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Special Issue "Ultramicroelectrode Electrochemistry - Theory and Applications"

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Chemical Sensors".

Deadline for manuscript submissions: closed (31 August 2013)

Special Issue Editor

Guest Editor
Prof. Dr. Mike Lyons (Website)

Trinity College Dublin, School of Chemistry, The University of Dublin, College Green, Dublin 2, Ireland
Phone: 00353872433576
Fax: +353 1 671 2826
Interests: electroactive polymer electrochemistry; chemically modified electrodes; mathematical modelling of electrochemical systems; electrochemical energy conversion; electrocatalysis; metal oxide electrochemistry; ultramicroelectrode electrochemistry

Special Issue Information

Dear Colleagues,

Ultramicroelectrodes (UMEs) have been used in electrochemistry for more than twenty five years and much has been accomplished in this time both from the theoretical and applications viewpoint. UMEs are electrodes with characteristic dimensions on the micrometer or sub-micrometer scale. The current push is to make the size scale of microelectrodes still smaller and in some cases electrodes of a nanometer scale have been developed. Small size implies faster double layer charging, reduced Ohmic loss and high mass transport rates. Forster and Keyes (Forster, R.J.; Keyes, T.E. In Handbook of Electrochemistry; Zoski, C.G., Ed.; Elsevier: Amsterdam, The Netherlands, 2007; Chapter 6, pp. 155-188) have correctly noted that the latter properties have resulted in the extension of electrochemical boundaries into ultra small length scales, and nanosecond timescales with the resulting revolutionary advance in the measurement of kinetic, thermodynamic and electroanalytical measurements.

The time is now right to take stock of what has been accomplished both in the development of theory to describe the behavior of UMEs and in the application of the latter to electrochemical sensors and electroanalysis. The forthcoming special issue of Sensors entitled ‘Ultramicroelectrode Electrochemistry—Theory and Applications’ will serve as a forum to record recent developments, to present an overview of past accomplishments, and to suggest future directions in this exciting area.

The deadline for submissions is 31 August 2013. All papers submitted and accepted for publication before this date will be immediately published and gathered together on the website of the special issue. Research articles, review articles as well as communications are invited. Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere. All manuscripts are refereed through a peer review process. Sensors is an international peer-reviewed Open Access monthly journal published by MDPI.

Dr. Mike Lyons
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs).


Published Papers (7 papers)

