Separation High Voltage Field Driven On-Chip Amperometric Detection in Capillary Electrophoresis

Klett, Oliver; Nyholm, Leif

doi:10.1021/ac020660h

Cited by 56 publications

(65 citation statements)

References 35 publications

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“…BPEs can be particularly useful for detecting electroactive analytes in microfluidic environments, where high electric fields and solution resistances can lead to difficulties controlling the potential of a working electrode configured in a standard three-electrode cell arrangement. 16 For example, Nyholm and coworkers have used BPEs to detect electroactive molecules in a capillary 17 and in an on-chip microfluidic device 18 by taking advantage of the electric field used for electrophoresis to induce bipolar behavior between two Au microbands that were connected externally through an ammeter (Scheme 3a). This kind of split electrode design makes it possible to directly measure the current passing through the BPE, but at the cost of complicating the system with an external electrical connection.…”

Section: Applications Of Bipolar Electrodesmentioning

confidence: 99%

Bipolar Electrodes: A Useful Tool for Concentration, Separation, and Detection of Analytes in Microelectrochemical Systems

et al. 2010

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Over the past decade, bipolar electrochemistry has emerged from relative obscurity to provide a promising new means for integrating electrochemistry into lab-ona-chip systems. This article describes the fundamental operating principles of bipolar electrodes, as well as several interesting applications.A bipolar electrode (BPE) is an electronic conductor in contact with an ionically conductive phase. When a sufficiently high electric field is applied across the ionic phase, faradaic reactions occur at the ends of the BPE even though there is no direct electrical connection between it and an external power supply. In this article, we describe the fundamental principles and some electroanalytical applications of BPEs for array-based sensing, separations, and concentration enrichment in microelectrochemical systems. Specifically, we show how the latter three operations, which are normally thought of as arising from different phenomena, are linked by processes occurring on and near BPEs confined within a convenient, miniaturized microfluidic format. The results presented here demonstrate that under a particular set of conditions, up to 1000 well-defined BPEs can be simultaneously activated and interrogated using just a single pair of driving electrodes. Furthermore, a slight change to the resistance of the buffer solution within the microfluidic channel leads to the separation and concentration enrichment of charged analytes. OVERVIEW OF BIPOLAR ELECTROCHEMISTRYA traditional three-electrode electrochemical cell, which consists of a working electrode, an auxiliary electrode, and a reference electrode, is illustrated in Scheme 1a. In this configuration, the potential of the working electrode, which is related to the energy of the electrons in the electrode, is controlled (versus a reference electrode) using a potentiostat. The potential of the solution is not directly controlled; in other words, it is at a floating potential that (in the absence of an externally applied electric field) depends on the composition of the solution. When the potential of the working electrode is set to a value more negative than that of an electroactive molecule in the solution, electrons may (depending upon kinetics) transfer from the electrode to reduce species in solution (Scheme 1b; note that positive potentials are up in this diagram to make it consistent with Scheme 1c). Similarly, oxidation reactions occur when the electron transfer is in the opposite direction. The faradaic current measured in the circuit connecting the working and auxiliary electrodes is a direct FRANÇ OIS MAVRÉ

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Section: Applications Of Bipolar Electrodesmentioning

confidence: 99%

Bipolar Electrodes: A Useful Tool for Concentration, Separation, and Detection of Analytes in Microelectrochemical Systems

et al. 2010

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“…Several examples of sensors using BPEs microfabricated on glass substrates have also been reported in the literature. [23][24][25][26] For example, our group used ECL produced by the co-oxidation of tris(bipyridine)ruthenium(II), Ru(bpy) 3…”

Section: -20mentioning

confidence: 99%

Paper-Based Bipolar Electrochemistry

Renault¹,

Scida²,

Knust³

et al. 2013

Journal of Electrochemical Science and Technology

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:We demonstrate that carbon electrodes screen-printed directly on cellulose paper can be employed to perform bipolar electrochemistry. In addition, an array of 18 screen-printed bipolar electrodes (BPEs) can be simultaneously controlled using a single pair of driving electrodes. The electrochemical state of the BPEs is read-out using electrogenerated chemiluminescence. These results are important because they demonstrate the feasibility of coupling bipolar electrochemistry to microfluidic paperbased analytical devices (µPADs) to perform highly multiplexed, low-cost measurements.

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“…The coupling effects between separation electric field and the detection electrode are also reported by other research groups. [22][23][24][25] It is worth mentioning that the observed change in tip current is mainly controlled by the electron-transfer rate where the Tafel equation is applicable. First, for solution with constant concentration, solution resistance is known only related to its shape, no matter whether an external electric field exists.…”

Section: Secm Imaging Of the Channel Opening Using Couplingimaging Modementioning

confidence: 99%

Electric‐Field Distribution at the End of a Charged Capillary—A Coupling Imaging Study

Wang¹,

Jia²,

Xia³

2008

ChemPhysChem

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The electric-field distribution at the end of a charged capillary system is detected using a scanning electrochemical microscopy (SECM) coupling imaging mode. A theoretical model based on the resistance of solution at the capillary end describes the three-dimensional distribution of the electric field. The effect of the detection electrode position and separation high voltage on solution potential is observed and analyzed. Results demonstrate that the electric field at the end-channel shows an isopotential contour changing from a disk shape into a hemispherical shape when leaving the capillary opening. The solution potential decreases along the central axis of the capillary to the detection reservoir. In the same scanning plane, the solution potential decreases along the radial direction. Increase of the separation high voltage results in the increase of the absolute solution potential but does not change the relative spatial electric-field distribution.

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Separation High Voltage Field Driven On-Chip Amperometric Detection in Capillary Electrophoresis

Cited by 56 publications

References 35 publications

Bipolar Electrodes: A Useful Tool for Concentration, Separation, and Detection of Analytes in Microelectrochemical Systems

Bipolar Electrodes: A Useful Tool for Concentration, Separation, and Detection of Analytes in Microelectrochemical Systems

Paper-Based Bipolar Electrochemistry

Electric‐Field Distribution at the End of a Charged Capillary—A Coupling Imaging Study

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