chem.
(1981)
J. Heinze
J. Electroanal. Chem.
(1981)
K. Aoki et al.
J. Electroanal. Chem.
(1981)
D. Shoup et al.
J. Electroanal. Chem.
(1982)
K.B. Oldham
J. Electroanal. Chem.
(1981)
O.R. Brown
J. Electroanal. Chem.
(1972)
M.M. Stephens et al.
J. Electroanal. Chem.
(1984)
S.W. Barr et al.
J. Electroanal. Chem.
(1980)
R.M. Wightman
Anal. Chem.
(1981)
M.A. Dayton et al.
Anal. Chem.
(1980)

Y. Saito

Rev. Polarogr.

(1968)

M.A. Dayton et al.

Anal. Chem.

(1980)

Z. Gatus et al.

J. Electroanal. Chem.

(1982)

Cited by (134)

Precise and rapid solvent-assisted geometric protein self-patterning with submicron spatial resolution for scalable fabrication of microelectronic biosensors
2021, Biosensors and Bioelectronics
Precise and high-resolution coupling of functional proteins with micro-transducers is critical for the manufacture of miniaturized bioelectronic devices. Moreover, electrochemistry on microelectrodes has had a major impact on electrochemical analysis and sensor technologies, since the small size of microelectrode affects the radial diffusion flux of the analyte to deliver enhanced mass transport and electrode kinetics. However, a large technology gap has existed between the process technology associated with such microelectronics and the conventional bio-conjugation techniques that are generally used. Here, we report on a high-resolution and rapid geometric protein self-patterning (GPS) method using solvent-assisted protein-micelle adsorption printing to couple biomolecules onto microelectrodes with a minimum feature size of 5 μm and a printing time of about a minute. The GPS method is versatile for micropatterning various biomolecules including enzymes, antibodies and avidin-biotinylated proteins, delivering good geometric alignment and preserving biological functionality. We further demonstrated that enzyme-coupled microelectrodes for glucose detection exhibited good electrochemical performance which benefited from the GPS method to maximize effective signal transduction at the bio-interface. These microelectrode arrays maintained fast convergent analyte diffusion displaying typical steady-state I–V characteristics, fast response times, good linear sensitivity (0.103 nA mm⁻² mM⁻¹, R² = 0.995) and an ultra-wide linear dynamic range (2–100 mM). Our findings provide a new technical solution for the precise and accurate coupling of biomolecules to a microelectronic array with important implications for the scaleup and manufacture of diagnostics, biofuel cells and bioelectronic devices that could not be realized economically by other existing techniques.
Comparative chronoamperometry: Spheres, discs, cylinders and bands
2020, Journal of Electroanalytical Chemistry
A parameter, the diffusion indicator α, introduced in this work, is derived from chronoamperometric current responses to obtain comparative information about the diffusion of an electrochemically active species from/to an electrode. The α values are used to investigate the diffusion to four electrodes with different geometries: microsphere, microdisc, microcylinder, and microband electrodes based on literature analytical and empirical equations for their chronoamperometric currents and the associated concentration profiles extracted from new simulations. The values of α and their time evolution show the contrasting contribution of planar and convergent/divergent diffusion in the different geometries.
Reversible voltammetry at cylindrical electrodes: Validity of a one-dimensional model
2020, Journal of Electroanalytical Chemistry
The cyclic voltammetry of a reversible one-electron-transfer electrochemical reaction is investigated using finite difference simulations at three electrode geometries: an ‘infinitely long cylinder’ electrode featuring a cylindrical electrode with an infinite length, an ‘annular band’ electrode, whose band-shape electrochemically active area is located around an infinitely long insulating cylinder, and a ‘full cylinder’ electrode which resembles the microwire electrodes widely used in electrochemical experiments with both side and end active. Following the simulation of the infinitely long cylindrical electrode, a polynomial equation is introduced to describe the forward peak potentials at different scan rates. Based on further simulations of the other two electrodes, we find if the lengths of the latter are greater than ~ 10⁴ times the radius of the cylinders, the electrochemical reversible cyclic voltammetry of them can be well described by the infinitely long cylinder model with errors of less than 1%.
Characterising the nature of diffusion via a new indicator: Microcylinder and microring electrodes
2019, Journal of Electroanalytical Chemistry
Citation Excerpt :