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Research

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Open AccessArticle Rapid Detection of Viable Microorganisms Based on a Plate Count Technique Using Arrayed Microelectrodes
Sensors 2013, 13(7), 8188-8198; doi:10.3390/s130708188
Received: 17 April 2013 / Revised: 22 May 2013 / Accepted: 6 June 2013 / Published: 26 June 2013
Cited by 2 | PDF Full-text (424 KB) | HTML Full-text | XML Full-text
Abstract
Development of a miniaturized biosensor system that can be used for rapid detection and counting of microorganisms in food or water samples is described. The developed microsystem employs a highly sensitive impedimetric array of biosensors to monitor the growth of bacterial colonies [...] Read more.
Development of a miniaturized biosensor system that can be used for rapid detection and counting of microorganisms in food or water samples is described. The developed microsystem employs a highly sensitive impedimetric array of biosensors to monitor the growth of bacterial colonies that are dispersed across an agar growth medium. To use the system, a sample containing the bacteria is cultured above the agar layer. Using a multiplexing network, the electrical properties of the medium at different locations are continuously measured, recorded, and compared against a baseline signal. Variations of signals from different biosensors are used to reveal the presence of bacteria in the sample, as well as the locations of bacterial colonies across the biochip. This technique forms the basis for a label-free bacterial detection for rapid analysis of food samples, reducing the detection time by at least a factor of four compared to the current required incubation times of 24 to 72 hours for plate count techniques. The developed microsystem has the potential for miniaturization to a stage where it could be deployed for rapid analysis of food samples at commercial scale at laboratories, food processing facilities, and retailers. Full article
(This article belongs to the Special Issue Ultramicroelectrode Electrochemistry - Theory and Applications)
Open AccessArticle Fabrication of a Polyaniline Ultramicroelectrode via a Self Assembled Monolayer Modified Gold Electrode
Sensors 2013, 13(7), 8079-8094; doi:10.3390/s130708079
Received: 16 April 2013 / Revised: 14 June 2013 / Accepted: 18 June 2013 / Published: 24 June 2013
Cited by 1 | PDF Full-text (926 KB) | HTML Full-text | XML Full-text
Abstract
Herein, we report a simple and inexpensive way for the fabrication of an ultramicroelectrode and present its characterization by electrochemical techniques. The fabrication of polyaniline UME involves only two steps: modification of a gold (Au) electrode by self assembled monolayers (SAM) and [...] Read more.
Herein, we report a simple and inexpensive way for the fabrication of an ultramicroelectrode and present its characterization by electrochemical techniques. The fabrication of polyaniline UME involves only two steps: modification of a gold (Au) electrode by self assembled monolayers (SAM) and then electrodeposition of polyaniline film on this thiol-coated Au electrode by using cyclic voltammetry and constant potential electrolysis methods. Two types of self-assembled monolayers (4-mercapto-1-butanol, MB, and 11-mercaptoundecanoic acid, MUA) were used, respectively, to see the effect of chain length on microelectrode formation. Microelectrode fabrication and utility of the surface was investigated by cyclic voltammetric measurements in a redox probe. The thus prepared polyaniline microelectrode was then used for DNA immobilization. Discrimination between double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA) was obtained with enhanced electrochemical signals compared to a polyaniline-coated Au electrode. Different modifications on the electrode surfaces were examined using scanning electron microscopy (SEM). Full article
(This article belongs to the Special Issue Ultramicroelectrode Electrochemistry - Theory and Applications)
Open AccessArticle Development of Amperometric Biosensors Based on Nanostructured Tyrosinase-Conducting Polymer Composite Electrodes
Sensors 2013, 13(5), 6759-6774; doi:10.3390/s130506759
Received: 18 March 2013 / Revised: 25 April 2013 / Accepted: 28 April 2013 / Published: 21 May 2013
Cited by 15 | PDF Full-text (903 KB) | HTML Full-text | XML Full-text
Abstract
Bio-composite coatings consisting of poly(3,4-ethylenedioxythiophene) (PEDOT) and tyrosinase (Ty) were successfully electrodeposited on conventional size gold (Au) disk electrodes and microelectrode arrays using sinusoidal voltages. Electrochemical polymerization of the corresponding monomer was carried out in the presence of various Ty amounts in [...] Read more.
Bio-composite coatings consisting of poly(3,4-ethylenedioxythiophene) (PEDOT) and tyrosinase (Ty) were successfully electrodeposited on conventional size gold (Au) disk electrodes and microelectrode arrays using sinusoidal voltages. Electrochemical polymerization of the corresponding monomer was carried out in the presence of various Ty amounts in aqueous buffered solutions. The bio-composite coatings prepared using sinusoidal voltages and potentiostatic electrodeposition methods were compared in terms of morphology, electrochemical properties, and biocatalytic activity towards various analytes. The amperometric biosensors were tested in dopamine (DA) and catechol (CT) electroanalysis in aqueous buffered solutions. The analytical performance of the developed biosensors was investigated in terms of linear response range, detection limit, sensitivity, and repeatability. A semi-quantitative multi-analyte procedure for simultaneous determination of DA and CT was developed. The amperometric biosensor prepared using sinusoidal voltages showed much better analytical performance. The Au disk biosensor obtained by 50 mV alternating voltage amplitude displayed a linear response for DA concentrations ranging from 10 to 300 μM, with a detection limit of 4.18 μM. Full article
(This article belongs to the Special Issue Ultramicroelectrode Electrochemistry - Theory and Applications)
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Open AccessArticle The Long-Time Chronoamperometric Current at an Inlaid Microband (or Laminar) Electrode
Sensors 2013, 13(1), 626-647; doi:10.3390/s130100626
Received: 27 November 2012 / Revised: 20 December 2012 / Accepted: 21 December 2012 / Published: 4 January 2013
PDF Full-text (511 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this article, we derive an approximate asymptotic analytical expression for the long-time chronoamperometric current response at an inlaid microband (or laminar) electrode. The expression is applicable when the length of the microband is much greater than the width, so that the [...] Read more.
In this article, we derive an approximate asymptotic analytical expression for the long-time chronoamperometric current response at an inlaid microband (or laminar) electrode. The expression is applicable when the length of the microband is much greater than the width, so that the diffusion of the electrochemical species can be regarded as two-dimensional. We extend the previously known result for the diffusion-limited current response (Aoki, K. et al. J. Electroanal. Chem. 1987, 225, 19–32 and Phillips, C.G. J. Electroanal. Chem. 1992, 333, 11–32) to accommodate quasi-reversible reactions and unequal diffusion coefficients of the oxidant and the reductant. Comparison with numerical calculations validates the analytical expression, and we demonstrate that unequal diffusion coefficients can substantially change the current response. Finally, we discuss the form of the long-time current response for a one-step, one-electron redox reaction if the rate constants are modelled in the Butler–Volmer framework, and indicate the importance of choosing the width of the microband appropriately to allow accurate experimental determination of the standard kinetic rate constant and the electron transfer coefficient. Full article
(This article belongs to the Special Issue Ultramicroelectrode Electrochemistry - Theory and Applications)
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Review

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Open AccessReview Microelectrode Arrays with Overlapped Diffusion Layers as Electroanalytical Detectors: Theory and Basic Applications
Sensors 2013, 13(10), 13659-13684; doi:10.3390/s131013659
Received: 23 July 2013 / Revised: 14 August 2013 / Accepted: 28 August 2013 / Published: 11 October 2013
Cited by 10 | PDF Full-text (903 KB) | HTML Full-text | XML Full-text
Abstract
This contribution contains a survey of basic literature dealing with arrays of microelectrodes with overlapping diffusion layers as prospective tools in contemporary electrochemistry. Photolithographic thin layer technology allows the fabrication of sensors of micrometric dimensions separated with a very small gap. This [...] Read more.
This contribution contains a survey of basic literature dealing with arrays of microelectrodes with overlapping diffusion layers as prospective tools in contemporary electrochemistry. Photolithographic thin layer technology allows the fabrication of sensors of micrometric dimensions separated with a very small gap. This fact allows the diffusion layers of single microelectrodes to overlap as members of the array. Various basic types of microelectrode arrays with interacting diffusion layers are described and their analytical abilities are accented. Theoretical approaches to diffusion layer overlapping and the consequences of close constitution effects such as collection efficiency and redox cycling are discussed. Examples of basis applications in electroanalytical chemistry such as amperometric detectors in HPLC and substitutional stripping voltammetry are also given. Full article
(This article belongs to the Special Issue Ultramicroelectrode Electrochemistry - Theory and Applications)
Open AccessReview Microarray Dot Electrodes Utilizing Dielectrophoresis for Cell Characterization
Sensors 2013, 13(7), 9029-9046; doi:10.3390/s130709029
Received: 7 May 2013 / Revised: 30 May 2013 / Accepted: 14 June 2013 / Published: 12 July 2013
Cited by 5 | PDF Full-text (785 KB) | HTML Full-text | XML Full-text
Abstract
During the last three decades; dielectrophoresis (DEP) has become a vital tool for cell manipulation and characterization due to its non-invasiveness. It is very useful in the trend towards point-of-care systems. Currently, most efforts are focused on using DEP in biomedical applications, [...] Read more.
During the last three decades; dielectrophoresis (DEP) has become a vital tool for cell manipulation and characterization due to its non-invasiveness. It is very useful in the trend towards point-of-care systems. Currently, most efforts are focused on using DEP in biomedical applications, such as the spatial manipulation of cells, the selective separation or enrichment of target cells, high-throughput molecular screening, biosensors and immunoassays. A significant amount of research on DEP has produced a wide range of microelectrode configurations. In this paper; we describe the microarray dot electrode, a promising electrode geometry to characterize and manipulate cells via DEP. The advantages offered by this type of microelectrode are also reviewed. The protocol for fabricating planar microelectrodes using photolithography is documented to demonstrate the fast and cost-effective fabrication process. Additionally; different state-of-the-art Lab-on-a-Chip (LOC) devices that have been proposed for DEP applications in the literature are reviewed. We also present our recently designed LOC device, which uses an improved microarray dot electrode configuration to address the challenges facing other devices. This type of LOC system has the capability to boost the implementation of DEP technology in practical settings such as clinical cell sorting, infection diagnosis, and enrichment of particle populations for drug development. Full article
(This article belongs to the Special Issue Ultramicroelectrode Electrochemistry - Theory and Applications)
Open AccessReview Monitoring Ion Activities In and Around Cells Using Ion-Selective Liquid-Membrane Microelectrodes
Sensors 2013, 13(1), 984-1003; doi:10.3390/s130100984
Received: 3 December 2012 / Revised: 31 December 2012 / Accepted: 2 January 2013 / Published: 15 January 2013
Cited by 3 | PDF Full-text (460 KB) | HTML Full-text | XML Full-text
Abstract
Determining the effective concentration (i.e., activity) of ions in and around living cells is important to our understanding of the contribution of those ions to cellular function. Moreover, monitoring changes in ion activities in and around cells is informative about [...] Read more.
Determining the effective concentration (i.e., activity) of ions in and around living cells is important to our understanding of the contribution of those ions to cellular function. Moreover, monitoring changes in ion activities in and around cells is informative about the actions of the transporters and/or channels operating in the cell membrane. The activity of an ion can be measured using a glass microelectrode that includes in its tip a liquid-membrane doped with an ion-selective ionophore. Because these electrodes can be fabricated with tip diameters that are less than 1 μm, they can be used to impale single cells in order to monitor the activities of intracellular ions. This review summarizes the history, theory, and practice of ion-selective microelectrode use and brings together a number of classic and recent examples of their usefulness in the realm of physiological study. Full article
(This article belongs to the Special Issue Ultramicroelectrode Electrochemistry - Theory and Applications)

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