Microelectrodes are of great importance to electrochemical studies of mass transport, reaction mechanisms and voltammetry as reviewed in the literature [1–7]. In particular, diffusion can be readily studied through microcylinder electrodes and microwire electrodes [8–32] due to their ease of fabrication and utilisation. The theoretical studies of diffusive fluxes towards microcylinder electrodes by Aoki et al. [8] and Szabo et al. [11] reported two approximate equations in 1985 and 1987, respectively, to describe the chronoamperometric currents towards infinitely long cylindrical electrodes.
An indicator to character diffusion is introduced to quantify the extent of linear and convergent diffusion in chronoamperometric currents. Simulated data for microcylinder and microring models is thus characterised and different time scales of diffusive fluxes from different spatial locations are revealed and discussed. Finally, the applicability of the Aoki equation [Journal of Electroanalytical Chemistry, 186, 79 (1985)] to the chronoamperometric currents for various cylinder-like models is explored and assessed.
Electrochemical behavior of a gold nanoring electrode microfabricated on a silicon micropillar
2019, Sensors and Actuators, B: Chemical
Citation Excerpt :
The band NE’s electroactive area is controlled by simply changing the thickness of the conductive thin film during the film deposition process. Compared to disk NEs, another common electrode geometry, band NEs permit a higher current density while maintaining the properties of radial-type diffusion [24,25]. The most noticeable feature of band NEs is the uniform distribution of current density across the surface, which greatly reduces the non-uniformity of charging [24,26–28].
We report on the microfabrication and characterization of a gold nanoring electrode (Au NRE) patterned on top of a silicon (Si) micropillar. An NRE of 165 ± 10 nm in width was micropatterned on 4.6 ± 1 μm diameter × 17.5 ± 2.5 μm long Si micropillar with an intervening 50 nm thick hafnium oxide insulating layer. Scanning electron microscopy and energy dispersive spectroscopy data confirmed excellent cylindricality of the micropillar with vertical sidewalls and a completely intact layer of Au NRE encompassing the entire micropillar perimeter. The electrochemical behavior of the Au NRE was characterized by a steady-state cyclic voltammogram with extremely high signal-to-noise ratios of 2500 and charging currents as small as 1.5 ± 0.3 pA. A “semicircle spectrum” from the Nyquist plot indicates a kinetically-controlled voltammetric current response, which is unique to nanoscale electrodes. The variations in the exchange current values, which are dependent on the NRE area and standard rate constant, place a greater emphasis on the isotropic gold wet etching process that defined the geometry of the Au NRE. Circuit fitting of the electrochemical impedance spectra suggests that the NRE geometry can be varied from inlaid to nanotrench with depths controllable by the etching process. This resulted in differing stead-state voltammetric currents and interfacial properties in terms of charge transfer resistance, constant phase element and trench resistance values. The applicability of Au NREs to electrochemical sensing is demonstrated by detecting lead, a neurotoxin at 100 ppb levels. Also, by surface-modification with multi-walled carbon nanotubes, dopamine, a neurochemical implicated in various brain disorders, is detected at a sensitivity as low as 100 nM with 1000-fold selectivity versus common interferents. The flexibility of the microfabrication approach allows for the creation of multiple NREs of controllable width and nanometer spacing on a single micropillar. This capability and in particular where the NRE is micropatterned on three-dimensional microstructures as will be reported herein, facilitates unique electroanalytical capabilities such as intracellular electrochemistry and highly multiplexed detection for emerging biological applications.
Use of interelectrode material transfer of nickel and copper‑nickel alloy to carbon fibers to assemble miniature glucose sensors
2018, Journal of Electroanalytical Chemistry
Electrochemical deposition of the material released by anodizing nickel and copper nickel alloy in pure water onto carbon fiber microelectrodes was used to assemble miniature glucose sensors. The composition and morphology of the deposits was investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The deposition of anode-derived materials proceeded by two consecutive mechanisms, which are explained in detail. The electrochemical properties of the designed electrodes were subsequently investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The different Ni- and mixed CuNi-modified microelectrodes were examined as glucose sensors and the best performing electrodes based on the alloyed deposit exhibited very high sensitivity (5720 μA mM⁻¹ cm⁻²), low detection limit (0.3 μM) and ability to quantify glucose in blood serum.

View all citing articles on Scopus

View full text